Effects of cold exposure on physiology, meat quality, and behavior of turkey hens and toms crated at transport density

Abstract

The impact of cold exposure while crated at a density characteristic of transport (83 kg/m2) was assessed in 12-wk-old turkey hens and 16-wk-old toms. Turkeys (72 toms, 72 hens) were randomly divided into 3 male and 3 female groups: 2 moderate 20°C groups with either 30% or 80% RH and a cold group exposed to –18°C, with uncontrolled, high RH. Groups of 8 birds (one replicate unit) were observed in a climate-controlled chamber for 8 h prior to slaughter. Core body temperature (CBT), live shrink, heterophil-lymphocyte ratio (HLR), and change in blood glucose levels were assessed; meat quality measures included thigh and breast muscle pH and L*, a*, and b* color values. Significance was declared at P ≤ 0.05. Live shrink in hens exposed to –18°C (2.8%) was greater (P = 0.001) than those in the 20°C treatments (1.5%). CBT in hens had a tendency to decrease (P = 0.070); no differences in Δ blood glucose or HLR were detected. Thigh pH was higher in the –18°C treatment (hens: 6.39; toms: 6.08) than in both 20°C groups. Color values (L*, a*, and b*) were measured 27 h postmortem. In the –18°C exposed hens, breast L* values were lower, and thigh a* and breast b* values were higher than in both 20°C treatments. No differences were detected in live shrink, CBT, HLR, or color values among toms. Behavior differences were noted between treatments; more time was spent huddling, shivering, preening, and with feathers ptiloerected in cold-exposed turkeys. Generally, cold exposure resulted in higher live shrink, darker meat with greater redness, and a tendency for CBT and blood glucose to decrease, with larger male turkeys experiencing fewer changes.