Shinder D, Rusal M, Giloh M, Yahav S
Institute of Animal Science, the Volcani Center, Bet Dagan 50250, Israel.
Poult Sci. 2009 Mar;88(3):636-46. doi: 10.3382/ps.2008-00213.
The time just before hatch is critical, because the embryo shifts toward internal and external pipping. This study aimed to determine the beneficial effect of repeated acute reductions of the incubation temperature during the last phase of broiler embryogenesis on posthatch cold tolerance and on the development of ascites syndrome. Fertile eggs were incubated at 37.8 degrees C and 56% RH. At 18 and 19 d of incubation, 3 treatments were conducted, comprising 2 or 3 exposures to 15 degrees C for 30 or 60 min each. During these cold exposures, egg temperature was measured by infrared thermography to determine sensible heat loss from the eggs. At hatch, BW and body temperature were measured. At 3 and 14 d of age, chicks were challenged by cold exposure to 10 degrees C for 3 h. From 14 d of age onward, three-quarters of the chicks were raised under ascites-inducing conditions (AIC) and the others were raised under regular conditions. The sensible heat loss from the eggs was 512 +/- 66 cal and 718 +/- 126 cal for 30 and 60 min of cold exposure, respectively. No effect of treatment on hatchability was observed, but body temperature and BW were greater to significantly greater in the treated chicks. Cold challenges at 3 and 14 d of age revealed a relative thermoregulatory advantage of embryos exposed to cold for 60 min. Under AIC, fewer treated chickens than controls developed ascites. At 38 d of age, BW and relative breast muscle weight were numerically to significantly greater in the treated chicks than in the control chicks when both were raised under regular conditions, whereas no differences were observed among the chicks raised under AIC. Repeated brief acute cold exposures during the last phase of embryogenesis appeared to improve the ability of growing broilers to withstand low ambient temperatures during their life span. Moreover, chickens treated during embryogenesis improved their performance under regular growth conditions.
孵化前的这段时间至关重要，因为胚胎会转向内啄和外啄。本研究旨在确定在肉鸡胚胎发育最后阶段反复急性降低孵化温度对孵化后耐寒性和腹水综合征发展的有益影响。受精蛋在37.8摄氏度和56%相对湿度下孵化。在孵化的第18天和第19天，进行了3种处理，包括2次或3次暴露于15摄氏度，每次30或60分钟。在这些冷暴露期间，通过红外热成像测量蛋的温度，以确定蛋的显热损失。孵化时，测量体重和体温。在3日龄和14日龄时，将雏鸡暴露于10摄氏度环境中3小时进行冷应激试验。从14日龄起，四分之三的雏鸡在腹水诱导条件（AIC）下饲养，其余的在正常条件下饲养。冷暴露30分钟和60分钟时，蛋的显热损失分别为512±66卡路里和718±126卡路里。未观察到处理对孵化率有影响，但处理后的雏鸡体温和体重更高或显著更高。3日龄和14日龄的冷应激试验显示，暴露于冷环境60分钟的胚胎具有相对的体温调节优势。在AIC条件下，与对照组相比，接受处理的雏鸡患腹水的数量更少。在38日龄时，当两者都在正常条件下饲养时，处理后的雏鸡体重和相对胸肌重量在数值上或显著高于对照雏鸡，而在AIC条件下饲养的雏鸡之间未观察到差异。胚胎发育最后阶段反复短暂的急性冷暴露似乎提高了生长中的肉鸡在其生命周期内抵御低环境温度的能力。此外，在胚胎期接受处理的鸡在正常生长条件下表现更好。
