Season, Transport Duration and Trailer Compartment Effects on Blood Stress Indicators in Pigs: Relationship to Environmental, Behavioral and Other Physiological Factors, and Pork Quality Traits.

The objective of this study was to assess the effects of the season, travel duration and trailer compartment location on blood creatine-kinase (CK), lactate and cortisol concentrations in 384 pigs and assess their relationships with trailer temperature, heart rate and gastrointestinal tract temperature (GTT), behavior, carcass damage scores and meat quality. Blood CK was greater in pigs transported in summer (p = 0.02), after 18 h transportation (p < 0.001) and in pigs located in C4, C5 and C10 (p = 0.002). In winter, the concentration of blood lactate was higher (p = 0.04) in pigs transported for 6 h in C5. Pigs located in C10 showed higher (p = 0.01) concentration of cortisol than those transported for 18h in C4 in summer. The highest correlations were between blood cortisol and GTT (r = 0.53; p < 0.001), and between blood CK and GTT (r = 0.41; p < 0.001), truck temperature (r = 0.42; p < 0.001), and pHu in the longissimus muscle (r = 0.41; p < 0.001). In conclusion, although increased blood cortisol and CK levels appear to indicate a physical stress condition in transported pigs, the weak to moderate correlations with environmental and other animal welfare indicators suggest that blood stress parameters can only be used as a complementary measurement in the assessment of the pigs' response to transport stress.

Welfare of Pigs Being Transported over Long Distances Using a Pot-Belly Trailer during Winter and Summer.

A total of 2,145 pigs were transported for 8 h in summer (six trips) and winter (five trips) using a pot-belly trailer accommodating pigs in four locations (upper deck or UD, bottom-nose or BN, middle deck or MD and bottom deck or BD). Heart rate of pigs during loading and transportation and lactate and creatine kinase (CK) concentrations in exsanguination blood were measured. Meat quality was evaluated in the Longissimus thoracis (LT), Semimembranosus (SM) and Adductor (AD) muscles. During summer, pigs loaded in the UD and MD had higher (P < 0.05) heart rate at loading compared to those located in the BD and BN. Blood lactate and CK concentrations were higher (P < 0.001) in winter than in summer. Lactate concentration was higher (P = 0.01) in the blood of pigs transported in the BN. Pigs transported in the BN had higher pHu values in the LT, SM and AD muscles (P = 0.02, P < 0.001 and P = 0.002, respectively) and lower (P = 0.002) drip loss values in the SM muscle. This study confirms that some locations within the PB trailer have a negative impact on the welfare of pigs at loading and during transport with more pronounced effects in the winter due to the additive effect of cold stress.