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What is IRT?

IRT is the measurement of radiated electromagnetic energy. Electromagnetic radiation can be described as a stream of photons, which are particles that have no mass, each travelling in a wave-like pattern and moving at the speed of light. The photons with the highest energy correspond to the shortest wavelengths. In the electromagnetic spectrum, broad range infrared radiation wavelengths (3-12 micrometers) are longer than visible light and in animals, 40-60% of heat loss is within this range. Small changes in temperature may result in substantial amounts of emitted photons (or radiated energy) that can be detected very sensitively using IRT.

Why use IRT?

The Past

In the past dairy cows were milked and known individually.

The Present

Herd sizes have increased and it has also become more difficult to recruit experienced staff with good animal knowledge and husbandry skills. In NZ, the average dairy cow herd in New Zealand (402 in 2014) has tripled in the last 30 years (NZ Dairy Statistics, 2014). Therefore, on many farms, there is an increasing reliance on automated systems to reduce labour costs and a decrease in experienced human contact on an individual animal basis. This less ‘hands on’ approach poses risks to animal health and welfare and there is an urgent need for automated systems that are capable of filling this gap in surveillance.

Sensing technologies, such as IRT, capable of automated, non-invasive detection of stress and disease are required for practical ‘farmer friendly’ assessments of animal health and welfare on-farm.The major advantage that IRT offers over many other non-invasive systems is that it lends itself to many on-farm applications (e.g., positioning in the milking shed and regular automated individual monitoring). IRT has potential to assist farmers in making critical decisions around areas such as early detection and treatment of health issues. Decisions which are made too late (e.g. treatment of disease) or not at all (e.g. missed inseminations) have a significant impact on the bottom line through lost production and hence significant economic value.

IRT images contain biometric information about that animal’s biological state that can be revealed and interpreted by a range of sophisticated analysis techniques. Unlike traditional disease and stress detection, any physiological change in the animal such as blood flow, inflammation or tissue composition can be detected as a change in the pattern of heat emitted.

How has IRT been used up until now?

Infrared thermography (IRT) has been used for many years for engineering and military applications and in human and veterinary medicine. The US Department of Defence have even used the technology as a lie detection tool. Yang & Yang (1992) reviewed the applications of IRT in various fields of medicine, including pharmacy and dentistry. It has also been used extensively in equine medicine to detect leg, hoof and back problems in racehorses. The use of IRT in other animal applications has been comprehensively reviewed by McCafferty (2007) and Stewart et al. (2005) and more recently in “Thermography: Current status and advances in livestock animals and veterinary medicine (2013). The technology has been demonstrated to be effective in the non-invasive identification of transport and other environmental stressors that alter heat loss (Schaefer et al., 1988; Stewart et al., 2007) as well as pain and fear in cattle (Stewart et al., 2008a,b; Stewart et al., 2009; Stewart et al., 2010; Stewart et al., 2007) and in elk (Cook et al., 2005).

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Cook, N.J.; Church, J.S.; Schaefer, A.L.; Webster, J.R.; Matthews, L.R.; Suttie, J.M. 2005: Stress and pain assessment of velvet antler removal from Elk (Cervus elaphus canadensis) and Reindeer (Rangifer tarandus). Online Journal of Veterinary Research 9: 13-25.

McCafferty, D.J. 2007: The value of infrared thermography for research on mammals: Previous applications and future directions. Mammal Review 37: 207-223.

Schaefer, A.L.; Jones, S.D.M.; Tong, A.K.W.; Vincent, B.C. 1988: The effects of fasting and transportation on beef cattle. 1. Acid-base-electrolyte balance and infrared heat loss of beef cattle. Livestock Production Science 20: 15-24.

Stewart, M.; Webster, J.R.; Schaefer, A.L.; Cook, N.J.; Scott, S.L. 2005: Infrared thermography as a non-invasive tool to study animal welfare. Animal Welfare 14: 319-325.

Stewart, M.; Webster, J.R.; Verkerk, G.A.; Schaefer, A.L.; Colyn, J.J.; Stafford, K.J. 2007: Non-invasive measurement of stress in dairy cows using infrared thermography. Physiology and Behavior 92: 520-525.

Stewart, M.; Schaefer, A.L.; Haley, D.B.; Colyn J.J.; Cook, N.J.; Stafford, K.J., Webster, J.R. 2008a. Infrared thermography as a non-invasive method for detecting fear-related responses of cattle to handling procedures. Animal Welfare 17, 387-393.

Stewart, M.; Stafford, K.J.; Dowling, S.K.; Schaefer, A.L.; Webster, J.R. 2008b: Eye temperature and heart rate variability of calves disbudded with or without local anaesthetic. Physiology and Behavior 93: 789-797.

Stewart, M.; Stookey, J.M.; Stafford, K.J.; Tucker, C.B.; Rogers, A.R.; Dowling, S.K.; Verkerk, G.A.; Schaefer, A.L.; Webster, J.R. 2009: Effects of local anesthetic and a non-steroidal anti-inflammatory drug on pain responses of dairy calves to hot-iron dehorning. J. Dairy Sci. 92: 1512-1519.

Stewart, M.; Verkerk, G.A.; Stafford, K.J.; Schaefer, A.L.; Webster, J.R. 2010: Noninvasive assessment of autonomic activity for evaluation of pain in calves, using surgical castration as a model. Journal of Dairy Science 93: 3602-3609.

Thermography: Current status and advances in livestock animals and veterinary medicine. 2013. Edited by F. Luzi, M. Mitchell, L.N. Costa and V. Redaelli. Brescia Foundation. Italy. ISBN 978-88-97562-06-1.

Yang, W.; Yang, P.P.T. 1992: Literature survey on biomedical applications of thermography. Bio-Medical Materials and Engineering 2: 7-18.