NZ511032A - Animal temperature sensing device including an ear tag having an animal and an ambient temperature sensors - Google Patents

Abstract

Disclosed is an animal temperature sensing device including an ear tag having an attachment portion to attach the ear tag to the animal, an animal temperature sensor disposed on/in the attachment portion to be in close contact with the animal during use, wherein the ear tag includes an ambient temperature sensor, wherein the ear tag includes a comparison means to compare the temperature between the animal temperature measured by the animal temperature sensor and the ambient temperature measured by the ambient temperature sensor and wherein the ear tag includes an indicator means responsive to the comparison means.

Description

511032 ANIMAL TEMPERATURE SENSING DEVICE FIELD OF THE INVENTION The present invention relates to animal temperature sensing device which may be used to predict meat pH and stress levels, as well as meat quality in an animal. These devices are also useful in monitoring the physiological state of an animal.

BACKGROUND ART Livestock stress has long been recognised as having a major impact on the postmortem quality of the animal tissue.12'3,4'5 The present applicant has found that in all animals subjected to stress, body temperature changes produce either an increase or decrease in skin heat loss. Changes in body temperature both up and down from the homeostatic norm are energetic that is energy must be used to re-establish norm by pulling body temperature up or lowering it (heat production or heat loss). Often these adjustments are quick and not reflected in deep body temperatures. They are, however, reflected in skin and surface temperatures and peripheral blood flow mechanisms ie. in the outer body. High energy expenditure can be made with little change seen in core temperatures. Falls in body/ skin temperature are as (if not more) energetically demanding than rises.

In terms of stress measurement both a fall, or rise, in skin/body temperature can be an important indicator of stress, and such changes can be important both acutely and chronically (i.e. a number of changes) over time. In terms of predicting meat quality, cumulative stress, or more specifically cumulative energy expenditure, is more important than acute stress (other than extreme acute stress). A cumulative measure of skin/body temperature changes (both up and down) can provide an index over time of the amount of energy spent by the animal. The more energy spent by the animal over a 24 hour period prior to its slaughter .the more likely that O'ot i\|.z. 2 3 FE3 2005 the meat will be of poor quality if the animal is not allowed an additional period to replenish its energy stores via eating.

As stress has energetic consequences it can influence production return and can have implications for animal welfare. A simple tool for measuring and offering 5 quality control on these would be useful.

Animals that have meat ultimate pH levels in an acceptable range (pH 5.5 - 5.8) show a weak correlation between body temperature at slaughter and the actual meat pH. This correlation is greater if changes in body temperature are integrated over time, preferably for at least 12 hours prior to slaughter. A convenient way to do this 10 is to use a cumulative variance around an averaged body temperature for an individual animal. Higher cumulative variances in temperature predict higher pH meat, a measure that relates to the amount of glycogen residing in the meat. Based on the applicant's findings of the correlation between pH, temperature and stress, it is proposed that animal sensor devices may be produced to monitor body 15 temperature, and its variance, as a measure of an animal's stress level and as a predictor of meat quality.

Animal temperature sensors are known in the art. For example, in US 3,781,837 and US 4,865,044, tympanic temperature sensors are employed. In US 4,854,328, a temperature sensor device is implanted at the base of an animal's skull. An ear tag 20 component is provided which incorporates a unit for receiving signals from the implanted sensor, and indicating means responsive to the generated signal. In the case of US 4,865,044, an ear tag is employed to contain the bulk of the temperature sensor circuitry, at a position remote from the tympanic animal temperature sensor.

The use of tympanic and surgically implanted sensor devices is usually 25 contraindicated because of the high invasive load on the animal. Further, dislodgement problems are also encountered with tympanic sensors. Where implanted devices are used, incisions can easily become infected and the implantation procedure is more difficult to carry out. 2 3 m 2m Accordingly, it is an object of at least a preferred embodiment of this invention to provide a temperature sensing device which overcomes some of these disadvantages, or again at least provides the public with a useful choice.

In a first aspect the present invention consists in an animal temperature sensing 5 device including: an ear tag having an attachment portion to attach the ear tag to said animal, an animal temperature sensor disposed on/in said attachment portion to be in close contact with the animal during use, wherein said ear tag includes an ambient temperature sensor, wherein the said ear tag includes a comparison means to compare the temperature between the animal temperature measured by the animal temperature sensor and the ambient temperature measured by the ambient temperature sensor, and wherein the ear tag includes an indicator means responsive to the comparison means.

Preferably said attachment means includes a shaft insertable through the ear of an animal and wherein said animal temperature sensor is disposed on/in said shaft.

Preferably said sensor is disposed in said shaft.

Preferably said sensor is provided on said shaft.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents 25 are deemed to be incorporated herein as if individually set forth. fir r*<v;*3ity OiilOt? q{ hl.Z. 2 3 FEB 2005 The invention consists in the foregoing and also envisages constructions of which the following give examples.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described with reference to the accompanying 5 drawings in which: Figure 1 is a diagrammatic view of an embodiment of a temperature sensing device of the present invention from the inward facing or "animal" side.

Figure 2 is a side view of a temperature sensing device of the present invention.

Figure 3 is a diagrammatic view of an embodiment of a temperature sensing device 10 of the present invention from the outward facing or "environment" side.

Figure 4 is a graph plotting the ultimate pH of meat with temperature variance from Example 1.

Figure 5 is a graph plotting the results of Example 2, correlating variance in skin temperature around a mean value over 24 hours in sheep with ultimate pH.

Figure 6 is a graph plotting the results of Example 3 showing the mean and SD rectal temperatures of adult sheep with similar levels of infection taken at the same time each day at the same ambient temperature. The ear skin temperatures are plotted against corresponding the rectal temperatures.

Figure 7 is a circuit diagram of a circuit which may be implemented in a 20 temperature sensing device which is slightly modified from the device shown in Figures 1 to 3.

Figure 8 is a graph plotting temperature readings and the output of a preferred algorithm in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION C,VuM of N.Z. 2 3 FEB 2005 i Li V L As summarised above, the present invention is based upon the applicant's unexpected finding of the correlation between stress, body temperature and variance over time of body temperature, pH and ultimately meat quality in livestock. This finding has important consequences for the agriculture industry generally and the 5 primary meat industry in particular. By identifying stressed animals prior to slaughter, appropriate management techniques can be used to reduce the animals' stress level. This will ensure a higher quality meat product after slaughter.

The applicant's findings also have broader application to methods of predicting or measuring pH levels based on the pH/temperature correlation.

Animal body temperature may be measured using a broad range of temperature sensors including tympanic, rectal, colonic, and skin sensors. Sensors ingested or inserted in bodily canals are not widely used due to the difficulty of inserting them, and because they are easily dislodged or expelled by an animal. Preferably, a skin temperature measurement is taken to avoid these invasive and less desirable 15 alternative techniques. Conveniently, temperature may be measured using a temperature sensing device of the present invention discussed below. However, with temperature measurements from the skin as opposed to the body core, the ambient environmental temperature must be taken into account. The slope of prediction between variance in temperature and ultimate pH of meat shows 20 consistency with temperature change. However, it shifts to the right, or to the left, depending upon the environmental conditions including temperature and solar radiation.

Measures of animal and ambient air temperature or measurements corresponding thereto, and usefully over a predetermined time period are required. On the farm, 25 any time interval, regular or irregular, desired may be selected. Continual on-line monitoring not limited to a specific time period is contemplated. Alternatively, monitoring for selected time periods of hours, days, weeks or even months is feasible.

It i of W.7. 2 3 FEB ass In the slaughtering context, the correlation between body temperature at slaughter and pH levels of meat are stronger if the measures are integrated for an extended period, which may be up to 2-5 days, but is preferably between 3-36 hrs, more preferably 8-24 hrs and most preferably at least 12-14 hours prior to slaughter.

Within the monitoring period it is preferred that measurements be taken at regular intervals such as hourly, half hourly, every quarter hour, every ten minutes or the like. The preferred regime is no more frequent than every ten minutes.

The applicants have found that skin/body temperature may reflect metabolic activities associated with the stress response. A greater stress response is likely to 10 result in a greater metabolic activation to re-establish the homeostatic norm either through a greater generation of heat and elevation of body temperature or heat loss and a lowering of body temperature. Except in circumstances of pathophysiological heat exhaustion, dehydration or febrile responses these changes are usually shortlived in nature and small in magnitude.

Measurements of animal body-temperature made at discrete points of time during the pre slaughter period are unlikely to give a representation of the stress experienced cumulatively over the preslaughter period. A single experienced stressor is unlikely to cause meat quality problems whereas cumulative stressor exposure over a period of time, without replenishment, will do so.

Correspondingly, single point temperature measures may well coincide with either a single stressor induced peak or a trough between numerous stressor induced peaks in body temperature, either way unlikely to provide an accurate assessment. It is for this reason that measurements over a time period prior to slaughter are required.

The applicant hypothesised that the best measure of energy used, and by 25 correspondence glycogen depleted from muscles and predicted ultimate pH, would be the variation in body (or skin) temperature over time. The variation will represent both periods in which skin/body temperature has fallen and the required energy consumption to correct, and periods in which body temperature has risen, w.-i'v,;"-1 tj I i\i / 2 3 FES 2005 reflecting increased metabolism and its energy consumption and necessitating heat loss.

A measure of the temperature variation (variance) can be calculated in numerous ways. However, a simple cumulative measure using single measure sample period 5 repeated over the required time is as follows: find the arithmetic average (x) of all the pooled samples (y 1,.. .yn) where 1 = the first sample variable y and n the last in the sequence, which is also the total number of samples. x=sum(yl+y2+ ...y„)/n measure and record the variance (vl,...vn) of each sample (yl...yn) from this 10 average (x) (i.e. the difference between each sample and the average). Irrespective of whether each sample point is less or more than the average the difference will be indicated as a positive number. vl=x-yl,....vn+x-yn.

A further weighting may to be given to each variance dependent upon whether it is above or below the average. Values above the average or mean have energy 15 associated both with generation (variance) and the energy loss through heat transfer needed to return to the average. As such their variance weighting should be greater than those below the average that utilises energy only in returning to the average baseline.

These numbers are then cumulatively added to give a variance score over a 20 predetermined time period. This time period will usually need to be 12 hours or greater to provide meaningful interpretation as to glycogen depletion and energy usage as discussed above. Vc=Sum(vl+v2+....vn) The greater the cumulative score, the greater the energy usage that has occurred and correspondingly the greater the likelihood of both glycogen depletion and 25 subsequent post- slaughter poor meat quality.

To calculate the prediction of meat quality a weighting should also be given to the variance depending upon the environmental conditions. Increasing ambient Ur..;:o Oi W.7. 2 3 FES 2005 temperatures are associated with a subtractive weighting, decreasing ambient temperatures with an additive weighting. Solar radiation can also be accommodated for using this method.

The weighting for ambient temperature is approximately ± 0.2 pH unit per 3°C 5 above and below 20°C (standard weighting of zero).

Based on the applicant's determination of a correlation between temperature and pH, the cumulative effects of variation in body temperature can be manually or electronically correlated with ultimate meat pH using a standard. For example, standardised against a Mettler Toledo pH meter and standards (Mettler Toledo 10 GmbH, Steinbach). Further it could be correlated to any other measure of hydrogen ion concentration, typically using a glass electrode, but other methods including ion selective field effect transistor electrodes could be used. As the increasing pH in meat is correlated with an increase in lactate, a measure of lactate also provides suitable correlation.

The pH level measured can be used as an indicator of an animal's stress level, a pH of greater than 5.8 indicating stress.

Where an animal is found to be stressed, remedial action to lower stress levels can be taken prior to slaughter. A period of feeding should alleviate stress by replenishing glycogen in muscle tissue. This action helps prevent or eliminate post-20 slaughter meat quality problems.

The methods of the invention may be used in relation to a broad range of animals including domesticated livestock such as sheep, cattle, deer, pigs, chickens, turkeys, ducks, emus, ostriches, rodents, chinchillas and additionally rabbits, possums, goats and the like, as well as the feral counterparts of all of these. Preferred livestock for 25 analysis are sheep, cattle, deer and pigs.

As noted above, the present invention also provides a temperature sensing device depicted generally by the numeral "10" in the accompanying figures. The sensing device (10) is useful in the methods of the invention fot-measuring temperature. A 5rv. .... ^ UiH.'.}■< r..t / 2 3 FES 20C5 sensing device (10) of the invention includes a tag represented by the numeral "12". The tag (12) may comprise any of the tags known in the art which can be attached to the skin of an animal, including through the skin, folds thereof, or tissues. Examples of useful tags include ear tags, back tags and tail tags.

Ear tags are conveniently employed.

Two part ear tags are disclosed in US Patent No. 4,854,320 or three part tags of the type disclosed in US Patent No. 5,675,920 may be used. One part tags wherein an attachment portion of the tag passes over the top of, and back through the ear and tag are also feasible. Currently preferred is a two part tag as illustrated in Figure 2. 10 For example, the Tru-Test7 perma-flex ear tag (Tru-Test Limited, 241 Ti Rakau Drive, East Tamaki, Auckland, New Zealand). The tags are generally useful for domestic livestock such as sheep, cattle, deer and goats but are not limited thereto.

The tag (12) incorporates at least one attachment portion (14). The attachment portion (14) comprises any suitable attachment means known in the art including 15 any form of skin piercing. The attachment portion (14) may be selected according to the position of attachment on the animal. Suitable attachment portions may include shafts, bands, hooks insertable into or through selected animal tissues, or attachment portions adherable thereto. For example, tags could be superglued to the skin of an animal at a desired location. Preferably, the attachment portion (14) includes a shaft 20 (17) insertable through the ear of an animal. Where necessary backing member(s) (15) may be used to securely fasten the tag to the ear of the animal. The backing member (15) may include a further tag body in some cases. Alternatively, in one embodiment discussed above, the attachment portion (14) may be secured back to the tag (12).

The tag (12) incorporates at least one animal temperature sensor (20) disposed on or in the tag. The sensor (20) is disposed at any location on or in the tag (12) which ensures contact of the sensor (20) with the animal during use. In one embodiment the sensor (20) is in the vicinity of the attachment portion (14). In a preferred embodiment shown in Figure 2, the sensor (20) is provided on «r in-th© sha&^+T^-af 0—5 o: r.Z. 2 3 FE3 20C5 the attachment portion (14). The location of the sensor (20) in the shaft (17) ensures close contact of the sensor with the animal ear.

The temperature sensor (20) itself may comprise any suitable sensing means known in the art including electronic sensors or thermistors. Temperature sensors suitable 5 for use in the invention are disclosed in US 4,854,328 and US 4,865,044 at least.

As discussed above, where outer body temperature readings, such as skin temperature are used, then the ambient environmental temperature should also be measured. For example, on a hot day an animal's body temperature will rise. If not correlated with air temperature this would falsely indicate a stressed or sick animal.

Logically therefore, a more accurate assessment of an animal's body temperature can be made if the ambient air temperature is taken into account.

Accordingly, while a tag (12) without an ambient temperature sensor is contemplated, the tag (12) preferably further includes at least one ambient temperature sensing means (18) provided on the tag (12) at any position suitable for measuring ambient air temperature. Most usually, the ambient temperature sensor (18) will be disposed on or in the side of the tag (12) away from the animal, as shown in Figure 1. Temperature sensors of the type used for animal temperature measurement may also be employed for ambient temperature measurement. Such other air temperature sensors as are known in the art may also be used.

Correlation of both body and air temperature data can be performed manually by an observer. However, it is preferred that the sensing device (10) further include comparison means for correlating temperature data from both the air and body temperature sensors (18 and 20). Usually, the comparison means will be a microprocessor (22) but application specific electronics could also be implemented.

In order to resolve difficulties associated with heating of the ear tag due to solar radiation, the animal temperature sensor could instead be located some distance from the tag. This is easily done by positioning the body of the tag just inside the ear flap and the sensor just inside the ear canal. The sensor can be located on the o,^:; ■„}■ u. z11* A A fr-rv end of a flexible wire and glued to the ear. Ambient temperature effects can be minimised by covering the sensor with a small dot of foam insulating tape.

The data output of the body and/or temperature sensor means (18 and 20) may also or alternatively, be sent to remote evaluation means. This will generally require the 5 coupling of the sensor means (18 and 20) to a transmitter. Temperature data as well as animal identification data is transmitted to a remote processor such as a computer. In the case of tagged animals this will permit remote monitoring and checking to be performed, continuously if desired.

In the presently preferred embodiment, the temperature information gathered by 10 both sensors (18 and 20) is relayed to microprocessor (22). In this regard, refer to Figure 7 which illustrates the circuit diagram for a device according to a slightly modified embodiment. While changes would be required to implement this circuit in the present embodiment the principles of operation are the same. Reference is also made to US 4,854,328, US 4,865,044 and US 3,781,837 which disclose 15 circuitry which could be adapted for this use.

The microprocessor (22) is in turn in responsive communication with indicator means (16). The indicator means (16) may be selected from a broad range of currently known indicators including electronic, visual and acoustic signal generators but are not limited thereto.

In the case of an electronic indicator this may be a device programmed to give out a perceivable signal once a certain predetermined temperature is reached.

In one embodiment, the indicator means (16) may comprise a temperature responsive substance which generates a visual, electromagnetic, electrochemical, or other measurable signal when a predetermined temperature is exceeded. Visual 25 changes such as a change in colour are conveniently employed. Colour change indicators will generally comprise a substance which undergoes a change in state at a precise and predetermined temperature. o.' w f £vvJ In a further embodiment, the indicator means (16) may comprise a plurality of regions, generally less than 10 and preferably less than 5, which undergo a change of state at precise, graduated predetermined temperatures. When colour changes are employed this may usefully result in the graduated change in colour of the indicator 5 from a small portion to substantially the entire indicator. In an embodiment which progressively applies the algorithm resulting in a progressively increasing cumulative value, this progressive colour change might effectively indicate the progressively increasing cumulative value. Alternatively, the colour change might be simply representative of increasing animal temperature. Alternatives include a 10 "traffic light" indicator which, for example, changes from green, to amber, and finally to red as the threshold is exceeded. Other possibilities include opaque materials becoming transparent or translucent to reveal underlying colours as the cumulative value increases or the temperature changes.

The indicators may undergo irreversible changes, especially when continuous 15 monitoring is not contemplated.

Further visual indicator means (16) include, for example, LEDs or flashing lights. Alternatively, audible alarms may be triggered. Combinations of all such indicator means are also feasible. Also contemplated are outputs readable at remote locations. A wide range of indicator means (16) which may be employed in the invention are 20 disclosed in the following US patents: US 3,781,837, US 4,865,044, US 4,854,328 and US 5,675,920 amongst others.

Depending on the types of sensors, indicator and comparison means employed, the sensor device may require a power source. While solar powered devices are contemplated, at least one battery will usually be incorporated into the sensing 25 device (10). In the preferred embodiment depicted in Figure 1, a battery "24" is employed. A wide variety of batteries (24) are currently available and suitable for use in the ear tag (12).

Where batteries (24) are employed as a power source it is important to identify when a battery (24) has malfunctioned or expired. An indicator showing when the 0 1 FFR power source has failed would therefore be useful. An appropriate indicator is identified by the numeral "26" in Figure 1. As with the sensing means, useful indicators include electronic, audio and visual signals as discussed above. For example, when the battery has failed an audible signal could be emitted, driven by a 5 small backup power source. Preferably however, the signal is a visual colour change signal, or extinction of an "OK" LED signal. The colour change may be signalled as an alternative to the temperature colour change signal, or in addition to it provided that the colour changes are distinctive.

The tag (12) may further incorporate communication means. The communication 10 may comprise the export of data and/or for the import of energy. Accordingly, uni-and bi- directional communication means are contemplated. Suitable communication means are identified in the US patents referenced above. They include at least one transmitter and/or antenna but are not limited thereto. In a preferred embodiment of the present invention an antenna (28) is included in the tag 15 (12). The antenna (28) preferably allows bi-directional data communication with the tag (12).

In one use, the antenna (28) provides a means of recharging the battery (24) by use of electromagnetic radiation or an externally applied radio frequency field. In a further use, the antenna (28) permits export of data for logging purposes. 20 Communication may be to remote data logging means to facilitate off-site monitoring of animals. Exported data signals may also provide information relating to the identification number of the animal.

It is also customary for tags (12) to include animal identification means. In a simple form this may comprise a unique visual identification means such as a symbol, 25 colour or pattern. Preferably, the visual ID comprises an alphamerical number (30) as shown in Figure 3. Alternate identification means include electronic identifications, or electronically readable signals which uniquely identify a given animal. Any such electronic signals which are known in the art may be used. One embodiment preferred is the inclusion of a barcode (32) on the tag (12) as shown in Ui 'I pr?> Figure 3. This facilitates scanning of the tag (12) and correlation of data with preexisting information for the uniquely identified animal. Specific identification systems can also assist in discouraging theft of stock.

The electronic componentry of the ear tag (12) comprising any of all of the antenna 5 (28), battery (24), battery indicator (26) and microprocessor (22) may be provided on or in the tag (12) conveniently on a circuit board (34). Preferably, the componentry is provided within the tag (12) to prevent damage. This may be achieved by covering the componentry once fixed on the tag (12). The cover may be permanently fixed in place or can be releasable. A releasable cover would allow for 10 battery replacement. If the cover is fixed, this may be achieved by gluing, plastic welding or other known fastening means.

Conveniently, the tag (12) is a one piece moulded body.

In a preferred form the tag (12) comprises an integrally moulded body with the componentry sealed therein.

In use, the temperature sensors (18 and 20) of the ear tag (12) will collect temperature data which is communicated to the microprocessor (22) to perform the necessary cumulative algorithms discussed above.

If the outcome of the calculation is a temperature threshold value that indicates a pH of poor quality (greater than 6.2) then a power surge is directed to the indicator to 20 cause an electronic, visual or audible change. The livestock owner or manager can then take steps to reduce the stress level in the animal through appropriate feeding regimes.

High temperature readings may also indicate infected or otherwise unhealthy animals. For pathophysiological measurement either a spike or chronic rise in body 25 temperature can be an important diagnostic tool of disease while longer term tracking can show whether therapeutic treatment of the disease is effective. The tags can therefore serve the dual purpose of signalling the state of health of the animal apart from stress responses. In related applications, the tags can be used in sr.: : -;;ly 2 3 F13 2&03 monitoring the status of other processes in animals which at some point are characterised by temperature changes. An example of this is measurement of hormone changes or cycles such as oestrous in an animal.

The useable lifetime of the tag is approximately one month. The lifespan of the tag 5 can be extended through the incorporation of a battery (24) able to be recharged by electromagnetic radiation or radio frequency in the field. Accordingly, both disposable single measure tags (12) and reusable tags (12) are contemplated herein. Disposable tags (12) may be particularly appropriate for short term use in the pre-slaughter period. Custom electronics could greatly increase this lifetime. Once tag 10 identification of a problem occurred, an electronic ID associated with the tag could activate automatic drafting of the animal from a group for remedial action.

Figure 7 is a circuit diagram of a circuit (40) appropriate for use in a tag such as that illustrated in Figures 1 to 3, except without the antenna (28).

At the heart of the circuit is microprocessor (42) which receives imputs from ear 15 temperature sensor TH2 and ambient temperature sensor TH1. The microprocessor (42) implements an algorithm which cumulatively takes account of temperature variations in an animal over time. Simple algorithms integrating variations from a mean body temperature over time have been described above. Also described below is a more sophisticated algorithm which may be implemented by microprocessor 20 (42). As an additional input to the microprocessor (42), there is provided a clock (44) which controls the sampling interval at which the microprocessor (42) receives temperature readings from thermisters TH1 and TH2.

The circuit (40) is driven by battery (46) which provides power to the circuit for up to six weeks. A lamp 48 such as LED D1 may flash at intermittent intervals, say 25 every 5 to 10 seconds, to indicate that the circuit is operating. The LED D1 may also be used to provide an indication when the output of the algorithm is such as to exceed a predetermined threshold. In that case, the LED may flash frequently, say every 1 second. This will attract the attendant's attention so that the stressed r Gi L i (LtwJ animals will not be put to immediate slaughter but instead rested and revived as required.

The circuit (40) also includes an optional memory unit (50) which can store up to 4,000 temperature measurements. This will be implemented if the tag is to be used as a diagnostic tool. The data stored in the memory unit (50) may be uploaded via the optional interface (52).

A more sophisticated algorithm for obtaining a cumulative measure of temperature variations in an animal will now be described.

Variable definitions: Let tear the instantaneous ear temperature Let tambient be the instantaneous ambient air temperature d is the difference between ear and ambient temperatures fast is the fast-response filter element slow is the slow response filter element v is the integral of the difference between the two filter elements cj is the time constant of the fast filter. The time constants are selected according to sampling interval time and threshold detection level.

C2 is the time constant of the slow filter Time constants are such that ci>c2, 0<cj<1, 0>c2<l n is the count for the sampling time interval Initialise: n—1 do ~tear~lambient fast0=d0 sloWg—do At each sampling time interval: dn tear ~ tambient fastn = (1-Ci) *fast„-i + Ci*dn sl0Wn = (I-C2) *SloWn + C2*dn v„ = vn.]+ (fast„-slown).

The microprocessor is programmed to repeat the algorithm regularly at each sampling interval until a predetermined time period has elapsed. If at any time during this predetermined time period v„ exceeds a predetermined threshold then the animal is taken to be stressed and lamp (48) of circuit (40) will flash frequently to 10 provide appropriate indication to the attendant. The timer will reset and remain at 0 until v falls below the threshold, at which point the timer will start counting for a predetermined animal withholding period, the timer will again be set to zero. In this way it is ensured that the animal effectively recovers from stress, prior to slaughter.

If, at the elapse of the predetermined time period v„ is less than the threshold then 15 the animal is taken to be within acceptable cumulative stress limits. The lamp (48) may provide an indication that the threshold has not been exceeded.

In the above described algorithm, the entire history of temperature readings is not required, only the most recent reading. Thus, the algorithm requires only three storage locations to be preserved between time steps.

The use of the filter elements removes any dependence on absolute reference temperatures and the need to calibrate the temperature sensors. The filter elements detect trends rather than absolute temperature values.

The filter elements are more resistant to the effects of measurement noise than simple threshold detection.

Figure 8 illustrates an example for the particular algorithm described above. Note that the threshold detection is immune to base line shifts or small spikes in the data.

Instead, a long consistent temperature rise is required for detection. The algorithm thus effectively models the rise in body temperature due to stress.

Non-limiting examples illustrating the invention will now be provided.

EXAMPLE 1 Data were obtained in the following manner: Three groups of twenty prime bulls (18 months of age) were exposed to periods of stressful handling during a 24 hour period lead up period to slaughter.

During this time skin temperature from the ear of each individual animals was measured every 10 minutes. From this an average was calculated and the 10 cumulative variance measured by adding each individual measure difference from the average.

Cumulative variances were then plotted against individual ultimate pH values obtained post-slaughter from meat. Variance values against a set ultimate pH value are presented as an average and standard deviation.

Each group of animals was exposed to a different controlled ambient temperature of 16, 20 or 24 degrees Celsius for the trial period.

In each case the correlation coefficient r2 was greater than 0.90 for variance in temperature predicting ultimate pH of meat.

Figure 4 presents data for the relationship between variance in temperature and 20 ultimate pH of the meat. Note that below a pH of 6.0 no clear relationship exists. As depicted, variance in body temperature predicts only a pH above 6.0.

For ultimate pH prediction an equation can be calculated to provide an algorithm combining the cumulated variance and the environment temperature.

EXAMPLE 2 0 ') fTO £. 3 I i.O -3 Adult sheep were subjected to various stressors including rounding up, lairage and transport in the 24 hours prior to slaughter. Ear skin measurements were made during this time, every 15 minutes. For each animal, measurements were averaged over the 24 hours and then for each measured point a variance from mean score was given using degrees Celsius above or below the mean.

The greatest total individual variance was ranked numerically as 10 and the others normalised as a dividend of this. These variances were then correlated with the ultimate pH obtained from the meat of the slaughtered animals. The results are shown in Figure 5 which shows relationship of variance in skin temperature around a mean value over 24 hours in sheep correlated against their ultimate pH. The correlation coefficient is displayed. This data suggests that in sheep, as for cattle, measurement of variation in skin or body temperature over a period prior to slaughter can predict the ultimate meat quality.

EXAMPLE 3 A group (14) of adult sheep being monitored developed respiratory and parasitic infections. Monitored ear skin temperatures showed good correlation (correlation coefficient of 0.81) with rectal temperatures in terms of fever peaks and return to normal body temperatures with treatment.

The data plotted in Figure 6 supports the notion that ear skin or ear canal temperature can be used to measure pathophysiological states that have accompanying febrile symptoms and recovery from these states.

It will be appreciated that the above description is provided by way of example only and that variations in both the materials and techniques used which are known to those persons skilled in the art are contemplated.

REFERENCES 1 Cook, C.J. and Devine C.E. (1990) From farm paddock to slaughter floor: a conundrum of biochemical and physiological effects that influence meat quality. AGMARDT Beef Industry Research Development Conference. NZMPB. 2 Purchas, R.W. (1990) An assessment of the role of pH differences in determining the relative tenderness of meat from bulls and steers. Meat Sciences 27, 129-140. 3 Watanabe, A., Daly, C.C. and Devine C.E. (1995) The effects of ultimate pH of meat on the tenderness changes during ageing. Meat Science 42,67-78. 4 Jacobson, L.H. and Cook, C.J. (1997) The effect of pre-transport cattle management on stress, metabolism and carcass weight of bulls. In: Proceedings of the 43rd International Congress on Meat Science and Technology. Auckland, NZ, pp3 02-303.

Jacobson, L.H., Cook, C.J., Hodgetts, B.V. and Dean, J.M. The effect of pre-transport on on-farm holding and supplementary feeding, on welfare and meat characteristics of bulls subsequently transported for slaughter. September 1997 (Funding Milestone, MRDC).

A Devine C.E. and Chrystall, B.B, (1992) Meat Science, in encyclopedia of Food Science and Technology, ed Hui, Y.H., Wileylnterscience, John Wiley and Sons, Inc., New York 17081723.

B Devine C.E. and Chrystall, B.B. (1989) High ultimate pH in sheep in Darkcutting in cattle and sheep. Proceedings of an Australian Workshop. Pp 5565 Ed. S.U. Fabiansson, W.R. Shorthose and R.D. Warner AMLRDC, Sydney Australia.

Devine C.D. Graafhuis, A.E. Muir, P.D. and Chrystall, B.B. (1994) The effect of growth rate and ultimate pH on meat quality of lambs. Meat Sci. 36 143-150 All US references cited in the text of this specification are incorporated herein by reference. 0 10

Claims (4)

CLAIMS:

1. An animal temperature sensing device including: an ear tag having an attachment portion to attach the ear tag to said animal, an animal temperature sensor disposed on/in said attachment portion to be in close contact with the animal during use, wherein said ear tag includes an ambient temperature sensor, wherein said ear tag includes a comparison means to compare the temperature between the animal temperature measured by the animal temperature sensor and the ambient temperature measured by the ambient temperature sensor and wherein the ear tag includes an indicator means responsive to the comparison means.

2. An animal temperature sensing device as claimed in claim 1 wherein attachment means includes a shaft insertable through the ear of an animal and wherein said animal temperature sensor is disposed on/in said shaft.

3. An animal temperature sensing device as claimed in claim 2 wherein said sensor is disposed in said shaft.

4. An animal temperature sensing device as claimed in claim 2 wherein said sensor is provided on said shaft. DATED THIS <23^() DAY OF 2o0S ENn Of CIA/MS