Haron A, Shinder D, Ruzal M, Druyan S
The Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot, Israel.
Institute of Animal Science, Agricultural Research Organization, Volcani Center, Rishon Le Ziyyon, Israel.
Front Physiol. 2022 Jul 22;13:934676. doi: 10.3389/fphys.2022.934676. eCollection 2022.
The modern broiler is selected to exploit its full genetic potential, to sustain a rapid growth rate, and to lower the feed conversion rate (FCR). Recently reported reductions in FCR have been associated with augmented tissue formation at the expense of physiological functions such as thermoregulation. In turn, modern broilers exhibit a relatively low capability to balance energy expenditure under suboptimal ambient temperature. Hypoxic conditions at late incubation stages play a role in reforming metabolic plasticity. This work examined the effect of exposure to 12-h hypoxia (12H; 17% O) for three consecutive days (from E16 through E18), or continuous hypoxia exposure for 48 h (48H), from E16 through E17, as compared to standard incubation (21% O) on post-hatch performance of broilers maintained under suboptimal ambient temperatures (cold, hot, and diurnal cyclic ambient temperature). 12H chicks kept under hot ambient temperature had significantly lower body temperature (Tb) as compared to the control chicks. On day 42, both 12H and 48H chicks grown in the cyclic temperature room had significantly lower Tbs than controls. In parallel, from week 4, onward, 12H chicks had a significantly lower FCR than controls, and the 48H chicks demonstrated a lower FCR from week 5 and on. 12H and 48H broilers maintained under diurnal cyclic ambient temperature, exhibited significantly greater relative breast muscle weight, and a similar pattern was found in hypoxic broilers raised under standard and hot ambient temperatures. Hypoxic manipulation affects and create an adaptive bias in allocating metabolic energy between maintenance and growth, thus resulting in improved broiler performance, thermoregulation, and rearing under suboptimal environmental temperature.
现代肉鸡经过选育以充分发挥其遗传潜力，保持快速生长速度，并降低饲料转化率（FCR）。最近报道的FCR降低与以体温调节等生理功能为代价的组织形成增加有关。相应地，现代肉鸡在环境温度次优的情况下平衡能量消耗的能力相对较低。孵化后期的低氧条件在重塑代谢可塑性方面发挥作用。本研究考察了与标准孵化（21%氧气）相比，从胚胎第16天到第18天连续三天暴露于12小时低氧（12H；17%氧气），或从胚胎第16天到第17天持续暴露于低氧48小时（48H），对在环境温度次优（寒冷、炎热和昼夜循环环境温度）条件下饲养的肉鸡孵化后性能的影响。与对照雏鸡相比，在炎热环境温度下饲养的12H雏鸡体温（Tb）显著较低。在第42天，在循环温度室中饲养的12H和48H雏鸡的Tb均显著低于对照雏鸡。同时，从第4周起，12H雏鸡的FCR显著低于对照雏鸡，48H雏鸡从第5周起FCR较低。在昼夜循环环境温度下饲养的12H和48H肉鸡，其相对胸肌重量显著增加，在标准和炎热环境温度下饲养的低氧肉鸡也发现了类似模式。低氧处理会影响并在维持和生长之间分配代谢能量时产生适应性偏差，从而提高肉鸡在环境温度次优条件下的性能、体温调节能力和饲养效果。
