Detection of Bruising in Holstein Slaughter Cows with Infrared Thermography

Identifying severe bruising in livestock before slaughter is valuable because bruises are likely a source of pain for the animal that cannot be seen by visual inspection. This bruising may result in major trim losses because bruised tissue is considered unfit for human consumption. The objective of this study was to determine if bruising could be detected under the hide of live Holstein cull cows with infrared thermal imaging technology. A FLIR E8 thermal imaging camera was utilized to capture heat emission images pre-hide removal and post hide removal for 36 Holstein cull cows. Images were collected approximately 2 m from each cow and associated carcass images were examined on FLIR Tools software to determine if and where inflammation was detected on the carcass. Trimming occurs throughout the slaughter process, but carcasses may be ‘railed out’ if additional trimming is necessary. Trim loss was collected from railed out carcasses and weighed. The impact of rail-out status on trim loss was significant (P < 0.0001). Carcasses that were railed out (n = 15) yielded 16.2 ± 2.0 kg of trim loss. Carcasses that were not railed out (n = 21) did not experience additional trim loss. Carcasses railed out for additional trimming where inflammation suggested bruising existed (n = 7) yielded 21.0 ± 4.8 kg of trim loss. Carcasses railed out for trimming where thermography did not detect bruising (n = 4) yielded 12.6 ± 6.4 kg of trim loss. The relationship between thermographic detection of bruises and trim loss among railed-out carcasses was not significant (P = 0.3200). Inflammation that predicted rail-out events was 63.64% while carcasses in which rail-out was not detected by thermography was 36.36%. It appears that infrared thermography has potential to identify carcass bruising but additional investigation is warranted to understand its limitations.