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

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.

Influence of hot exposure on 12-week-old turkey hen physiology, welfare, and meat quality and 16-week-old turkey tom core body temperature when crated at transport density.

The influence of hot conditions on 12-week-old turkey hens and 16-week-old toms while crated at transport density was evaluated. Forty-eight hens and 48 toms (8 birds per flock × 3 flocks × 2 humidity levels) were used in neutral treatments (trt; 20°C), and 16 hens and 16 toms (8 birds per flock × 1 flock × 2 humidity levels) were used in the hot trt (35°C). Birds were placed in crates at a transport stocking density of approximately 83 kg/m2, then inside a pre-conditioned chamber for 8 hours. Live shrink, core body temperature (CBT), heterophil/lymphocyte (H/L) ratio, and breast and thigh pH and color were recorded. Differences were declared significant at P ≤ 0.05. Live shrink after exposure to the 35°C trt (4.92%) was greater (P < 0.0001) than when birds were exposed to 20°C (1.48%). The 35°C trt (P < 0.0001) had higher Δ CBT (final minus initial) compared to the 20°C trt. The 35°C trt also caused higher (P < 0.0001) H/L ratio, 4.07 vs. 1.57 for the 20°C trt. Breast (P = 0.0110) and thigh pH levels (P < 0.0001) measured 27 h postmortem were lower for the 35°C trt at 5.64 and 5.73 compared to the 20°C trt at 5.70 and 5.92, respectively. Breast meat from birds exposed to 35°C was darker (P < 0.0001), while the color of thigh meat was unaffected. Toms quickly became distressed in the hot conditions, forcing those tests to be aborted. Only CBT data were analyzed. The CBT increased at a mean rate of 0.09°C/min for hens at both RH levels, while the CBT of toms increased at 0.12 and 0.18°C/min when exposed to 35°C, 30%; and 35°C, 80%, respectively. Exposure to hot temperatures caused higher CBT, greater live shrink, and greater H/L ratio. Toms were more greatly affected than hens to the hot trt, with CBT increasing at a greater rate.

The impact of graded levels of day length on turkey health and behavior to 18 weeks of age.

The impact of graded levels of day length on turkey health and behavior was determined in hens and toms raised to 18 wk of age. Birds were allocated to one of 4 lighting treatments (trt) providing 14 (14L), 17 (17L), 20 (20L), and 23 (23L) h of day length. Two time-replicated trials were completed with each, providing 2 rooms per lighting trt and each room having 3 hen (n = 720) and 3 tom (n = 480) pens. Data collection included gait score (GS), the incidence of footpad dermatitis (FPD), breast buttons and blisters, ocular size and pressure (males only), and behavioral observations (males only). Data were analyzed using SAS 9.3 based on a completely randomized design nested within 4 lighting trt. Regression analysis established relationships between response criteria and day length. Differences were considered significant at P ≤ 0.05 and trends noted at P ≤ 0.10. Gait score, FPD, and the incidence of breast buttons and blisters were assessed on 5 birds per pen at 11 and 17 wk of age. Average GS increased linearly with day length at 11 and 17 wk for both hens and toms, but the effect was larger in toms. Day length did not affect FPD, but more lesions and severe scores were found for hens than toms. The presence of breast buttons and blisters increased linearly with day length (11 wk) with the effect on blisters predominately seen in toms. Eye weight and size increased with increasing day length at 12 and 18 wk. Ocular pressure was not affected by day length. Infrared cameras recorded tom behavior over a 24 h period, and behaviors were classified over 10-min intervals using a scan sampling technique at 11 and 17 wk. Alterations in behavioral repertoire were observed with a linear increase in inactive resting and a linear decrease in standing, walking, preening, and environmental and feather pecking behaviors with increased day length. To conclude, day length affected bird mobility and incidence of breast blisters in an age- and gender-specific manner, and time spent inactive increased with longer day length.

The impact of graded levels of daylength on turkey productivity to eighteen weeks of age.

The impact of graded levels of day-length on the productivity of hens and toms was studied in two trials. Daylength treatments (trts) were 14 (14L), 17 (17L), 20 (20L), and 23 (23L) h and were started at 10 d of age. Turkeys (720 hens and 480 toms) were randomly allocated to 8 rooms (2 rooms per lighting trt) with six pens (3 hen--30 per pen and 3 tom--20 per pen) per room in each trial. Body weight (BW) was assessed at 0, 10, 21, 42, 63, 84, and 126 d of age; feed consumption (FC) was measured for the time periods between body weight determinations and feed efficiency (G:F; g of gain/g of feed) was calculated from BW and FC values. Birds were checked daily for mortality and culls, and affected birds were sent for necropsy. Data were analyzed according to a completely randomized block design with trial as the block and rooms nested within lighting trts. Regression analysis was used to study the relationship between dependent variables and daylength. Significance was declared at P≤ 0.05 and trends at P≤ 0.10. At both 21 and 42 d, body weight increased linearly with increasing daylength. At 84 d weights of toms decreased in a quadratic fashion and hen weights were unaffected. At 126 d, both tom and hen weights decreased linearly as daylength increased, with the magnitude of response gender dependent. Feed consumption corresponded with body weight changes, increasing for d 10 to 21, and 21 to 42 and decreasing for d 63 to 84, 84 to 105, and 105 to 126 with increasing daylength. Feed efficiency (G:F) was not affected by daylength for 10 to 84, 10 to 105 and 10 to 126 d periods. The incidence of mortality and culling was not affected by daylength for the 10 to 84 d period, but increased in a quadratic manner with increasing daylength for the 10 to 105 and 10 to 126 d periods. To conclude, daylength affects the growth and feed intake of turkeys in an age and gender-specific manner, and mortality and culling increase with longer daylength.