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1. 496s 22 24 22 154 am como ame sss o z ee nee sn oso S e AA AA 22 17 me e sem eno mee oo oo y on ce ev v E 222 05 e ee J gt eos a gt oom 224 21 95 T T T T T D 1 0 100 200 300 400 500 600 700 Time s Figure 12 Plot of oxygen concentration vs time for box 11 dimensions V 0 0734m A 0 0177m L 0 017m and N 3 which gives T N A T1 T2 Oxygen Concentration N m d 150 Time s Figure 13 Plot of oxygen concentration vs time for box 12 dimensions V 0 0734m A 0 0177m L 0 017m and N 7 which gives T 128s 13 21 74 Ti T2 Oxygen Concentration 96 21 2 21 1 0 250 TOT 50 100 150 20 Time s Figure 14 Plot of oxygen concentration vs time for box 14 dimensions V 0 0734m A 0 0177m L 0 15m and N 7 which gives T 230s 6 Discussion 6 1 Field Suitability 6 1 1 Weatherproofing Keeping the electronics safe against the elements ap pears to have been a success in lab tests The tech nique of preserving wood with epoxy makes a signif icant difference to the rate at which it deteriorates and the general waterproofing of the whole control box was achieved too The first dunk test suggested there was still a little work to do but after improve ments to the door seals the small amount of leakage in the second dunk test
2. Following the trend from previous work an open system respirometry chamber was developed which aims to mimic the nesting box used by Grey Mouse Lemurs at BZG The instrument comprises of two boxes the first of which houses all circuitry a data storage device and an Amicus18 board with an in build PIC microcontroller which is programmed to manage the functions of the instrument Connected to this is the lemur nesting box On both the inside and the outside of the nesting box is an EC410 elec trochemical oxygen sensor The sensors are used in combination to measure the oxygen consumption of animals within the box Cohen and Humphries experienced several issues throughout building the instrument and testing it at BZG which ultimately resulted in a lack of data throughout the two days of testing the lemurs only entered the nesting box for short periods of time af ter being encouraged by placing food within the box Most likely the lemurs never became familiar or com fortable enough with the device owing to the lack of time for which it was inside their enclosure More over the nesting box built by Cohen and Humphries is a poorly considered replica of those which are used by lemurs at the zoo this may have been a factor in lemurs reluctance to use the box Cohen and Humphries were unable to implement a portable storage device due to difficulties in pro graming the Ammicusl8 board The solution was to use an LCD screen conne
3. The card should read Setup each time the device is powered on Ifthe data reads Setup multiple times or more times than the device has been powered on and off without the data being deleted from the micro SD card then there may be a faulty connection in the power circuit which is causing the device to be powered down e Check all connections in the power circuit are strongly connected and able to carry current e Check that the black power connector is fully inserted into the main Arduino board 11 User Guide UoB GIP 2012 13 4 1 Error 1 Animal Counter Error Error one is an animal counter error It occurs when there is a faulty line of sight between a sensor and LED or a faulty electrical connection on either of these The error presents itself in the data as Error 1 Animal counter error when the device prints its final data When the error occurs the animal count is reset to 0 e Check the line of sight of the LED and sensor on the entrance to the nest box e Check all connections are complete e Check senor voltage levels both next to and away from the LED e Replace any faulty parts 4 2 Error 2 Negative Animal Count Error two is a negative count error It occurs when the system identifies a negative number of animals in the box It is common for this error to present itself after error 1 as the animal count is reset whilst animals are still in the box This error also resets the animal count allowing it to
4. a necessity should it be taken to the tropical climes Madagascar Finally the whole box was painted black to match that of the zoo 3 1 2 Instrumentation Box As with the nest box the box containing the elec tronics was also constructed of WBP plywood It was designed to have the capacity to fit all the es sential electronics plus a power supply the size was made as compact as possible to ensure portability The interior was then to have wooden dividers to keep components separate and prevent damage from excessive movement of parts within the box Much of the design of the instrument box centred on it being made waterproof for use in the field which is discussed in section 3 1 9 3 1 3 The Arduino The project aims lend themselves to a small cheap microcontroller unit that can take inputs from several different sensors perform calculations and logic and is able to store data After research it appeared that the product that best fitted these characteristics was an Arduino UNO which has 20 I O pins digital and analogue costs under 20 and has a wide variety of attachments that can be used for various functions including data storage The microcontroller chip on the Arduino UNO is an ATmega328 which has a flash memory of 32kb and with its 20MHz operating frequency can achieve nearly 20MIPS million instructions per second 119 32kb of memory was deemed to be appropriate to contain all of the project code assuming it
5. double BMR BMRsum BMRnow BMRday D avtemp double Percentage Temp double percentin percentout tempin tempout int h j k E Run char c 8 c2 6 d 8 d2 6 void setup 4 Serial begin 9600 pinMode 10 OUTPUT Serial println Initializing SD card if SD begin chipSelect t Serial println card failed or not present return Serial println card initialized dataFile SD open data txt FILE WRITE if dataFile dataFile println Setup Serial println Setup dataFile close if the file doesn t open pop up an error else Serial println error opening file txt void loop start animal detection t 0 k 0 BMRsum 0 if analogRead sensor0 600 mouse lemur in entrance lv array 0 1 else if analogRead sensor0 gt 600 no mouse lemur in entrance array 0 0 if analogRead sensorl lt 600 mouse lemur in entrance array 1 1 else if analogRead sensorl gt 600 no mouse lemur in entrance array 1 0 switch state case 1 t array 0 1 amp amp array 1 0 state 2 a if array 0 0 amp amp array 1 1 state 5 break case 2 if array 0 0 amp amp array 1 0 state 1 n if array 0 1 amp amp array 1 1 state 3 break case 3 t array 0 1 amp amp array 1 0 state 2 if array
6. 0 0 amp amp array 1 1 state 4 break case 4 E array 0 1 amp amp array 1 1 state 3 else if array 0 0 amp amp array 1 0 lemnum 1 state 1 gt break case 5 if array 0 0 amp amp array 1 0 state 1 p if array 0 1 amp amp array 1 1 state 6 break case 6 a array 0 0 amp amp array 1 1 state 5 Eo if array 0 1 amp amp array 1 0 state 7 break case 7 if array 0 1 amp amp array 1 1 state 6 oo if array 0 0 amp amp array 1 0 lemnum 1 state 1 break end animal detection numnow lemnum while lemnum initial while animal present take data t 1 Serial println t delay 1 slows the time loop slightly 1 microsecond if t 0 amp amp t966500 0 amp amp t lt 13000 ignores values taken below equilibration time Percentage Serial print O2 inside Serial print percentin Serial print t t Serial print O2 outside Serial print percentout Serial println 96 dataFile SD open data txt FILE WRITE if dataFile dataFile print percentin vi dataFile print t dataFile println percentout dataFile close if the file doesn t open pop up an error else Serial println err
7. 5 5 1 Paraffin Wax Burner Effective BMR The effective BMR of a single 10g paraffin wax burner was found to be 13 1 5 kcal day The error was cal culated using the standard error in the mean 5 5 2 Oxygen Concentrations in Varying Box Dimensions and Varying Oxygen Con sumption Figures 9 14 show examples of the plots made for cer tain box burner combinations T1 represents the time at which the animal enters the box and T2 repre sents the time at which steady state is reached The steady state waiting period T is given by T2 T1 For each box burner combination T is averaged over the 5 plots The full results are displayed in appendix VII 234 A s 22 5 t ES c 2 224 ha Ti T2 5 9 221 5 o o 21 lt Pl 20 541 T T T 1 0 50 100 150 200 Time s Figure 9 Plot of oxygen concentration vs time for box 6 dimensions V 0 00670m A 0 001963m L 0 04m and N 3 which gives T 1381s 12 T2 Oxygen Concentration N 150 200 Time s 100 250 300 Figure 10 Plot of oxygen concentration vs time for box 8 dimensions V 0 0353m3 A 0 001963m L 0 04m and N 3 which gives T 210s T2 N Oxygen Concentration N N 20 6 T 1 0 400 800 Time s 100 200 300 500 600 700 Figure 11 Plot of oxygen concentration vs time for box 9 dimensions V 0 0734m A 0 001963m L 0 017m and N 3 which gives T
8. absorptive state which means that its digestive system is not active The animal must be under no physiological or physical stress as this can significantly raise its metabolism The animal must also be in a thermoneutral zone which is defined as a temperature range at which an animal s heat pro duction is equal to heat loss to its surroundings l There are many alternative metabolic indices such as the field metabolic rate FMR which is the cost of free existence in the wild and includes other energy penalties such as locomotion thermoregula tion reproduction and tissue growth Although FMR gives a more accurate picture of real world energy consumption BMR is a widely used and important parameter as it allows for comparison across species and higher taxal4 2 2 Motivation and the Importance of BMR Animals housed in European zoos are frequently overfed which can lead to obesity and its associ ated health problems such as diabetes and coronary heart disease The problem of overfeeding is partic ularly pronounced in lemurs due to their low BMR which is often overlooked by gamekeepers Obesity in mammals can cause infertility or miscarriagel and this is a major concern in the conservation of endangered species reduced reproductive efficiency due to overfeeding would be counterproductive to the vital conservation work carried out at zoos Nutri tion plans in zoos are to a large extent based on trial and error Gameke
9. alignment should be carried out with the OSCaR in situ While the oxygen sensor can simply be slipped into the wall of the nest box the light gates and scales need to be fitted Light gate false front Oxygen sensor hole Scale wiring hole Light gate wiring hole Bolt hole Figure 1 Diagram of hole positioning on an adapted nest box which has three front panels housing the light gates the nest box is denoted by the solid box while the OSCaR Device outline is shown as dashed This shows how OSCaR can be attached to larger nest boxes than itself provided that it is aligned with the front bottom corner of the nest box User Guide UoB GIP 2012 13 2 2 1 Measurement of the new box Before fitting any hardware let s deal with the software firstly the area of the animal hole in the box and the depth of this hole must be measured The measurement of the depth of the hole shown in figure 1 can be carried out simply with a ruler The trickier measurement is that of the area of the animal hole for which the calculation changes depending on the shape for a circular hole the diameter of the opening is measured and the following equation is then applied to find the area D 2 Area m 5 Figure 1 Demonstration of what is meant by hole depth Where Dis the diameter and Tr is a constant roughly equal to 3 142 If the opening is square or rectangular then the area is simply equal to the length of the two sides multiplied to
10. are technically suitable for air travel complications can easily arise refer to appendix V for more details 3 1 9 Waterproofing In order to be used in the field the delicate electron ics had to be waterproofed to prevent failure The main challenge in this case was keeping everything sealed while still running electronics between the two separable parts of the equipment This was achieved by attaching rubber washers around any opening in the instrumentation box these would then form a good seal when the instrumentation and nest boxes were bolted tightly together The nest box oxygen sensor was also contained within a small piece of pipe protruding from the side of the instrumentation box to add further protection The design of the instrument box itself was planned so as to give minimal skywards facing joins where water may seep through To add further wa terproofing to the joins they were sealed on the inside of the box with silicone sealant This is also how the light gate LEDs and sensors were secured and waterproofed The door to the box had rubber seals attached and was fastened with compression clips to give a secure seal The wood of the instrumentation box also needed protection from the long term effects of rain such as warping delamination and boils which could af fect the structural integrity and water tightness of the container This was achieved by coating the wooden panels of the box with epoxy resin g
11. in kcal day and prints all the relevant data to the storage device If the animal is the last to leave the scales zero value intercept is re calibrated to take into account any nesting material added to the nest box and the device is returned to its original more inactive state A copy of the annotated code can be found in appendix II 3 3 Calculating BMR 3 3 1 Fick s Law Fick s first law is as followsl2 l Oc where J is the flux in units of mol m s D is the diffusion coefficient in units of m s and is the concentration gradient in units of mol m This equation describes the steady state flow of a sub stance in one dimension Steady state implies that for any quantity of the system in question the partial derivative with respect to time is zero If it assumed that the flow of oxygen associated with a lemur inside the calorimetry chamber has reached steady state i e the concentration at any point from just outside to well within the nesting box is unchanging in time then equation 5 can be used to estimate the flow of oxygen into the nesting box By assuming that the oxygen concentration varies linearly across the entrance to the nesting box 2 is given by the formula 2 xc 6 a Where C and Ca are the oxygen concentrations in moles m outside and inside of the nesting box respectively and X is the length of the nesting box entrance in metres 3 3 2 Diffusion Coefficient Experimental data s
12. mySerialout begin 9600 mySerialout write T r n delay 7 while mySerialout available gt 0 d j mySerialout read j 1 e2 0 e 2 a2 0 4 2 e2 1 e 3 a2 1 a 3 e2 2 e 4 a2 2 a 4 e2 3 e 5 a2 3 d 5 e2 4 e 6 a2 4 q 6 e2 5 e 7 d2 5 4 7 tempin atof c2 tempout atof d2 return tempin tempout int massFinder double offset int mass 0 double loadCellValueAverage 0 loadCellValueAverage analogRead A2 for int count 0 count lt 200 count int loadCellValue analogRead A2 loadCellValueAverage 0 95 loadCellValueAverage 0 05x loadCellValue delay 1 const double gradient 0 7852 double intercept 24 513 offset adds the offset to the intercept to account for any nesting material or similar mass loadCellValueAveragex gradient intercept if mass lt 10 simple clause to set any very low measured masses to zero this line won t usually be used in normal function as mass is only taken when lemurs mass gt 10g are in the box mass 0 return mass xii Appendix III Financial Report Group industrial projects are allocated 100 budget per person making a total budget of 400 The bud get is generally used for travel expenses but in this case the industrial partner was based in Bristol and the project itself needed to purchase many items not found in the lab therefore the budget was lent less to tr
13. one or two millimetres smaller in each dimension 2 Unscrew the previous platform from the load cell and screw in the one that was cut in the previous step The load cell should be approximately centred on the platform and the wooden spacer between the platform and the cell should be used this allows the load cell to flex freely which is how weight is measured 3 Atthe opposite end of the load cell to where the platform was attached there are two more holes which will be used to attach the scales to the box Measure where these two holes lie in relation to the base of the nest box and then drill appropriately sized holes in the base at these points 4 Now secure the full apparatus into the nest box with the screws provided ensuring you run the wires from the load cell though the appropriate hole 5 As with the light gates the scales must be calibrated with the Arduino this also requires the use of a spreadsheet program such as Microsoft Excel Due to the ubiquity of Excel all instructions referring to spreadsheets will use Excel commands but most other spreadsheet programs are very similar Calibration is as follows a First plug the Arduino into a computer using a USB cable b Inside the OSCaR control box there is a circuit board with several screw pin terminals soldered on to it Connect the terminal marked V to the 5V pin of the Arduino and the terminal marked V to the ground GND pin User Guide UoB GIP 2012 13
14. oxygen sensors Fergus Kidd proposed discussion of previously used methods for calibration of oxygen sensors as used by Guy Cohen in the 2011 project report of measuring the BMR of the Grey mouse lemur Action Prof Hoerber suggested contact with Prof Rob Richardson and Dr Adrian Barnes as their equipment was used 3 Next Meeting Action Sarah Buxton arrange meetings with Prof Rob Richardson and Dr Adrian Barnes if necessary after initial contact El e Ke University of ES BRISTOL School of Physics Bristol Zoo Gardens Group Industrial Project Meeting Interim Presentation Date 22 02 2013 Location H H Wills Physics Laboratory Chairperson Nicholas Pestell Secretary Fergus Kidd In Attendance Professor Ashraf Alam Professor of Physics and Project Assessor Dr Christoph Schwitzer Head of Research BZG Sarah Buxton Communications Officer Apologies N A 1 Presentation The group gave the interim presentation of progress made on the project to date to Prof Alam and Dr Schwitzer The relevance of work to the given brief was shown and practical demonstrations of working light gate detection oxygen and temperature sensing as well as the load cell for mass measurement were given Detailed box designs were also shown as well as a timetable for the future work This document addresses two specific issues that require relevant action that arose in the question section at the end of the presentation 2 Availability of Pow
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16. the Arduino to directly resolve Consequently the sig nal needed to be amplified by a custom circuit this consisted of an INA125P amplifier through which the output voltage of the Wheatstone bridge was run The amplifying circuit which is shown in the full circuit diagram in appendix I then outputted a single voltage to Arduino with reference to ground The gain of the amplifier could be adjusted depend ing on the gain resistance applied across it a 100 resistor was added in this case giving a gain of ap proximately 6000 and amplifying the voltage into the range of volts This output then needed to be calibrated to cor respond to a mass placed on the scales which is explained in section 3 4 1 3 1 8 Power Source The Arduino computer requires a power source of be tween 6V and 15V which it then regulates down to 5V to run its own systems and also power any at tached sensors Initially this was provided by two 9V PP9 batteries which have a high energy density 5000mAh each but are only single use making pow ering the device for long periods of time expensive This meant that the majority of experimentation was carried out using 6V lead acid batteries which have a slightly lower energy density but are easily recharge able the major disadvantage of these batteries was that a capacity of only 4000mAh could fit into the battery compartment of OSCaR which was designed with PP9s in mind Also while lead acid batteries
17. the reader Later sections will cover e Setting up the equipment to take readings e Retrieving and interpreting data e Adaptation of the OSCaR to new nest boxes e Common issues and their resolution 1 1 Background OSCaR effectively turns an animal s nest box into an open system respirometry chamber It works by measuring the oxygen concentrations inside and outside a nest box while an animal is present which allows the oxygen consumed to be calculated Due to an approximately constant amount of oxygen consumed per unit energy knowing oxygen consumed allows for BMR to be calculated OSCaR leaves no fiddling around with complex data sets or further calculation it simply gives the animal s BMR no fuss The device also incorporates light gates in the nest box entrance that act as advanced presence detectors These allow not only the presence of an animal in a nest box to be discerned but also the number of animals in the box at any one time a real advantage when animals nest in pairs or groups Furthermore a scale is also incorporated seamlessly into the base of the nesting box allowing masses of single or multiple nesting animals to be measured this can be important for telling animals in a population apart and also for trying to ascertain allometric scaling laws for the BMR of a species Advanced logic allows animals to bring food or nesting material into their nest without this affecting any weight measurements Naturally along with
18. 0 017 0 017 0 04 0 04 0 017 0 04 0 017 0 0005 0 0005 0 0005 0 0005 0 0005 0 0005 0 0005 N I 2 jl 2 3 3 3 T s 162 12 197 17 226 20 252 10 109 9 121 5 221 20 Box 8 Box 13 Box 14 Vim 0 0353 0 0734 0 0734 0 0734 0 0734 0 0734 0 0734 0 0002 0 0002 0 0002 0 0002 0 0002 0 0002 0 0002 A m 0 001963 0 001963 0 001963 0 0177 0 0177 0 0177 0 0177 0 00008 0 00008 0 00008 0 0002 0 0002 0 0002 0 0002 L m 0 04 0 017 0 04 0 017 0 017 0 15 0 15 0 0005 0 0005 0 0005 0 0005 0 0005 0 0005 0 0005 N 3 3 J T s 228 22 555 47 601 43 N A 127 30 248 51 261 23 XV Appendix VIII Zoo Survey Responses Below is the full set of responses to market surveys HOM Jno ejyeioeudde Ajjeay 101 u09 0 pue yoeye oj see sBulul Jejus Buiney jo Buryuiyy no envy 1e 090 pei ay o payoeye SEM soap ay sinwel 10 siosuas AyAoe pesn aney sisAjeue jijeueq 1s095 Jepeoug e ye yool pue panove s yeueq Aue euiuuejep ueuj pue snoo euy I A e YIM pue joeloud e jo 1xejuoo y ulyym sdeylad Aysepow ues 0 1s q eq pinom y s unnou jewiue pue s3soo uejes pare yum yes ey o uondnusip ey snid suoneJepisuoo eoyoeld pue ajejjam aie eJeu L Buljeos oujewojje jo jxajuoo ayy uium penopued jnyesn eq pinos y exi Spu os SIT elis S 5X5ep sinuie esoobuow Byelis paumoJo sinuje pejie1 8urJ 8J6J 8M euue uo joeduui esjeApe ou pinom eeu eunsue oj eey pinom em
19. 0 01ml s suggests the con trol box is well sealed It is also worth noting that these tests subjected the equipment to conditions far more severe than would be expected in the field un der normal precipitation it is very unlikely that any leakage at all would occur 6 1 2 Power Supply The longest lasting power supply available was a pair of 9V PP9s which could power the system for around 33 hours this was good but fell far short of the 72 hour lifetime that was hoped for This was for a vari ety of reasons the first being the power consumption of the Ethernet shield which can be seen in appendix Vl as being more than all of the other components combined There are alternatives available though at the time of purchasing the Arduino and Ethernet shield there was a relative ignorance of the device s capabilities and the abundance of additional com ponents this meant the decision to purchase the Ethernet shield was rushed as it was an Arduino pro duced add on with the necessary functions Were it known that there were other shields avail able from third party manufacturers that were solely SD card interfaces without the energy wasting Eth ernet chip one of these would have been chosen furthermore just after purchase Arduino released a new version of their wireless shield with an SD interface this too would have been perfect as this particular shield did not come with a wireless chip and antenna as standard it
20. 0002 eee 3 3 Experimental Design 4 orl Device Design 5 uocem mom de a ecb REUS lee ee RRA W SC tas 9 4 Soba Nesting Box ses oni LiT Fen 0X se eee ak Bawa eee SOR Se ee ae EAT 4 3 1 2 Instrumentation Box 22 eoo Dx eoe eos a X Ee 4 31133 The Arduino atm Et 622 E nite AA ES kaa 4 3 14 Data Storage tery e e a de eee ee A AA e etus 5 3 15 57 OXY PCM Sensors i 5 dd bee Ma d k donet eee es 5 3 1 6 Light Gates ted in 9C dae de e eor c se TE enda 5 S lA cales lil ee el wow S L me The ta Bale s es 6 3 1 8 Power SOUrCE gt a 424 4444 od cial ale Ble eG RR aa 6 3 1 9 WaterprooHBg 445860 8 ne hoe bbe ee been wwe S e S Y WE ate 6 3 110 Animal Proonng i2 EE See eee oo Ea ad ee y y Ta 7 312 GOTE aS Gove E S 5 LOREM aie ve GGA A Bot 7 3 3 Calculating BMR 6 5 24 5 5 esu wo av arate sb fe Go ate N q edem ebur ee le ae 7 dsl Fick s Laws nudos us RII eerie ee EE EEO es 7 3 9 2 Diffusion Coefficient og dod ERE Rd iugi ea Bh abe fa T 3 3 3 Derivation of Final Equation rs 7 3 4 Calibration and Design Testing e e 8 3 41 Scale Calibration mn a t oe oen an Bk beke al e Wu e ee UQ 8 34 2 Testing Waterproofing te dd wile eee E xd a aa Veg 9 343 Power Source Testing 4 nn ane ana serene o s a Ad a Ee a oe 9 4 Experimental Method 9 4 1 Testing with a Domestic Hamster 2 0 00000000 000000004 9 4 2 Bristol Zoological Gardens eee 10 4 37 Size Limitations x deer see
21. 7 K Schmidt Neilson Animal Physiology Adaptation and Environment Cambridge University Press 1997 P J Moors A Closed circuit respirometer for measuring the average daily metabolic rate of small animals Copenhagen Oikos 28 304 308 1977 G Cohen An investigation into the basal metabolic rates of Grey mouse lemurs through non invasive automatic measurement of Oxygen concentrations Bristol Department of Physics University of Bristol 2011 J Humphreys 2011 A Portable Device for Measurement of Basal Rate of Metabolism University of Bristol Arduino Arduino Uno Online Available http arduino cc en Main ArduinoBoardUno accessed 01 05 2013 SST Sensing LuminOx Preliminary Datasheet SST Sensing Ltd 2011 xlii 21 22 23 24 25 26 P L K P G H S L amp J C R Optical fiber fluorescence sensor system for measuring oxygen levels in gas involves the use of a fiber optic fluorescence oxygen sensor containing a ruthenium complex for quenching the fluorescence by singlet oxygen atoms United States patent application 2001 H Tyrrell The Origin and Present Status of Fick s Diffusion Law Journal of Chemical Education 41 397 400 1964 M Denny Air and Water The Biology And Physics of Life s Media Precenton University Press 1993 B Roebuck M Brooks amp M G Gee Load cell ringing in high rate compression tests Advances in Experimental Mechan
22. SCHOOL OF PHYSICS Ec University of DE BRISTOL FINAL YEAR PROJECT REPORT NAMES Sarah Buxton Charles Hannigan Fergus Kidd Nicholas Pestell COURSE Physics BSc TITLE Non intrusive Measurement of Basal Metabolic Rate using an Open System Calorimetry Respirometer OSCaR YEAR OF SUBMISSION 2013 SUPERVISOR Professor Peter Barham NUMBER OF WORDS 10054 School of Physics Tyndall Avenue Bristol BS8 1TL 2012 13 Declaration and Acknowledgements Most of the work for this project was conducted independently by the group with little outside help within our group we split work up fairly and in a manner that played towards individual strengths This report is a continuation of our literature reviews of November 2012 with much of our prior research being revisited Notable exceptions to this were Tom Kennedy in the lab who was very helpful in sourcing a lot of project materials and was always available to discuss the merits of particular methods Richard Exley and Adrian Crimp in the UoB Physics Mechanical Workshop very kindly made the plywood cuts for our box and Sam Wright a fellow 3rd year physicist who generously took our instrument home with him to use with his hamster Mitchell Finally there s all the staff at Bristol zoo who helped us along the way specifically Dr Christoph Schwitzer for his guidance on lemur habits and previous projects Dr Sue Dow for administrative issues and Sarah H
23. These advantages were in addi tion to the LuminOx sensor s digital communication abilities and pre calibration by the manufacturer Additionally the sensor has the ability to measure atmospheric pressure and temperature which is an advantage to calculate the diffusion constant of air were to maximum precision LuminOx works on a completely different princi ple to most other oxygen sensors being based on the principle of fluorescence quenching by oxygen While the exact technology behind the sensor is proprietary a high level view of the process is as follows 1 An LED is pulsed into a fluorescent material which excites it 2 The excited matrix fluoresces at a different wavelength to the LED with the intensity of fluorescence detected with an optical sensor 3 If instead of returning to a non excited state by emitting a photon an excited molecule en counters an oxygen molecule its energy can be transferred non radiatively to the oxygen thus preventing quenching fluorescence 4 The amount the material fluoresces is inversely proportional to the probability of an excited molecule encountering an O2 molecule This is directly proportional to the concentration of oxygen in the fluorescent complex which is it self directly proportional to and in dynamic equilibrium with the concentration of oxygen in the atmosphere Two LuminOx sensors were used in OSCaR one was fed from the instrument box into the nest box t
24. all and Simon Robinson from the keepers team who met us every day so we could collect data and change batteries Abstract The aim of this project was to obtain a non intrusive and indirect measurement of the basal metabolic rate of the Grey mouse lemur Microcebus murinus using a custom built open system calorimetry respirometer No value of basal metabolic rate for a lemur was obtained however investigation with a Djungarian hamster Phodopus sungorus yielded a basal metabolic rate of 22 4 2 8 kcal day This is close to the expected energy expenditure of this species and is evidence that the calorimetry respirometer produced is a viable method of measuring metabolic rate The research was undertaken with a view to applying the calorimetry respirometer to other species of mammals and birds The theoretical size limitations of the device were considered and several other species identified as potential candidates for investigation il Table of Contents 1 Introduction 1 2 Detailed Background 1 2 1 Basal Metabolic Rate 5 sa oen oef st ts O dd a EGRE 1 2 2 Motivation and the Importance of BMR e 1 2a HISTOL aaan ke arn rn Gen op a A A Ra ce AG eh e e Der es Acs 2 2 4 Methods of Measurement 2 2 41 Direct Calorimetry a iei cs an en ee es ee UU o pod eue ae 2 2402 Indirect Calorimetry wanten ot nt ee ee Aide dele ee kh de ho Gla UE ta 2 2 5 Previous Work at the University of Bristol 0 000000
25. amp array 1 0 state 2 Eo if array 0 0 amp amp array 1 1 state 5 break case 2 if array 0 0 amp amp array 1 0 state 1 j n if array 0 1 amp amp array 1 1 state 3 j break case 3 array 0 1 amp amp array 1 0 state 2 j Am if array 0 0 amp amp array 1 1 state 4 j break case 4 if array 0 1 amp amp array 1 1 state 3 j an if array 0 0 amp amp array 1 0 lemnum 1 state 1 break viii case 5 i array 0 0 amp amp array 1 0 state 1 dll if array 0 1 amp amp array 1 1 state 6 j break case 6 if array 0 0 amp amp array 1 1 state 5 j if array 0 1 amp amp array 1 0 state 7 break case 7 j array 0 1 amp amp array 1 1 state 6 if array 0 0 amp amp array 1 0 lemnum 1 state 1 j break end animal detection monitoring in this loop if lemnum 0 initial lemnum Serial println lemnumchange dataFile SD open data txt FILE WRITE if dataFile dataFile print lemnum change t dataFile println lemnum dataFile close if the file doesn t open pop up an error else Serial println error opening fi
26. an Publishing Co pp 55 47 48 51 53 I D Hume Marsupial Metabolics Cambridge University Press pp 2 17 1999 S Goodchild and C Schwitzer The Problems of Obesity in Captive Lemurs International Zoo News Vol 55 No 6 pp 353 357 2008 E Knobil and J D Neill Physiology of Reproduction Gulf Professional Publishing Ch 47 pp 2555 2563 2006 S Wolfensohn and M Lloyd Handbook of Laboratory Animal Management and Welfare John Wiley amp Sons Chapter 15 pp 330 333 2012 S C Rastogi Essentials of Animal Physiology New Age International p122 1977 C R White and R S Seymour Allometric Scaling of Mammalian Metabolism Journal of Experi mental Biology 208 1611 1619 2005 M Kleiber Body Size and Metabolic Rate Physiological Reviews 27 511 541 1932 F Bokma Evidence Against Universal Metabolic Allometry Functional Ecology Volume 18 Issue 2 pages 184 187 2004 J R Speakman R M McDevitt and K R Cole Measurement of Basal Metabolic Rates Don t Lose Sight of Reality in the Quest for Comparability Physiological Zoology Vol 66 No 6 pp 1045 1049 2003 R C Hill Challenges in Measuring Energy Expenditure in Companion Animals A Clinicians Perspec tive The Journal of Nutrition 2006 D Randell W Burggren amp K French Animal Physiology Mechanics and Adaptions fourth edition W H Freeman and Company p 674 199
27. avel and more to procurement with a small amount spent on refreshments for meetings and presentations A full income expenditure table is shown on the following page with the total expenditure being 274 59 This includes purchases of multipack items often where only a fraction of the pack was used and also of items that were later found not to be needed for the project For those reasons total expenditure is not a true reflection of the cost of building one OSCaR instead simply taking the cost of necessary parts not including tools and power source which is subject to user choice the cost of one instrument comes to 144 35 A full list of equipment is given in Appendix XI along with their supplier of origin INCOME Item Price per Unit Number of Units Total GIP Initia Budget 400 00 Total income 400 00 EXPENDITURE Item Price per Unit Number of Units Total Equipment Costs Arduino Uno 18 04 1 18 04 Arduino Ethernet Shield 25 42 1 25 42 Infrared T 1 LED 880nm 0 91 4 3 64 Luminox Oxygen Sensor 28 44 3 85 32 Salter Black Kitchen Scales 9 99 1 9 99 Instrumentation amplifier INA125P 4 39 2 4 39 Structural Hardwood Plywood WBP 28 28 1 28 28 Epoxy Coating Resin 500g Pack 2p gram 500g 10 00 Eveready PP9 Zinc Carbon 9V battery 3 90 7 27 30 Wilkinson Paint Brushes Spk 2 00 4 2 00 Wilkinson Paint Container 1 00 1 1 00 Sainsbury s Basics Vineger 0 22 i 0 22 Brass Plated Hinges 3 97 1 3 97 Spr
28. ay Paint Matt Black 5 18 1 5 18 Copper Tube Crimp Lugs 6mm 1 98 1 98 PVC coupler 20mm Black 0 11 2 0 22 PEX Insert 22mm 0 17 2 0 34 Weatherstrip P profile brown 6 48 1 6 48 UltraFire 18650 Rechargeable Battery 2 30 4 9 20 Battery Holder for 18650 Battery 1 00 2 2 00 DC power cable mount plug 2 1mm 0 50 10 495 PCB mount DC power socket 2 1mm 0 55 10 5 49 Press studs for PP9 cell pair 0 91 5 457 SD5620 OptoSchmitt Detector 3 32 2 6 64 Spring loaded mini steel toggle latch 2 99 2 5 98 Wilko Everyday Value Lantern Battery 6V 1 99 3 1 99 Total Equipment Costs 274 59 Incidental Costs Terry s Milk Chocolate Orange 2 75 275 Sainsbury s Biscuit Variety Pack 1 00 1 1 00 Sainsbury s Semi Skimmed Milk 1 pint 0 49 2 0 98 Total Incidental Costs 4 73 Total Expenditure 279 32 Budget Remaining 120 68 xiii A list of components used to build the instrument Appendix IV Parts List with Suppliers Price per Unit 18 04 Supplier RS Components Arduino Ethernet Shield 25 42 RS Components Infrared T 1 LED 880nm 0 91 RS Components Luminox Oxygen Sensor 28 44 SST Sensing Salter Black Kitchen Scales 9 99 Tesco com Instrumentation amplifier INA125P 4 39 RS Components Structural Hardwood Plywood WBP 28 28 Travis Perkins 2p gram EasyComposites com 3 90 RS Components Wilkinson 0 40 To
29. c Power the load cell this means connecting the red wire of the load cell to the E screw pin on the circuit board and the black wire to the E screw pin d Connect the signal wires attach the white wire from the load cell to the screw pin marked S and the green wire to the pin S Then connect the analog 2 pin on the Arduino to the screw pin on the board marked Signal e Now open the Arduino software and paste in the following code void setup Serial begin 9600 void loop int loadCellValue analogRead A2 float massVoltage loadCellValue Serial printin massVoltage f Upload the code to the Arduino and then open the serial monitor Ctrl Shift M g Calibrating the scale involves adding known masses to the scale and comparing with what the Arduino reads this means having a set of masses or more likely a pre calibrated set of scales e g kitchen scales that can be used to measure an object before it is placed in the nest box scale If no masses are on hand a great way to create a mass is with a lightweight vessel filled with varying amounts of water h With no weight on the scales the serial monitor should read relatively low values but is unlikely to be zero You should add a range of masses from 0 to around 500g on your scales and note down said mass and the corresponding serial monitor value in adjacent columns in the spreadsheet Around 10 data points should suffice i Now collate this
30. cause battery capacity is measured in milliamp hours mAh and the current drawn is on the order of milliamps therefore Battery Capacity Battery Life 12 Current Drawn This knowledge was important for knowing how often battery packs needed changing in order to max imise data collection time 4 Experimental Method 4 1 Testing with a Domestic Hamster To test the system with a live subject a domesti cated Djungarian hamster Phodopus sungorus was used The reason for using a domesticated hamster is that they are handleable and much faster to ac cept changes to their smaller enclosures while being of a similar size to a mouse lemur The device was placed into the hamsters cage with all other distrac tions and sleeping compartments were removed The OSCaR was then powered on and left for a period of 48 hours taking readings every ten seconds after detection of animal entry The hamster was then left to freely enter and exit the device at will so that the animal was not under stress when measurements were taken 4 2 Bristol Zoological Gardens The OSCaR was left in the Lemur enclosure in Twi light world at BZG for 4 weeks as a stand alone sys tem where batteries were changed and data collected every 48 hours when PP9 batteries were used and ev ery 24 hours when the rechargeable lead acid batteries were used 4 3 Size Limitations The technique conceived through this on going project has the potential t
31. correct itself when all remaining animals have left The error presents itself in the data as Error 2 Negative Animal Count when the device prints its final data e Discard Data with this Error 4 3 Error 3 and Error 4 Oxygen sensor not working Errors 3 and 4 alert the user that one or both of the oxygen sensors are not functioning correctly The error presents itself amongst the data as Error 3 Inside Oxygen sensor not working and Error 4 Outside Oxygen sensor not working The error may occasionally present itself at random in the data which should be ignored The error is only valid if presented multiple times in a row e Check connections to relevant sensor e If problems continue replace relevant sensor 12 User Guide UoB GIP 2012 13 5 Appendices The User Manual does contain appendices but they are duplicates ofthose already found within the project report appendices 13 Appendix X Meeting Minutes The following pages contain minutes from group meetings which were compiled by the group secretary Fergus Kidd as part of the Industrial Project XXXIV El e Ke University of ES BRISTOL School of Physics Bristol Zoo Gardens Group Industrial Project Meeting Initial Meeting Date 6 11 2012 Location H H Wills Physics Laboratory Chairperson Nicholas Pestell Secretary Fergus Kidd In Attendance Professor Peter Barham Project Supervisor Charles Hannigan Treasurer Sarah Buxton Communications Off
32. cted to the instrument which outputted oxygen concentrations This method required constant observation thus rendering the in strument impractical for use in the field something which Cohen expressed strongly in his report Col lecting data was extremely hard this is because it is difficult to maintain focus on a screen so small for hours HI A single light gate system was implemented to de termine if the nesting box was occupied Readings were taken for one hour after the light gate was trig gered This technique neglects to consider whether a lemur is entering or leaving the box meaning data collection opportunities are lost or conversely data is collected needlesslyll 3 Experimental Design 3 1 Device Design The instrument was designed with the project aims in mind the overarching themes being those of durabil ity portability accuracy and animal comfort welfare Within each of these areas simplicity and cost effi cacy were also considered in order to be able to make the device easy and cheap to reproduce or fix The basic idea for the design which differs from previous works was to have the box containing the electronics and instrumentation attached but com pletely separable from the nesting box this was achieved by tightly bolting the two parts together This would allow the instrument to be removed and then attached to another nest box so that a different species can be researched Furthermore for re
33. d suejd UORLJNN Ayseqo Buionper sueid uonumnN sensojoue ey UI SEA enoge eu 10 jog seA seinsojoue ayy UI seA spaau uo juepuadag uawou ay 3e 0013 01 dn 0013 uey ssal Jepee ooz u amp inquip3 wee jewjuy yoJessey Y uonenesuog Jo peen Kaesonpy pue uoueesey uonenIssuog 40 1O1981Iq ooz SS6J5AWL Wed e16ojooz joo ied ooz j Bieg seybnH euio jems yez 1009 wepy UEWMOId kwy xvii Appendix IX User Manual The following pages contain a user manual written to accompany the OSCaR which helps to fulfil one of the initital aims of having an easy to use metabolic chamber xviii El University of BRISTOL Open System Calorimetry Respirometer OSCaR User Guide Version 1 3 Hello We understand that electronic instrumentation can be intimidating at times especially when there is no documentation to accompany it This is why we have created this guide to accompany the instrumentation box for measuring the BMR of animals including information on adapting the equipment for different animals and building duplicate apparatus from scratch as well as the more basic day to day functions We hope that this guide helps you with any enquiries you may have regarding the equipment and therefore furthers any health or conservation goals you may have regarding the observed animal Sarah Buxton Charlie Hannigan Fergus Kidd Nick Pestell Designers and c
34. d gently push the card into the Arduino the card holder is spring loaded and the card should decouple itself from the slot Gently pull the card out from the slot The data on the card is stored in a standard plain text file txt which can be read by any personal computer To retrieve this file named DATA the micro SD card must first be put into an adaptor that can fit into a personal computer Examples include a micro SD card to standard SD card adaptor which will fit into devices with SD card slots or micro SD to USB adaptors which fit all modern computers When the file is opened the top line should read Setup indicating that the system has set up correctly and established connection to the SD card If this is not shown refer to section 5 Under this should read the recorded data if an animal has used the device for more than the allotted equilibration time The data takes the form of X Number of animals X BMR X XXXXXXXXXX with XX readings taken mass X XX T XX XX User Guide UoB GIP 2012 13 Where X represents a digit The first Number displayed is the number of the data set taken Number of animals represents how many animals were in the box during the readings The BMR is the average BMR per animal in the box per day displayed in kCal day 1 The number of readings taken is the number of useful non anomalous readings taken after the waiting period that contributed to the average BMR The higher this numbe
35. data into a scatter graph On Excel this means selecting the two columns your data is stored in then going to the Insert tab gt Scatter gt Scatter with only markers j Nest right click on one of the data points on the chart and click Add Trendline then check the box Display Equation on chart and click close This should give you a formula for the line of best fit in the form y mx c where m is the gradient of the line and c is the y axis intercept User Guide UoB GIP 2012 13 These two values now need to be inserted into the main code so an accurate mass of the animals entering the nest box can be found The full code for OSCaR can be found in appendix I at the back of this guide and in the final few lines is the code for the scales Within this code there should be this couple of lines float gradient m float intercept c offset Where m and c are actual numbers from previous calibrations The values for the intercept c and the gradient m should be inserted in place of these previous values and the full code uploaded to the Arduino 6 Calibration of the scales is complete and the OSCaR device is ready for use with a new animal User Guide UoB GIP 2012 13 3 Retrieving Data The data generated by the electronics is stored on a standard 2GB micro SD card which is housed in a small metal adaptor slot on the Ethernet shield of the Arduino Make sure the device is powered OFF To remove the car
36. deelne eg ree eG eh has epi put Ros 10 5 Results 10 bel Waterproofing Tests 4 9 60084 tds e Poe Ba d de yg 10 5 1 1 Weathering Test cost 4 ist wate Ga aa ae wae oP X uso 10 5 12 Dunk Tests Aaa a Rae ae a Ween m S Gp ah Seale IC ee ee p M Let 11 5 2 Battery Life Testing 2 23 2 4 4 a4 eae SPEC AA Ge EE Pu Rh RR aes 11 5 3 Hamster BMR Investigation ees 11 5 4 Results from Bristol Zoological Gardens eA 11 5 5 Size Limiations cic ba a V5 XS we me Poe Wed Wu 12 5 5 1 Paraffin Wax Burner Effective BMR es 12 5 5 2 Oxygen Concentrations in Varying Box Dimensions and Varying Oxygen Consumption 12 iii 6 Discussion 13 6 1 Field Suitability Ci a a ee oh e k A Bee bie eh de OLE E Ren 13 6 1 1 Weatherproofing ii aeu ear en Dake a ee R Coe Ve e Gk e Ede A s 13 6 2 Power Supply s se t i had 22 24 6 ehh Stele ele ls A th k ea ae B EOS Bal a 13 6 1 3 Solar Panel Investigation u sou vo 20 em RR EE eor eee 14 6 2 Hamster BMR Investigation eee oso 14 6 3 Zoological Gardens was wd A Ng da RAA B EGP AA 15 64 Size Limitauons u even al zat nl ae EE EEE a Wh B edad o ee dem S Fe Ea seua Us s 15 6 4 1 Paraffin Wax Burner Effective BMR e a ee ss e 15 6 4 2 Oxygen Concentrations in Varying Box Dimensions with Varying Oxygen Consumption 15 0 5 b rth r Work nnn 60 bt mer A AE e ee addis A es 16 6 6 Market Research us s eee ee eeen a
37. e a 6 ua 16 6 6 1 Motivation 2 22E 5 48 46 6 Bee A eee dere a RB EDA Bal s 16 6 6 2 SULVeY zr iii VOV ea ola da da rete ete 316 LA oet oA Oe ee 16 6 0 37 Results 24 Ate 5 os deed de e de rl Mu eie usu OOS ous 17 6 64 Conclusion x ii EA C R6 AUR M a 30 AU SUS U ipse Ege 17 7 Conclusion 17 Appendices iii Appendix I Circuit Diagram iii Appendix II Complete Arduino Code 22s iii Appendix III Financial Report aoaaa aaa xiii Appendix IV Parts List with Suppliers 2 ee xiv Appendix V Travelling With Lead acid Batteries e r r rr re s s xiv Appendix VI Table of Component Power Consumption a a xv Appendix VII Tables of Steady State Waiting Times o xv Appendix VIII Zoo Survey Responses ee xvi Appendix IX User Manual xviii Appendix X Meeting Minutes 2l rs XXX V Appendix XI Certification of Ownership aa ee xli References xlii iv 1 Introduction Working in conjunction with Bristol Zoological Gar dens BZG the aim of this project was to build an instrument capable of measuring the basic energy expenditure of the grey mouse lemur Microcebus murinus a small nocturnal primate indigenous to Madagascar BZG is heavily involved in the con servation of endangered species of lemur and the development of breeding programs which are de signed to create a self sustaining captive population for
38. e load cell showing the measured voltage for a given mass Voltage on the Arduino is measured in arbitrary increments of 205V 1 7004 600 500 4 4004 300 4 Mass g 200 4 100 T T T T T T 0 200 400 600 800 Voltage arbitrary units Figure 3 Calibration graph for the load cell showing mass vs voltage the gradient of the line of best fit is 0 785 0 011 and the intercept is 24 51 0 35 Error bars are present but too small to be seen It can be seen in figure 2 that there is a promi nent kink in the data set of mass versus voltage the voltage goes up very slowly staying almost constant until about 200g at which point the gradient becomes much steeper The reason for this is hard to consider but suggests there are two flexing regimes in the scale mechanism This is probably due to the wood and plastic support underneath the load cell which may flex before the load cell does This discontinuity in the graph gradient complicated matters and reduced the resolution of the scales at low masses it was there fore decided to load the scales with enough weight to reach the point at which the gradient steepens This was achieved by attaching approximately 200g in mass to the underside of the weighing platform With this extra mass attached the calibration was carried out again giving figure 3 The equation of the line of best fit of figure 3 mass 0 785V 24 51 was then used in the Arduino c
39. e paraffin wax burner 15 6 4 2 Oxygen Concentrations in Varying Box Dimensions with Varying Oxygen Con sumption To use the technique developed in this project the system must satisfy certain conditions Firstly it is required that the system reaches steady state before any measurements of oxygen concentrations can be used in the calculation of BMR Therefore it is nec essary that T is relatively small in comparison to the time for which the nest box is occupied By analy sis of the table in appendix VII it is seen that T is decreased by decreasing N decreasing V decreasing L and increasing A While the time taken to reach steady state is an important factor in considering whether this technique may be applied to a certain species within the range of these tests T remains within a practical value so long as the species in question typically occupies their nesting box for peri ods longer than 10 minutes T may become too large however for animals that use large nest boxes with small entrance holes or for very large animals Much more significant is the consequence of back ground noise The difference between oxygen concen trations inside and outside the box must be large with respect to the level of fluctuations Ultimately the technique developed through this project will become unsuitable for species where the level of BMR is low and the volume of the nesting box is comparatively large as is modelled by box 11 F
40. e shown that metabolism of some mammals is el evated by up to 65 for two hours after human con tact and measurements taken during this relaxation period will not be true indicators of BMR 2l This necessitates the use of the indirect calorimetry dis cussed next 2 4 2 Indirect Calorimetry Indirect calorimetry is widely regarded as the gold standard method for measuring BMRI l It depends on the measurement of some parameter related to energy expenditure other than heat production Among the techniques of indirect calorimetry respirometry is one by which measurements of the rate of oxygen consumption or the rate of carbon dioxide production are related to energy expenditure In the process of aerobic respiration Animals inhale oxygen from the air in order to oxidize organic com pounds which in turn releases the chemical energy stored in the bonds I9l CeHi2 602 6C0O3 6H20 AG 686kcal mol 3 The total amount of energy released in the oxi dation of 1mol of glucose shown above is 686kcal Gibb s free energy In cellular respiration 420kcal is released as heat and the remaining 266kcal is trans ferred as chemical energy to the molecule ATP to be used for other physiological functionsl l Much of the difference in oxygen necessary to metabolise the three predominant food groups is counteracted by differing releases of energy from their oxidation This means that the calorific value per litre of o
41. een raised from its BMR which is represented in the results recorded The error value of 2 8 kcal day was calculated by combining the errors associated with each vari able in equation 11 As mentioned in section 2 4 2 the error associated with using a value of 4 8 kcal I is 6 The error in oxygen concentrations and temperature are assumed to be the resolution of the LuminOx oxygen sensor 0 01 and 2 degrees re spectively The errors in the radius of the entrance hole and the entrance hole length are 0 05mm The error in the diffusion coefficient was calculated using regression analysis of the straight line given by equa tion T The hamster test also proved the capability of the animal detection system with live animals which worked flawlessly but raised issues of power capabil ity as potential data was forfeited due to the device loosing power earlier than expected in the 48 hour testing period 6 3 Zoological Gardens The main issue with recording data with the mouse lemurs in the zoo enclosure was neophobia Animals in captivity are known to be more neophobic than wild animals and this neophobia has been recorded in previous attempts to measure the BMR of these lemurs although this device was left for a much longer time period than in these attempts 118 The lemurs were much more inquisitive about the box whilst it was in the position that they are accustomed to using a standard nest box Howeve
42. ent that could charge the battery when it was sunny A typical circuit for this is shown in figure 15 Such a set up could be created for around 60 using Solarex 7 5V Solar Cells from RS Components and would greatly extend the running time of the sys tem A small simulation was run using climate data from the west of Madagascar a typical field location for the box to calculate how long the device could last with a 15Ah battery and 300mA of solar cells Depending on the time of year this could extend bat tery life to be between 8 and 41 days with 21 days 3 weeks being the average which should be adequate for most field studies It is also likely that these esti mates are conservative as they were made using just sunshine hours not considering the fact that solar cells will still generate some power even when it is cloudy 6 2 Hamster BMR Investigation The result of the measured BMR can be directly compared to a previous more in depth investiga tion of the BMR of the Djungarian hamster using flow through gas respirometry The result from this method gave a BMR of 17 28 kcal day 1 5l This result is slightly lower than the observed result in the OSCaR of 22 4 2 8 kcal day However this is expected as the hamster subject was not in the device long enough to be truly at rest and had not been iso lated from food to neglect effects of digestion These factors would have caused the actual metabolic rate of the hamster to have b
43. epers have no accurate method of knowing an animal s daily energy expenditure and it can take a period of time before the negative impact of overfeeding becomes apparent Using a calorime ter avoids this lag time and provides a live value of BMR It is also a useful tool for zoologists as drug dosages can be administered based on an animal s metabolic ratel l Dr Schwitzer Head of Research at BZG has also expressed interest in using the de vice to conduct research into daily torpor which is the regular period of decreased physiological activity and thus metabolic rate which lemurs undergo in order to conserve energy There is no product like this on the market There are invasive and expensive methods of calorimetry available but even if BZG was prepared to use these they contravene Home Office regulations This is an exciting project if successful in creating a non invasive measurement device it will be the first of its kind 2 3 History The earliest and simplest measurement device was de veloped by Antoine Lavoisier and Pierre de Laplace and was built in the 1780s It consisted of a well insulated chamber surrounded by densely packed ice The apparatus was completely sealed save for a mod est air pipe which allowed the occupant to breath The animal was placed inside the chamber and heat and therefore energy lost by the subject was calcu lated from the mass of the collected water and the latent heat of melti
44. er Supply Dr Schwitzer expressed concern that the type of battery 9V PP9 used in the demonstration of equipment would not be readily available in Madagascar and that international air travel with batteries would not be a suitable alternative Action Group Replace PP9 battery with a series of smaller PP3 batteries which Dr Schwitzer suggested are readily available in madagascar Research more into the use of solar panelling 3 Extended Applications of the Device Dr Schwitzer asked about the possibility of using the device with mains power in the zoo to monitor BMR changes with varying temperature over a period of a year Action Group Research mains power adaptation to the system Add a temperature reading on the output data saved to the SD card 4 Next Meeting A preliminary window of dates for the final project presentation was given for the week beginning the 13t of May Meeting with Dr Schwitzer to place equipment in enclosures at BZG to be arranged at a convenient time Action Sarah Buxton El e Ke University of ES BRISTOL School of Physics Bristol Zoo Gardens Group Industrial Project Meeting Extension Problems Date 28 02 2013 Location H H Wills Physics Laboratory Chairperson Nicholas Pestell Secretary Fergus Kidd In Attendance Professor Peter Barham Project Supervisor Charles Hannigan Treasurer Sarah Buxton Communications Officer 1 Project Brief Professor Barham proposed that although the pro
45. ers to collect research passes from BZG membership office 2 Accessing Keepers Dr Sue Dow proposed that she be point of contact for all zoo keepers should members require any information or action from keeping staff Action Sarah Buxton 3 Zoo Familiarisation Dr Sue Dow proposed a brief tour of Bristol Zoo Gardens specifically twilight world to familiarise project members with layout of the zoo and the location of the test animals discussed in the meeting of 12 11 2012 Action Members receive tour 4 Next Meeting Deferred until further notice El e Ke University of ES BRISTOL School of Physics Bristol Zoo Gardens Group Industrial Project Meeting Diffusion laws Date 20 02 2013 Location Centre for Nanoscience and Quantum Information Chairperson Charles Hannigan Secretary Fergus Kidd In Attendance Prof Heinrich Hoerber Professor of Nano biophysics and supervisor of previous Bristol zoo projects Sarah Buxton Communications Officer Apologies Nicholas Pestell 1 Diffusion Laws Sarah Buxton proposed discussion of gaseous diffusion models in application to experimental corrections of BMR and the use and application of Fick s laws Action Prof Hoerber suggested Fick s first law although not strictly physically representative of the actual system would be enough to make initial estimations of the oxygen diffusion He also suggested researching the speed of diffusion of oxygen in air 2 Calibration of
46. espectively P is the pressure in Pa R is the gas constant in JK mol and T is the temperature in K The factor of 100 in the denominator converts the oxygen concentrations to fractions and the quantity is the number of moles per m of air from the ideal gas law By substituting for J into equation 6 the oxygen consumption in mol s can be found 9 In order to use the newly found oxygen consump tion in equation 4 it must first be converted into units of litre per second this is performed as follows RT O2 Consumption 1 1 1000 x Oz Cons mol s 10 10 S 2 AD x The quantity a converts moles into m and 1000 is the conversion factor for m into litres Substitution of oxygen consumption into equation 4 gives the final equation for BMR as used in this project C5 Ci BMR kcal s 1 48 x AD 11 3 4 Calibration and Design Testing 3 4 1 Scale Calibration Once the scales were installed in the base of the nest box they needed calibrating against a set of test masses This was done by connecting the scales and accompanying amplifying circuit to the Arduino and creating a graph of voltage against mass from which an equation linking the two could be found This graph is shown in figure 2 below 8004 700 600 500 400 3004 Voltage arbitrary units 2004 1004 1 REA r 04 T f T T T T 0 100 200 300 400 500 600 Mass g Figure 2 Initial calibration graph for th
47. g this before flying Unfortunately it is at the discretion of security as to what goes through the checkpoints and they have the power to confiscate anything they deem to be dangerous or potentially alarming to other passengers so these precautions do not guarantee being able to travel with the battery A safer idea is to send a battery ahead to its destination with a courier such as FedEx or UPS A further note Lithium Ion batteries of the necessary capacity to run the device are not permissible in any form on board aircraft due to current regulations Xiv Appendix VI Table of Component Power Consumption Table of power consumption of components that make up the OSCaR Current Per Curent Quantity Component Drawn SS R LEDs Amplifier Trigger i a Ee es Appendix VII Tables of Steady State Waiting Times Results of equilibrium time for each box burner combination with details of dimensions of the boxes and the number of 10g paraffin wax burners used in each box All errors calculated using standard error in mean Box 1 Box 2 Box 3 Box 4 Box 5 Box 6 Box 7 V m 0 00670 0 00670 0 00670 0 00670 0 00670 0 00670 0 0353 0 00003 0 00003 0 00003 0 00003 0 00003 0 00003 0 0002 A m 0 001963 0 001963 0 001963 0 001963 0 001963 0 001963 0 001963 0 00008 0 00008 0 00008 0 00008 0 00008 0 00008 0 00008 L m
48. gations under copyright legislation i e that no quotation and no information derived from it may be published without the author s prior consent Authors S L Buxton C S Hanngian F E Kidd and N J Pestell Title Non intrusive measurement of Basal Metabolic Rate using an Open System Calorimetry Respirometer OSCaR Date of Submission 09 05 2013 Signed Sarah Buxton Charles Hannigan Fergus Kidd Nicholas Pestell Full names Sarah Buxton Charles Hannigan Fergus Kidd Nicholas Pestell Date 09 05 2013 This project is the property of the University of Bristol Library and may only be used with due regard to the rights of the author Bibliographical references may be noted but no part may be copied for use or quo tation in any published work without the prior permission of the author In addition due acknowledgement for any use must be made xli References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 D Randell W Burggren amp K French K Animal Physiology Mechanics and Adaptions 4th Edition W H Freeman and Company pp 666 667 661 674 668 79 81 669h A J Hulbert and P L Else Basal Metabolic Rate History Composition Regulation and Usefulness Physiological and Biochemical Zoology 77 6 869 876 2003 M Gordon Animal Physiology Principles and Adaptations Macmill
49. gen consumption and similar nest box dimensions The dimensions of the boxes and the number of paraffin wax burners used in each 10 box are shown in appendix VII 5 Results 5 1 Waterproofing Tests 5 1 1 Weathering Test Figure 5 The epoxy treated wood shows little sign of degradation while the non treated con trol piece has become discoloured and has had pieces fall off around the edge upon handling after the experiment suggesting fragility Figure 6 It is clear that cracks have appeared parallel to the grain lines in the original pieces of wood that make up the laminations It should also be noted that delamination of the layers in beginning to occur The accelerated weathering of the differently treated wood types yielded significantly different results af ter 2 weeks of wet dry cycling Figure 5 shows a side by side comparison of the two pieces Other is sues become apparent with the control sample when viewed along the laminations as seen in figure 6 Comparatively neither of the effects in figure 6 can be seen in the wood that was coated with epoxy resin shown in figure 7 Epoxy Resin Figure 7 The epoxy coating appears to have kept water out of the wood leaving it in a bet ter condition after weathering 5 1 2 Dunk Tests The dunk test of the control box was carried out twice The first test yielded approximately 6mm of water in the bottom of the box after 30 minutes which equates to approx
50. gether These two measurements must then be inputted into the code in the Arduino The Arduino is accessed through a custom program which is downloadable from the Arduino website http arduino cc en Main Software along with instructions on how to set it up for use After installing the program open a blank file and copy the code from Appendix l into it inserting the variables that you measured previously in the relevant places which are found near the top of the program const double Area e g 0 0022 Area of entrance in m 2 const double Length e g 0 002 entrance length in metres The Arduino can then be plugged into the computer using a USB cable at this point there is no need for an external power supply for the Arduino as it is powered through the computer Once the Arduino is connected the upload button a circular button with an arrow pointing right should be pressed to send the altered code to the device if the program asks you to save the sketch before uploading do so The Arduino can now be disconnected from your computer and connected to the outside power source usually a battery User Guide UoB GIP 2012 13 2 2 2 Light Gates When changing the OSCaR onto a new nest box the false panels that conceal the light gates in the entrance to the nest box need to be replaced with appropriately sized ones The steps for this are as follows 1 Cut two panels identical to the existing entrance panel on the front of t
51. had to be purchased separately so was essentially a bare bones SD card reader writer a device like this could approximately halve power draw to 150mAh A separate advantage of one of the third party options is that they use normal sized SD cards which are much cheaper than their micro SD counterparts The other reason for short battery life was that at the time of finalising cuts for the instrumentation box a combination of a lower expected power usage and unrealistic expectations about battery technology in terms of energy density led to too little space being allocated for batteries If the control box were made approximately 50mm longer it would give space for a 15Ah lead acid battery which when combined with power saving measures outlined above could give a running time of 100 hours approximately 4 days 6 1 3 Solar Panel Investigation 7 5V 200mAh 7 5V 200mAh Zener Diode Ne r Arduino Power Jack Figure 15 An example circuit for solar charg ing the instrument batteries The Zener diode prevents the batteries discharging over the cells at night and also helps prevent overcharg ing by allowing charge flow to reverse if the battery voltage becomes too high The estimated battery life even with a larger battery and lower power consumption was still not ideal so 14 it was decided to carry out an investigation as to practicalities and cost efficacy of adding solar cells to the instrum
52. he nest box including the entrance hole 2 On one panel mark out where the first set of light gates will lie across the box s entrance hole They should be directly opposite to each other as they rely on line of sight 3 On the front panel of the nest box do the same ensuring that the position of these light gates is approximately 90 offset from those in step 2 4 Additionally channels should be marked out on both panels where the light gate wiring will run These channels should start at the markings made in previous steps and terminate in the same area near the edge that will be adjacent to the OSCaR control box in the area where the light gate wiring hole in OSCaR is 5 Use a chisel to form the channels and holes marked out previously making them deep enough to contain the necessary LEDs light sensors and wiring in practice this means channels about 5mm deep 6 Inthethird un chiselled panel cut a small square out of the edge in line with the appropriate hole in OSCaR This square should also line up with the ends ofthe wiring channels cut in step 5 7 Now insert the LEDs and light sensors that make up the light gates into the channels there should be one light sensor and one LED in each of the two panels and they should be placed opposite each other The wiring should then be run down the channels followed by the whole set up being secured with silicone sealant This helps keep everything in place as well as waterpr
53. hows that the diffusion coeffi cient as an approximation varies linearly with tem perature from 17 9 0 895 x 10 9m s at 0 C to 22 741 135 x 10 5m s at 40 CP l giving the fol lowing relationship between D and T D 1 2x 1077 x T 1 488 x 107 7 Where T is in degrees Kelvin There is an error associated with the two values in 7 however these are insignificant in comparison to the values them selves The diffusion coefficient also has a dependence on pressure however over the altitude range at which this device will be used the pressure dependence can be neglected 3 3 3 Derivation of Final Equation As outlined in section 2 4 2 an estimation for the BMR can be made via equation 4 This forms the basis of the calculation used in this project Assum ing the system has reached steady state the amount of oxygen consumed per second in 4 is given by 8 Where J is the flux in mol ms and A is the area of the entrance to the nesting box in m The O gt consumption JA flux is calculated using Fick s law as described in sec tion 3 3 1 A few subtleties in the formula for J arise due to unit conversions ge should be in units of mol m however oxygen concentration provided by the LuminOx sensor is as a percentage hence the follow ing adaption of Fick s law is used J Soe zy 100X RT Where C and C2 are oxygen concentrations in parts per hundred outside and inside of the nesting box r
54. i dence varies so much that some experts have rejected both exponents Whether data supports a power of 2 or 3 there is certainly no unilateral agreement on the relation and markedly less agreement on the explanations behind the relations For this reason it is necessary to experimentally measure rather than estimate an individual s metabolic rate 2 4 Methods of Measurement 2 4 1 Direct Calorimetry Methods of measurement can broadly be split into two groups direct and indirect calorimetry Direct calorimetry involves measuring the total amount of heat produced by an animal and equating this to its energy usage The method relies on Hess s law which states that the total energy released in the breakdown of a fuel to a given set of end products is always the same irrespective of the intermediate steps or pathways used The corollary of this is that when no physical activity is being carried out and no new molecules are being synthesized the total chemical energy released by an animal in performing its metabolic functions ultimately appears as heat The earliest measurement via direct calorimetry was that of Lavoisier and Laplace discussed in section 2 3 The main problem with direct calorimetry is that it is invasive as the animal does not enter and leave the chamber under its own free will this necessitates cap turing the animal which will artificially raise its BMR due to the physiological stress of handling Studies hav
55. icer 1 Project Brief Professor Barham proposed that although the project brief was not certain yet it would be about metabolism in the form of an electronics and programming exercise and that the group should investigate microprocessing and sensor types as well as becoming familiar with a suitable programming language Action Group 2 Required Skills Professor Barham suggested that the group assign internal roles and acquire the relevant skills to fulfilling the given role Roles include chairperson treasurer secretary and communications officer He also suggested researching some level of zoology and biology to become familiar with the basics that will be required to investigate metabolic rates Action Group 2 Zoo Contact Professor Barham proposed that Dr Christoph Schwitzer head of research at Bristol Zoo Gardens be contacted for a meeting about possible project briefs Action Sarah Buxton Plc University of CAPS BRISTOL School of Physics Bristol Zoo Gardens Group Industrial Project Meeting Project Brief Date 12 11 2012 Location Bristol Zoo Gardens Chairperson Nicholas Pestell Secretary Fergus Kidd In Attendance Dr Christoph Schwitzer Head of Research BZG Prof Peter Barham Group Supervisor Sarah Buxton Group Contact Charles Hannigan Treasurer Apologies N A 1 Project Brief Dr Schwitzer proposed that the brief of the project be the design and production of a device to measure the basal me
56. ics 1 2 205 209 2004 R Pannorfi B M Zee I Vatnick N Berner amp S M Hiebert Dietary Lipid Saturation Influences Environmental Temperature Preference but Not Resting Metabolic Rate in the Djungarian Hamster Phodopus sungorus Physiological and Biochemical Zoology 85 405 414 2012 R Mittermeier E E Louis Jr M Richardson C Schwitzer et al Lemurs of Madagascar Third edition Conservation International p 116 117 2010 xliii
57. ifference between inflow and outflow is a measure of oxygen consumption In their traditional forms both open and closed system respirometry offer the same disadvantages as associated with direct calorimetry that is to enclose an animal in an unfamiliar environment which is likely to increase stress and remove the animal from basal conditionsl l As a variation to the closed system respirometry technique for small animals using nesting boxes such as the Grey Mouse Lemur the system can be built around a nesting box similar to that which the an imal would normally use Thus the animal should enter of its own volition Not only is this in keeping with the BZG research policy but it also allows for a more accurate measurement of BMR by ensuring that the animal is under minimal stress and therefore is as close as possible to basal conditions 2 5 Previous Work at the University of Bristol This project is a continuation of similar work car ried out by three previous groups at the University of Bristol Most recently progressions were made in 2011 by G Cohen and J Humphries lll The aim of their project was to develop an instrument capable of measuring the BMR of the Grey Mouse Lemur in the zoo and in their natural habitat of Western Madagascar 2011 was the first year it was proposed that the device should be taken to Madagascar for use in the field hence notable developments were to be made in portability and durability
58. igure 12 shows that for this type of system fluctuations in the oxygen concentrations are too great to establish steady state Box 12 has the same dimensions as box 11 however it contains 4 more burners It can be seen from figure 13 that steady state is established in box 12 and the fluctuations are relatively small in comparison to the difference between oxygen concentrations inside and outside of the box Box 12 contains 7 burners this is representative of an animal with a BMR of approx imately 91 kcal day This corresponds to a mass of 1 4kg using equation 2 It is therefore concluded that to use the technique developed in this project 1 4kg is an approximate lower bound for the mass of an animal inside a box of volume approximately 0 1m Animals of lower mass may be considered by lowering V as demonstrated by the lower levels of noise observed in figure 9 compared with figure 10 Alternatively animals of lower mass may be consid ered by lowering A demonstrated by the lower levels of noise observed in figure 11 compared with figure 12 or by increasing L demonstrated by the lower lev els of noise observed in figure 14 compared with figure 13 6 5 Further Work From the results of the investigation in section 6 1 3 it is clear to see that further research into solar pow ering the OSCaR would be a very useful extension In order to leave the OSCaR inside the lemur en closure without attendance and for extended periods of
59. imately 135ml and a flow rate of 0 075ml s It was thought that this leakage was most likely coming in through the corner seals of the door which were subsequently improved and the box re tested This test yielded less than 1mm of water after 30 min utes 5 2 Battery Life Testing Using a multimeter to measure the current from the power source to the Arduino suggests that the whole system draws between 270 and 300mAh the higher the voltage of the battery the higher the current This is most likely due to the power loss from the regulation of voltage to 5V which increases with voltage above 5V Taking a conservative estimate this current yields a battery lifetime of 3 3 hours per 1000mAh there 11 fore a 10000mAh pair of PP9 batteries would last approximately 33 hours while the 4000mAh lead acid batteries used would give about 13 hours of operation The measured current draw tallies very well with the theoretical estimation obtained by adding up the specified power consumption of all the system compo nents which came to 298 5mA A full table of these results is shown in appendix VI 5 3 Hamster BMR Investigation The hamster test subject used the device readily and became comfortable in the device for the duration of the test period entering and exiting the device at will and crucially spending a reasonable amount of time in the device 21 85 N N Oxygen Level in Chamber Average Backgr
60. iving a plastic like finish to the wood that was both tough and wa terproof 3 1 10 Animal Proofing Several animal proofing measures were taken in build ing the instrument for the safety of the animals and the longevity of the equipment These were as follows e The oxygen sensors were covered in wire mesh to prevent animals being able to come into con tact with them e The instrument box had clips attached to its door to prevent access to electronics e All light gate wiring was built into false panels at the front of the nest box e All wiring related to scales was run through the false floor of the nest box e As previously mentioned all circuitry was well waterproofed to prevent electrical dangers to animals 3 2 Code The Arduino was coded in a language very similar to C The code comprises of a set of switch functions able to determine the direction of movement through the LED gate setup for the first animal to enter After an animal is detected a loop is entered in which oxy gen percentage and temperature readings are taken every 10 seconds An important feature of the code is that the loop is comprised of tens of thousands of tiny time delays rather than one large one per read ing interval which allows for the constant monitoring of the LED gate system so the system will always be able to detect an animal leaving or a second enter ing In these events the system averages all the data calculates the BMR
61. ject brief was not certain yet it would be about metabolism in the form of an electronics and programming exercise and that the group should investigate microprocessing and sensor types as well as becoming familiar with a suitable programming language Action Group 2 Required Skills Professor Barham suggested that the group assign internal roles and acquire the relevant skills to fulfilling the given role Roles include chairperson treasurer secretary and communications officer He also suggested researching some level of zoology and biology to become familiar with the basics that will be required to investigate metabolic rates Action Group 2 Zoo Contact Professor Barham proposed that Dr Christoph Schwitzer head of research at Bristol Zoo Gardens be contacted for a meeting about possible project briefs Action Sarah Buxton Appendix XI Certification of Ownership Project Report presented as part of and in accordance with the requirements for the Final Degree of BSc at the University of Bristol Faculty of Science I hereby assert that I own exclusive copyright in the item named below I give permission to the University of Bristol Library to add this item to its stock and to make it available for consultation in the library and for interlibrary lending for use in another library It may be copied in full or in part for any bona fide library or research worked on the understanding that users are made aware of their obli
62. le txt Serial println lemnum if lemnum 0 ix interceptOffset analogRead A2 E 0 variable to recalibrate the scale to zero when no lemurs are preser if lemnum gt 15 counter error happens when the line of sight between LED and detector is on a slight angle E 1 lemnum 0 if lemnum lt 0 counter error happens when the line of sight between LED and detector is on a slight angle E 2 lemnum 0 if t 0 amp amp k 0 calculates and prints BMR after last animal leaves dataFile SD open data txt FILE WRITE if the file is available write to it if dataFile Run 1 BMR BMRsum k numnow BMRday 86400 interval BMR print all data collected to SD Serial print Run dataFile print Run Serial print dataFile print Number of animals Number of animals dataFile print numnow K Serial print numnow Serial print BMR dataFile print tBMR Serial print BMRday 10 dataFile print BMRday 10 Serial print t with dataFile print t with Serial print k dataFile print k Serial print readings taken mass masssum k numnow Serial print tmass dataFile print readings taken Serial print mass dataFile print tmass dataFile print mass Temp 2 Serial print tT Serial print tempout dataFile p
63. low or very variable initially then the LED and sensor aren t properly aligned you should adjust their positions within the channel until you are happy they are aligned as in step f h Repeat the above steps for the other light gate panel 9 The panels can now be secured to the front of the nest box and the relevant wires inserted into the instrument box 10 The light gates now need to be permanently wired in inside the OSCaR control box there is a circuit board with several screw pin terminals soldered on to it There should be two free screw pin terminals marked with a and a the red wires of the light gates should be attached to the side of these terminals and the black wires to the side The two white signal wires of the light gate pair should be attached directly into analog pins AO and A1 User Guide UoB GIP 2012 13 2 2 3 Scales As with the light gates the scales cannot be taken straight from one nest box and inserted into another The platform of the scale must fit snugly into the bottom of a nest box so as to minimize detritus getting into the scale mechanism and make the box as normal as possible for the animal The scale consists of a wooden platform screwed to a load cell which is then combined with a plastic base and bolted to the bottom of the nest box The steps for altering this set up for a new box are as follows 1 Measure the internal dimensions of the bottom of the nest box and cut a piece of plywood to be
64. mote field work it would be possible take just the instru ment and then attach a nest box in situ thus saving weight and space which may be restricted when trav elling The design of the nest and instrumentation box is shown below in figure 3 1 Instrumentation box Nest box Figure 1 Basic nest instrumentation box design of the For the instrument to be capable of measuring BMR it needed a pair of oxygen sensors one mea suring Os concentration outside the nesting box and one inside and a small computing unit Addition ally light gates at the nest box entrance provided presence detection and built in scales allow exten sions of research to allometric scaling laws which rely on knowing an animal s mass l 3 1 1 Nesting Box The design of the nesting box was based very closely on one BZG uses with their lemurs with all dimen sions being as close as possible to the box that was already in use this was to maximise the familiarity of a new box to the lemurs Some instruments ne cessitated slightly different measurements which are mentioned in sections 3 1 6 and 3 1 7 Each change was approved by Dr Schwitzer who was capable of judging what if any impact the difference would make on the lemur s welfare and likelihood to use the next box The material used was plywood the same mate rial as the zoo s box specifically it was water and boil proof WBP plywood which is resilient to water
65. ng ice l In principle this method was simple though in practice it was cumbersome and expensivel l Historically the BMR of an animal has been esti mated using formulae based on allometric laws that is to say laws which relate the geometry of a crea ture to its physiology The earliest equations propos ing BMR as a function of body mass were devised by Max Rubner in 1883 who concluded that BMR scaled with mass to the power of two thirds Rub ner s derivation was underpinned by the theory that BMR is proportional to heat output and thus surface areaP l He made numerous assumptions including that an animal is spherical and his work fell under experimental scrutiny Half a century later in 1932 Max Kleiber empirically showed a closer relation of basal metabolism to the three quarter power of body weight than to the geometric surface of an animal a relation that came to be known as Kleiber s law BMR aM 2 Kleiber found a the constant of proportionality to be an average of 70kcal kg day for mammals 4 This exponent was the most commonly accepted value of the scaling factor for the majority on the 20th century but the validity of the Kleiber exponent has recently been under further scrutiny The in tercept and exponent are of course both approxima tions with 3 chosen as much for convenience as for accuracy and have been shown to be sometimes sig nificantly different depending on specieslfl The ev
66. no resin on it The reasoning was that being sub merged constantly in water for long periods of time would accelerate any weathering that may occur in the field particularly in warm wet Madagascar and thus show us the efficacy of the epoxy resin in protect ing the wood and therefore the electronic equipment from the elements The expected result was that the control piece would swell and warp much faster than the coated piece After several days submerged it was realised that this was not true weathering as generally the wood will be only periodically wetted followed by dry peri ods which may in fact put greater stresses on the wood and cause it to deform more Therefore the experiment was changed to recreate such conditions the wood was left to soak during the working day approximately 8 hours and then taken out to dry overnight This gave a rough ratio of dry time to wet time of 2 1 Once the control box was built the overall design was also tested for weatherproofing This test con sisted of a prolonged submersion approximately 30 minutes of the box in a tank of water followed by measuring how much water had managed to seep in 3 4 3 Power Source Testing To get an idea of how long a particular battery would run the device for its power consumption was mea sured This was a simple measure of the current being drawn from the battery using a multimeter This current was then easy to change into a time this is be
67. o measure interior oxygen concentration while the other was placed through the floor of the instrument box to measure exterior concentration for comparison 3 1 6 Light Gates Grey mouse lemurs especially the females tend to nest in groups this means that there could be several animals in one nest box at a time Consequently a way of counting the number of lemurs in the box was necessary so a BMR for each animal could be cal culated this had the additional advantage of being able to tell when the nest box was unoccupied thus meaning that recordings would only be taken when an animal was present and also allowing a power sav ing mode to be entered in the meantime In this project a pair of light gates were set into false panels at the front of the nest box entrance but were placed with at different depths within the en trance hole these panels necessitated increasing the depth of the nest box entrance hole This allowed the direction in which the animal moved through the hole to be ascertained depending on what order the two gates were triggered intermediate stages such as if an animal entered the entrance hole but turned back could also be discerned further reducing any errors in animal count Each light gate was made up of an infrared LED directly opposite a Schmitt Trigger which is an opti cal sensor that reads a binary state depending on the flux of the infrared light falling on it a high voltage at high flux and
68. o be implemented on nu merous species besides the Grey Mouse Lemur As an extension to the design of the OSCaR the scope of the technique was examined with respect to size of the animal To model the respiratory rate of an animal the oxidation of paraffin wax by combustion was used This reaction both consumes oxygen at a given rate as well as exuding heat much the same as a warm blooded mammal of the type under investigation Using this model it is possible to test the theory and equipment without using live animals in the labora tory Firstly an effective BMR was calculated for a single 10g paraffin wax burner that is the value obtained from equation 11 from a single paraffin wax burner inside the OSCaR This is so that a com parison between a particular animal and a certain number of paraffin wax burners can be made Three 10g paraffin wax burners were measured and an av erage value was used To simulate animals with different sizes card board boxes of varying volume V entrance hole area A and entrance hole length L were used in replacement of the OSCaR nesting box Varying numbers of paraffin wax burners N were placed inside the boxes to simulate animals of varying res piratory rates For 14 different combinations of box dimensions and number of burners 5 plots of oxygen concentra tion vs time were made The plots were studied to assess the feasibility of using the technique on an imals with similar oxy
69. ode to convert the measured voltage to a mass of the animal As well as the kink in the calibration graph an other interesting property of the scale system was that the values it gave fluctuated not randomly but in the fashion of a damped harmonic oscillator an example of this is shown in figure 4 e l Voltage arbitrary units 5047 T T T T 1 200 400 600 800 1000 Time ms odt Figure 4 The oscillation of the load cell volt age reading with time after the addition of a 50g weight showing the exponential decay in oscillation amplitude The time constant in this case is approximately 100ms but is likely to be proportional to the applied mass as is the case with harmonic oscillators This is a well known artefact of load cells known as ringing which is due to the physical vibration of the metal bar that makes up the cell With har monic oscillation the equilibrium point of the fluctua tions is the true value for the given mass so averaging over a significant period of time smooths out the vari ation and gives an accurate value which was done in the section of code responsible for measuring mass 3 4 2 Testing Waterproofing As a crude measure of the durability of the control box a small qualitative experiment was carried out a sample piece of wood was coated in epoxy resin as the equipment box was to be and submerged in a beaker of warm water along with a control piece that had
70. ol Station 5 18 Tool Station 0 17 Tool Station 6 48 Tool Station 0 50 RS Components 0 55 RS Components 0 91 RS Components 3 32 RS Components 2 99 RS Components 5 00 Maplin Epoxy Coating Resin 500g Pack Eveready PP9 Zinc Carbon 9V battery Brass Plated Hinges Spray Paint Matt Black PEX Insert 22mm Weatherstrip P profile brown DC power cable mount plug 2 1mm PCB mount DC power socket 2 1mm Press studs for PP9 cell pair SD5620 OptoSchmitt Detector Spring loaded mini steel toggle latch Transcend 4Gb Micro SD card with reader Appendix V Travelling With Lead acid Batteries Most modern lead acid batteries are suitable for air travel but this does not necessarily mean they will be cleared to go on board The important specifications to look for in the datasheets for the battery which can be found on the manufacturer s website are that e It is sealed or non spillable e It has gas recombination technology e It has a power capacity of less than 100Wh equivalent to 16600mAh for a 6V battery or 8300mAh for 12V If attempting to take batteries while air travelling the battery should be taken in hand baggage its terminals should be insulated e g by taping them and the battery data sheet should be carried with it along with a print out of the air carrier s restrictions to demonstrate it is an allowable item It may also be advisable to contact the carrier regardin
71. oofing the electronics 8 Asthe silicone dries it is important to make sure the light gates are finely aligned Do this one panel at a time a First plug the Arduino into a computer using a USB cable b Power up the LED this means connecting a 4700 resistor to the black wire ground then connecting this to the pin marked GND on the Arduino The red wire positive should be attached to the pin marked 5V on the Arduino User Guide UoB GIP 2012 13 c Likewise the light sensor also needs power As in step b the black wire of the light sensor should be connected to the second GND pin via a 4700 resistor and as there is only one 5V pin on the Arduino the red wire of the light sensor should be connected to digital pin 7 The white signal wire should then be connected to analogue pin AO d Now open the Arduino software and paste in the following code int lightSensor 7 void setup Serial begin 9600 pinMode led OUTPUT void loop digitalWrite lightSensor HIGH int sensorValue analogRead A0 Serial println sensorValue e Upload the code to the Arduino and then open the serial monitor Ctrl Shift M f Ifthe LED is properly aligned with the sensor then you will see a fairly constant list of high numbers gt 1000 printed in the serial monitor this should be double checked by blocking the LED with a finger and checking the listed numbers step to a much lower value lt 750 g Ifthe numbers are
72. or opening file txt else if t gt 13000 amp amp t 6500 0 main data reading sequence Percentage Temp Serial print O2 inside Serial print percentin Serial print t t Serial print O2 outside Serial print percentout Serial println 96 dataFile SD open data txt FILE WRITE if dataFile dataFile print percentin dataFile print 1t dataFile println percentout dataFile close if the file doesn t open pop up an error else Serial println error opening file txt avtemp tempin tempout 2 273 15 convert to Kelvin D 0 12x avtemp 14 878 pow 10 6 BMRnow percentout percentin Length D 48 57 interval Area f BMRnow gt 0 amp amp percentin gt 5 BMRsum BMRnow Serial println BMRsum 10 masssum massFinder interceptOffset k 1 else if percentin 5 amp amp percentout gt 5 masssum massFinder interceptOffset k 1 i f t 26000 t 19500 start monitor animal detection in this loop if analogRead sensor0 lt 600 mouse lemur in entrance array 0 else if analogRead sensor0 gt 600 no mouse lemur in entrance vii array 0 0 if analogRead sensorl lt 600 mouse lemur in entrance array 1 1 else if analogRead sensorl gt 600 no mouse lemur in entrance array 1 0 switch state case 1 a array 0 1 amp
73. ound Level Oxygen Concentration N N N E pa P ES o N e w 21 2 50 100 150 200 250 300 Time s Figure 8 Oxygen level vs time for hamster Error bars from sensor resolution The variation of oxygen in the device from the res piration of the hamster is as expected The drop to steady state can be seen in figure 8 occurring after only about 190 seconds BMR calculations that were made after this 190 seconds using the methods shown in sections 3 2 and 3 3 3 and gave the BMR of this hamster to be 22 4 2 8 kcal day 5 4 Results from Bristol Zoological Gardens Originally the device directly replaced the nesting box already in the enclosure secured to a section of tree branch Unfortunately the branch itself was unable to safely support the weight of the device leading to the immediate removal of the device from the branch af ter two days for the safety of the animals The device was then placed on supports on a shelf at the back of the enclosure where the lemurs are fed In the period of these four weeks the mouse lemurs in the enclosure were only logged as in the box by the system for a to tal of around 6 minutes Most records of the animals entering the OSCaR were visits of under 20 seconds each and most occured in the first two days while it was still secured to the branch As a result of this there was insufficient data for calculation of BMR for the grey mouse lemur 5 5 Size Limitations
74. r after the original po sition became unsafe for the animals and the device was moved to the feeding shelf a part of the enclo sure where they were not used to using a nesting box they became far more reluctant to even investigate the device for brief periods of time The keepers were asked to occasionally place food inside the box to entice the lemurs in but it is clear from the collected data that the animals would simply retrieve this food and immediately exit the box Even after four weeks of the box being present the lemurs were not noticeably using the box any more than when it was moved and would have unfortu nately needed significantly more time to become ac customed to the box in its position on the shelf than was available 6 4 Size Limitations 6 4 1 Paraffin Wax Burner Effective BMR The effective BMR of a 10g paraffin wax burner does not represent the number of calories that are com busted by the burner rather it suggests what the BMR of an animal with the same rate of oxygen consumption would be as calculated by the OSCaR If Kleiber s law as described in section 2 3 is assumed to be accurate then using equation 2 we find that the effective BMR of the 10g paraffin wax burner 13 1 5 kcal day is approximately equal to the BMR that would be calculated for an animal of mass 0 12kg The mass of the Grey Mouse Lemur ranges from 58 67g 6l This suggests that two mouse lemurs can well be modelled by a singl
75. r may be in a wider context in terms of animal husbandry and conservation Dr Schwitzer outlined three distinct groups of specialists who may be interested in a calorimeter the first of which being other zoological gestablish ments He advised however that there may not get a huge response from his colleagues most zoos are conservative organizations and tend not to be overly receptive to new ideas Dr Schwitzer explained that a new product is often first showcased following a paper being published at an international zoology 16 conference but it can take over a decade and re quire endorsement from a respected member of the scientific community such as him before it will be integrated into zoos on any significant scale In ad dition BZG is a rare organisation in that they have very strong connections to both the University of Bristol and the University of the West of England and is particularly research led Most zoos are not specifically interested in optimising the nutrition of the animals they house unlike in livestock husbandry there is no cost or quality benefit to tailoring nutrition plans as animals are primarily there for decoration Nonetheless there is a distinct group of zoos that specialize in nutrition and or research that would be worth contacting Dr Schwitzer also suggested targeting Ameri can universities Zoos in the US tend to outsource nutrition plans to universities who have specialised animal nut
76. r the more accurate the BMR reading The mass is the mass per animal in the box and is displayed in grams and the temperature T is displayed in degrees Celsius 10 User Guide UoB GIP 2012 13 4 Troubleshooting This section of the guide highlights common issues users may encounter and offer simple solutions The device is able to self identify a limited number of issues which present themselves as error codes within the saved data on the storage device There are also a few other issues which can be easily diagnosed 4 0 No Data Ifthe device has not read any data there could be a variety of problems If the data file reads Setup and no additional information text then the device has been powered and successfully initiated but no animals have been present in the box 4 0 1 No Setup Ifthe data file does not read setup on the first line then the device has had no power or been unable to establish a connection to the micro SD card First put the micro SD card in the device and power it on making sure the Arduino LEDs are visibly on Wait around 30 seconds before turning it off again Remove the micro SD card and open the data file If the device still does not read Setup on the top line the micro SD card or the Arduino shield may be faulty Ifit does now read Setup then the device was either incorrectly powered or the micro SD card was not inserted into the Ethernet shield properly 4 0 2 Multiple Setups
77. rature and humidity expected in Madagascar and most importantly be non intrusive The theoretical size limitations of the device were considered and several other species were identified as potential candidates to which this method of open system calorimetry respirometry could be applied 17 Appendices Appendix I Circuit Diagram Circuit diagram showing the electronic layout of components that make the instrument oo 02 Sensor wmo 3 1 2 02 Sensor Arduino Pins Jo LL 470 HN LED1 Load Ce e i Appendix II Complete Arduino Code include lt Arduino h gt include lt SD h gt include lt SoftwareSerial h gt define define define define rxPininside 2 txPininside 3 rxPinoutside 5 txPinoutside 6 SoftwareSerial mySerialin rxPininside txPininside SoftwareSerial mySerialout rxPinoutside txPinoutside The two values below MUST be individualised for a nest box iii const double Area 0 002206 Area of entrance in metres squared const double Length 0 036 entrance length in metres const double interval 10 time interval between readings long t int sensor0 AO int sensorl Al int lemnum 0 numnow 0 initial 1 state 1 i 0 int array 2 const int chipSelect 4 chipSelect pin needed for interface with SD card File dataFile double mass masssum double interceptOffset 0
78. reators OSCaR BMR Instrumentation Box Table of Contents Iitroductionms a sy s ette inte ae aa Lade t su AA bo ce cotes 1 A 1 PA E dd Nd NN 2 2 1 If the initial setup has been completed I cerrar raras 2 2 2 Adapting an animal nest box for the device a 2 2 2 1 Measurement of the neW DOX serenade 3 Bete PMA QING u E E E E A A 4 2 29 MENTOR 6 S Retrievitie DAN ee aco abo dd ed ede ane baeten enten Hadad aderen 9 A ennn oenen enen eene ede ee ee 10 20 TET LS ING A A d ade tat 10 AO TINO SC EE 10 2 077 Multiple A Ie ect 10 4 1 Error 1 Animal Counter Error as 11 4 2 Error 2 Negative Animal Count I es 11 4 3 Error 3 and Error 4 Oxygen Sensor Not Working u 11 AA A A Supa u LE 12 SAA COGO neis du ed d eee M E 12 5 2 Appendix II Components list ote teo est 26 User Guide UoB GIP 2012 13 1 Introduction The OSCaR has been designed to measure the Basal Metabolic Rate of an animal or animals in a non invasive manner and return the data to the user in the simplest possible way Even with its simple design there are still some pitfalls to be wary of and information that needs to be provided in order to facilitate any duplication of or changes to be made to the equipment A short description of the reasoning and science behind the device is provided in section 1 1 below but is not necessary knowledge for the operation of the instrument box and can be skipped with no loss to
79. rint tT dataFile print tempout if E 0 Serial println dataFile println else if E 1 Serial println tError 1 dataFile println tError 1 else if E 2 Animal counter error Animal counter error gt Serial println tError 2 Negative animal count dataFile println VtError 2 Negative animal count dataFile close numnow lemnum if the file doesn t open pop up an error else Serial println error opening lemur txt double Percentage Here begins the list of functions for various data capture h 0 j 0 mySerialin begin 9600 mySerialin write r n delay 13 while mySerialin available gt 0 c h mySerialin read h 1 mySerialout begin 9600 mySerialout write r n delay 13 while mySerialout available gt 0 d j mySerialout read j 1 c2 0 c 2 d2 0 d 2 cuts the letter off the data returned by the c2 1 c 3 d2 1 2d 3 sensor so it can be converted to a double c2 2 c 4 42 2 a 4 c2 3 c 5 a2 a d 5 c2 4J c 6 a2 4 d 6 c2 5 c 7 d2 5 d 7 percentin atof c2 conversion from string to double percentout atof d2 return percentin percentout double Temp h 0 j 0 mySerialin begin 9600 mySerialin write T r n delay 7 while mySerialin available gt 0 c h mySerialin read h 1 xi
80. rition departments He noted that broadly speaking European zoos feed animals a fresh diet that includes a wide variety of fruit and vegetables whilst animals in American zoos are mainly fed in the form of pellets It would be interesting to compare the BMR of captive lemurs raised on very different diets Finally he suggested that feed manufacturers may have a use for the product There are many nutrition problems that are specific to lemurs such as obesity and iron storage disease which are potentially fatal Lemurs should not be fed the same diet as other pri mates and require a nutrition plan high in fibre low in iron and with readily available carbohydrate As a nutrition and lemur specialist other zoos frequently ask Dr Schwitzer what they should feed their captive lemurs and he imagines there would be a large mar ket for a lemur specific range of feed He highlighted Mazuri supplier to BZG as a company who do not currently have a lemur specific pellet available They may be interested in using a calorimeter to develop a new range of feed 6 6 2 Survey Primarily this investigation involved an online sur vey sent to various establishments who we identified as potential users of such a device The survey also aimed to find out if these establishments already had devices for measuring BMR whether using open or closed calorimetry and any issues they had with the device they had and the expected cost of such a de vice A s
81. sent to them may have not been willing to spare time from their busy schedules to fill in the survey at all whereas representatives interested have taken the time to express this interest The full set of questions and all responses have been included in the appendix VIII 6 6 4 Conclusion From the responses to this survey it can be assumed that their is an interest and a market for an open sys tem metabolic calorimeter both in zoological and aca demic establishments Cost would be the main issue but this device is much cheaper to produce than most respondents would expect to pay indicating that this device could be a viable option for many establish ments and therefore could be a marketable device 7 Conclusion The project was successful in creating a device ca pable of providing a non intrusive and indirect mea surement of the BMR of the Grey mouse lemur using an open system calorimetry respirometer Unfortu nately no value of BMR for a lemur was obtained as the lemurs did not use the nest box for periods of time long enough to retrieve useful data Investiga tion into the BMR of the Djungarian hamster yielded a result of 22 4 2 8 kcal day which is close to the expected value for this species and was evidence that the device is a viable method of measuring BMR The project achieved the objectives outlined by BZG which were that the calorimeter should be portable inexpensive able to withstand the extremes of tempe
82. study and possible future reintroduction projects The knowledge gained from metabolic research at the university will allow zookeepers a much greater insight into the physiology and nutritional needs of the animals they house and in turn will also inform the conservation measures of lemurs in the wild The measurement device that that was commis sioned was to be used both in the zoo and in the wild and so must be able to withstand the extremes in temperature and humidity expected in Madagas car The device was to be portable and cost effective but most importantly nonintrusive The protection of wildlife is of paramount importance to BZG which is why work was carried out in accordance with the zoo s mission statement Bristol Zoo Gardens maintains and de fends biodiversity through breeding en dangered species conserving threatened species and habitats and promoting a wider understanding of the natural world 2 Detailed Background 2 1 Basal Metabolic Rate In theory a metabolic rate can be calculated from a balance sheet of energy gain and loss as detailed in formula 1H rate of energy intake rate of energy expenditure metabolic rate 1 The basal metabolic rate BMR of an animal is the energy it requires just to maintain vital organs it is the minimum cost of living The BMR of an animal is defined as the energy expenditure of a non growing individual per unit time when at complete rest in a post
83. tabolic rate of the Grey mouse lemur The device should be free standing log data and withstand environmental conditions for use in the field in Madagascar The device may be tested using the Grey mouse lemurs at BZG Prof Barham added that the project could be extended to adapt the instrumentation for different types of animals and calculate the theoretical limit to the size of animal suitable for experimentation with the method Action Members acknowledged 2 Accessing Past Apparatus Prof Barham proposed that Tom Kennedy be contacted in order to obtain and examine equipment used by previous students with similar brief Action Sarah Buxton 3 Access to Zoo Resources Dr Schwitzer proposed access to zoo with research passes and use of zoo literature Action Deferred until required 4 Zoo Project Proposal Dr Schwitzer requested completion of a BZG project proposal form Action Sarah Buxton El e Ke University of ES BRISTOL School of Physics Bristol Zoo Gardens Group Industrial Project Meeting Access to Zoo and Resources Date 12 01 2013 Location Bristol Zoo Gardens Chairperson Nicholas Pestell Secretary Fergus Kidd In Attendance Dr Sue Dow Research Officer Bristol Zoo Gardens Sarah Buxton Communications Officer Charles Hannigan Treasurer Apologies N A 1 Research Passes Dr Sue Dow organised for project members to be provided with research passes to gain access to the zoo at any time Action Memb
84. the BMR of the animal s in a nesting box the number of animals and their mass is also given User Guide UoB GIP 2012 13 2 Setup The electronics and accompanying computer code have been designed to be as easy to set up as possible though there are several steps needed to get everything up and running 2 1 If the initial set up has been completed If everything above has been completed but you disconnect the device from its power source or equivalently the batteries run out then pressing the red reset button once power has been restored will start the device running again with the results then showing multiple instances of a setup this is completely normal 2 2 Adapting an animal nest box for the device When looking to change the animal and therefore nest box that the device will be measuring there are several factors to take into account Attaching the instrumentation box means first altering the nest box it will be attached to the OSCaR has several holes through which instruments protrude or instrument wiring runs and appropriate holes must also be made in the adapted nest box One hole should be made for the internal oxygen sensor which has a bore of 22mm one at the bottom for the scale wiring and another for the light gate wiring There should also be three small holes made for the bolts that attach OSCaR to the nest box The approximate positions and sizes of these holes on a nest box are shown in figure 1 but accurate
85. time it may prove useful to investigate power ing the device from the mains This can simply be achieved with a cheap commercially available adapter which plugs directly into the Arduino The investigation into size limitations suggests that the technique conceived through this project is applicable to many other species It is proposed that further exploration into using this technique with other specific animals is a fitting extension to the project It would be practical for use with small mammals of similar size to the Grey mouse lemur such as the Kangaroo rat and the Kowari The tech nique may also be appropriate for use on many differ ent species of birds in particular the Inca Tern the Lilacine Amazon parrot and the Red Vented Cocka too The study also suggests that the technique may be practical for use with significantly larger mammals and birds specifically the Red panda and the African Penguin 6 6 Market Research 6 6 1 Motivation The motivation behind building the calorimeter was as an industrial project which prompted considera tion of the commercial viability of the OSCaR Once a working device was created a market research survey was conducted to find out whether the calorimeter would be a viable method of measuring BMR for researchers and gamekeepers at other zoological es tablishments across the UK Other potential uses of the OSCaR were investigated to gain a better un derstanding of how useful the calorimete
86. ubsequent set of questions included details questioning what the device may be used for and what species each establishment would have specific inter est in 6 6 3 Results An encouraging 25 of establishments invited to par take in the survey responded Zoological institutions with research departments were specifically targeted of which 100 of the replies indicated that they would have use for such a device for various purposes for a range of species The majority of species indications were for small nesting mammals and birds Inter estingly two institutions expressed direct interest in measuring the metabolic rates of large cats in dens with such a technique None of the zoological institutions that responded already had a device capable of measuring the BMR of an animal and many indicated that tight budgets may prevent the purchase of such a device Most institutions expected such a device to cost thousands of pounds but all indicated they would not buy such a device at this expected cost Only one academic institution responded and gave limited information about the closed system calorime ters they currently had in use They also indicated that they would still be interested in an open system device While it is excellent that 100 of the replies in dicated a use for the device it is important to con sider a bias where representatives of institutions not immediately interested in the idea as outlined in the letter
87. vice versa this means any blocking even slight of the LED by an animal sets off the trig ger The gates were positioned in a cross shape to prevent any blind spots in the entrance that the an imals could inadvertently slip through and said cross was orientated such that no sensor or LED was posi tioned directly at the bottom of the entrance where it could easily become blocked by debris 3 1 7 Scales Finding a set of commercial scales that was small enough to fit into the base of the nest box and then integrating them in with the Arduino electronics was deemed to be unnecessarily complex instead it was decided to extract essential parts from commercially available scales and assemble a new set though this still necessitated an increase in the height of the nest box to comfortably accomodate the mechanism The specific part needed was a load cell which can be found in most kitchen scales A load cell is essentially a Wheatstone bridge made up of strain gauges which are fixed to a flexible metal bar two strain gauges are fixed to the top of the bar and two to the bottom When it is fixed at one end and a load is applied at the other the bar bends slightly this changes the resistance of the strain gauges de pending on their position and creates a voltage across the Wheatstone bridge that varies linearly with load applied The voltage that occurred across the bridge was on the order of microvolts which is too small for
88. was ef ficient while 20MIPS was definitely in excess of the speed needed to run this project 3 1 4 Data Storage Arduino electronics are designed so that they can be used with a wide variety of add ons called shields produced both by Arduino and also by third party manufacturers Among these there is the Arduino Ethernet Shield which primarily allows the controller to communicate via an Ethernet cable however it is the secondary function of this shield its SD card interface that made it attractive for this project The Ethernet Shield has a micro SD port built in to it which allows data to be passed from the Ar duino onto a micro SD card which is a high density storage medium As mentioned in section 2 5 in pre vious years remote storage has been an issue but by using the shieldl17 what would otherwise be a hard ware and software problem became a matter of just software i e programming the Arduino to write to the SD card 3 1 5 Oxygen Sensors Previous iterations of this project have used the EC410 analogue electrochemical oxygen sensor but have consistently had problems with calibration This particular sensor also needs an accompanying am plifying circuit further complicating matters The problems with the EC410 galvanised a search for a better sensor which was found in the form of a Lu minOx Oxygen Sensor which is cheaper has better resolution a longer expected lifetime and contains no hazardous materials
89. xygen consumed only varies by around 10 between them being 5 kcal It 4 8 kcal I and 4 5 kcal I for carbohydrates fats and proteins respectivelyl l Schmidt Nielsen states that it is cus tomary to use an average value of 4 8kcal I O2 as a measure of metabolic rate The largest error resulting from the use of this mean figure would be 6 5l In practice a balanced diet is likely to mean this error is smaller than the maximum and perhaps insignifi cant in the face of larger experimental uncertainties Using the average value stated by Schmidt Nielsen we arrive at the following equation describing the relationship between BMR in kcal st and oxygen consumption BMR 2e x 4 8 4 The amount of energy released per litre of car bon dioxide produced varies more greatly than that of oxygen consumed For instance the difference between the conversion rates across three predomi nant food groups causes a maximum discrepancy of 34 9 contrasted with 6 for oxygen consumption This makes oxygen consumption a far more suitable method for measuring BMR Two specific types of respirometry exist In closed system respirometry the animal is confined to a sealed chamber which is maintained at a constant pressure A steady controlled supply of oxygen is entered into the system which is an indication of the oxygen con sumption of the animal 9l In contrast in open system respirometry gas is able to flow in and out of the chamber The d

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