Three experiments were conducted to evaluate infrared technology as a tool for predicting transport stress and pale soft and exudative (PSE) meat traits in market pigs. Experiment 1 compared the ability of two digital infrared thermographic cameras [research grade (RG) and consumer grade (CG)] to detect temperature change in market pigs (N=168 market pigs, BW=111.5±13.2 kg). There were two treatment groups: Control and Handling treatment (N=84 per treatment). Control pigs remained in their home pen while Handling treatment pigs received a mild handling stressor (walking a distance of approximately 100m). The ocular (OT) and body temperature (BT) of all pigs were measured using both cameras at two time points: before (baseline) and approximately 1 hr later (after Handling treatment pigs were moved). Experiment 2 compared pre- and post-transport ocular and body temperatures of market pigs to determine if pre-transport temperatures were predictive of post-transport temperatures using CG digital infrared cameras. In Experiment 2, pigs (N=120, BW=105.1 ± 4.9 kg) were transported in five replicates (20-25 pigs/replicate) for ~2 h to an abattoir during summer. Thermographic ocular and body images were collected from each pig at three time points; twice before and once after transport (T1: three days prior to transport, T2: one day before transport, and T3: in lairage post-transport). Experiment 3 was conducted using animals from Experiment 2. The objective of Experiment 3 was to determine if infrared technology can predict meat quality based on the post-transport ocular and body temperatures (T3) collected at the packing plant prior to slaughter. At slaughter, blood samples were collected for cortisol, glucose and lactate analyses. Carcass pH was taken at 1 and 3 h postmortem and loin samples were collected for meat quality (ultimate pH, meat color, drip loss and meat tenderness) assessment. Data collected in Experiment 1 were analyzed using Pearson correlations, linear regression and a mixed model with main effects: treatment, time and their interaction, with pen as a random factor using SAS (SAS 9.4). Data collected in Experiment 2 were analyzed using Pearson correlations and regression analysis, while data collected in Experiment 3 were analyzed using Pearson correlations, linear regression and mixed model analyses in SAS. In Experiment 1, the infrared measures from RG and CG cameras were positively (r=0.93, P<0.05) correlated. In addition, handling treatment led to increases (P<0.05) in body and ocular temperatures in handled pigs compared to unhandled controls. In Experiment 2, significant positive correlations were found between T1 and T2 body temperatures. Moreover, the regression analyses showed strong associations (r2=0.80, P=0.01) between T1 and T2 body temperatures. Correlations between T1 and T2 ocular temperatures were non-significant, and there were no relationships between T1 and T3, or T2 and T3 temperatures for body or ocular measures. Experiment 3 showed positive correlations (r=0.40, P<0.010) between IR ocular temperatures post-transport and blood cortisol at slaughter, suggesting a relationship between temperature and stress physiology in pigs. Meat yellowness (b*) increased with elevated body temperatures (r=0.2, P <0.001). Meat tenderness increased with increase in IR ocular and body temperatures post-transport (r=-0.51, P<0.001). Pigs with high IR body temperatures post-transport/pre-slaughter had poorer meat quality characterized by pale soft and exudative (PSE), moderately pale soft and exudative (MPSE), pale firm and normal (PFN) carcasses postmortem. In conclusion, no correlation was found between on-farm and post-transport IR temperatures. However, IR body temperatures post-transport were predictive of meat quality traits in market pigs. Results in this thesis support the potential for infrared technology to identify stressed or febrile pigs on-farm and to predict pork quality before slaughter. Automation of infrared technology in commercial barns or packing plants could allow real-time data collection and monitoring of pig health for improved animal welfare and meat quality
