Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9, Canada.
Poult Sci. 2021 Jan;100(1):103-109. doi: 10.1016/j.psj.2020.09.064. Epub 2020 Oct 6.
The objective of this study was to evaluate the effects of temperature (T)/relative humidity (RH) combinations and exposure duration (D) on the muscle tissue characteristics of layer pullets during simulated transport. While layer pullets are not processed for meat, muscle physiology can be used as an indicator to assess welfare. Pullets (n = 240) were randomly assigned to 1 of 5 T/RH combinations (-15°C uncontrolled RH [-15], 21°C 30%RH [21/30], 21°C 80%RH [21/80], 30°C 30%RH [30/30], and 30°C 80%RH [30/80]) and 2 D (4 or 8 h) in a 5 x 2 factorial arrangement (3 replications). Birds were weighed before exposure, crated (density 45.5 kg/m) and exposed to the conditions above. After exposure, birds were weighed (live shrink calculated) and slaughtered using a small-scale facility. Postslaughter, carcasses were eviscerated, and an initial pH was obtained from the right breast and thigh. Final breast and thigh pH and color values (lightness [L∗], yellowness [b∗], and redness [a∗]) were obtained 30 h postslaughter. Left breast muscles were frozen and analyzed for thaw and cook loss 4 wk postslaughter. Data were analyzed as a randomized complete block design via ANOVA (Proc Mixed; SAS 9.4), with farm of origin as block. Differences were considered significant when P ≤ 0.05. Live shrink (kg) was higher for pullets exposed to 30/30 and 30/80 compared with those exposed to 21/80 (P = 0.04) and for pullets exposed for 8 h compared with 4 h (P < 0.01). Breast muscle thaw loss (%) was higher in pullets exposed for 4 h compared with 8 h (P = 0.01). Breast and thigh muscle a∗ were higher for pullets exposed to 30/30 compared with 21/30 (P = 0.02). Thigh muscle b∗ was lower for pullets exposed to -15 compared with 21/80 (P = 0.05). Breast b∗ was higher for pullets exposed for 8 h compared with 4 h (P = 0.04). The results from this study demonstrates that increasing exposure D had minor effects on pullet muscle characteristics. In addition, layer pullets coped well with thermal stressors associated with simulated transport.
本研究旨在评估温度（T）/相对湿度（RH）组合和暴露持续时间（D）对层鸡在模拟运输过程中肌肉组织特性的影响。虽然层鸡不用于加工肉类，但肌肉生理学可用作评估福利的指标。将 240 只层鸡随机分配到 5 种 T/RH 组合（-15°C 未控制 RH [-15]、21°C 30%RH [21/30]、21°C 80%RH [21/80]、30°C 30%RH [30/30] 和 30°C 80%RH [30/80]）和 2 个 D（4 或 8 h）的 5 x 2 析因安排（3 个重复）中。暴露前对鸡进行称重，然后将鸡装入鸡笼（密度为 45.5 kg/m）并暴露在上述条件下。暴露后，鸡称重（计算活重损失），然后使用小型设施进行屠宰。屠宰后，从右胸和大腿处获得初始 pH 值。30 小时后获得最终的胸肌和大腿 pH 值和颜色值（亮度[L*]、黄度[b*]和红度[a*]）。左胸肌肉在 4 周后进行冷冻和解冻损失分析。数据通过 ANOVA（Proc Mixed；SAS 9.4）作为随机完整块设计进行分析，农场来源为块。当 P ≤ 0.05 时，差异被认为具有统计学意义。与暴露于 21/80 的鸡相比，暴露于 30/30 和 30/80 的鸡的活重损失（kg）更高（P = 0.04），与暴露 8 h 的鸡相比，暴露 4 h 的鸡的活重损失（kg）更高（P < 0.01）。与暴露 8 h 的鸡相比，暴露 4 h 的鸡的胸肌解冻损失（%）更高（P = 0.01）。与暴露于 21/30 的鸡相比，暴露于 30/30 的鸡的胸肌和大腿肌肉 a更高（P = 0.02）。与暴露于 21/80 的鸡相比，暴露于-15 的鸡的大腿肌肉 b更低（P = 0.05）。与暴露 4 h 的鸡相比，暴露 8 h 的鸡的胸肌 b*更高（P = 0.04）。本研究结果表明，增加暴露 D 对鸡肌肉特性的影响较小。此外，层鸡很好地应对了与模拟运输相关的热应激源。
