Zulkifli I, Che Norma M T, Israf D A, Omar A R
Department of Animal Science, University Putra Malaysia, Serdang, Selangor.
Poult Sci. 2000 Oct;79(10):1401-7. doi: 10.1093/ps/79.10.1401.
This study was conducted to determine whether early age feed restriction improves heat tolerance in female broiler chickens. Chicks were brooded for 3 wk and then maintained at 24+/-1 C. On Day 0, chicks were assigned to one of four feeding regimens; each regimen was applied to four cages of chicks. The feeding regimens were 1) ad libitum feeding (ALF); 2) 40% feed restriction at 4, 5, and 6 d of age (F40); 3) 60% feed restriction at 4, 5, and 6 d of age (F60); and (4) 80% feed restriction at 4, 5, and 6 d of age (F80). From 35 to 41 d of age, all birds were exposed to 38+/-1 C for 2 h/d. Serum concentrations of glucose were elevated by the heat challenge, but were not affected by the feeding regimen. The heat treatment resulted in hypocholesteremia among ALF and F80 chicks, whereas the concentrations increased and remained constant in the F60 and F40 birds, respectively. Subjecting chicks to F60 improved growth and survivability and reduced heterophil to lymphocyte ratios (H/L) in response to the heat treatment as compared with the ALF and F80 regimens. The survivability rate and H/L of F40 chicks were similar to those attained by chicks on other regimens. Newcastle disease antibody titer of ALF birds declined with duration of heat treatment. It is concluded that the F60 regimen is beneficial for alleviating, at least in part, the detrimental effects of heat stress in female broiler chickens.
本研究旨在确定早期限饲是否能提高雌性肉鸡的耐热性。雏鸡饲养3周后，维持在24±1℃环境中。在第0天，将雏鸡分为四种饲养方案之一；每种方案应用于四笼雏鸡。饲养方案分别为：1）自由采食（ALF）；2）4、5和6日龄时40%限饲（F40）；3）4、5和6日龄时60%限饲（F60）；4）4、5和6日龄时80%限饲（F80）。在35至41日龄期间，所有鸡只每天暴露于38±1℃环境中2小时。热应激使血清葡萄糖浓度升高，但不受饲养方案影响。热处理导致ALF和F80组雏鸡出现低胆固醇血症，而F60和F40组雏鸡的胆固醇浓度分别升高并保持稳定。与ALF和F80方案相比，F60组雏鸡在热处理后生长和存活率提高，异嗜性粒细胞与淋巴细胞比例（H/L）降低。F40组雏鸡的存活率和H/L与其他方案的雏鸡相似。ALF组鸡新城疫抗体滴度随热处理时间下降。研究得出结论，F60方案至少在一定程度上有利于减轻雌性肉鸡热应激的有害影响。
