Yalçin S, Settar P, Ozkan S, Cahaner A
Aegean University, Faculty of Agriculture, Izmir, Turkey.
Poult Sci. 1997 Jul;76(7):921-9. doi: 10.1093/ps/76.7.921.
Hot climate is a major limiting factor of broiler production in tropical and subtropical regions. The use of standard stocks in hot climates may result in large economic losses because genotypes selected in temperate climates may respond differently to the high ambient temperatures in hot regions or seasons. The summer and fall in Izmir, Turkey, provided the natural hot and temperate climates, respectively, for this study. Broiler chicks were obtained from three commercial stocks, all bred in temperate climates. Male and female chicks, 60 per pen, were housed in four pens per stock per season. Individual BW was determined at hatch, and at 4 and 7 wk of age. Feed consumption and efficiency were determined per pen. Feathering was scored at 4, 5, and 6 wk of age. Body temperature was measured twice on three birds per sex per pen, 16 h and immediately before slaughter, and feather weight was determined for each of these birds. The two seasons clearly differed in ambient temperature at the broiler house, and consequently, BW at 7 wk was significantly lower in the summer than in the fall in all stocks, with an average reduction of 23%. The season effect was largest (33.5%) on BW gain from 4 to 7 wk, along with 23 and 15% reductions in feed consumption and efficiency, respectively, during these 3 wk. A significant season by stock interaction was detected for BW gain from 0 to 4 wk and 4 to 7 wk. The three stocks exhibited similar 4- to 7-wk BW gains under the temperate fall climatic conditions, but differed significantly in the summer. These differences were not related to normal differences in feather coverage or body temperature, suggesting that standard broiler stocks must be tested in hot climates in order to find the one most suited to these conditions.
炎热气候是热带和亚热带地区肉鸡生产的主要限制因素。在炎热气候下使用标准鸡种可能会导致巨大的经济损失，因为在温带气候下选育的基因型对炎热地区或季节的高环境温度可能有不同反应。土耳其伊兹密尔的夏季和秋季分别为本研究提供了自然炎热和温和的气候条件。肉鸡雏鸡来自三个均在温带气候下培育的商业鸡种。每个鸡种每个季节在四个鸡舍中饲养雄性和雌性雏鸡，每舍60只。在雏鸡出壳时、4周龄和7周龄时测定个体体重。测定每个鸡舍的采食量和饲料效率。在4周龄、5周龄和6周龄时对羽毛生长情况进行评分。对每个鸡舍中每种性别的三只鸡在16小时和屠宰前立即测量体温，并测定这些鸡的羽毛重量。肉鸡舍的环境温度在两个季节明显不同，因此，所有鸡种在夏季7周龄时的体重均显著低于秋季，平均降低23%。季节效应在4至7周龄的体重增加方面最大（33.5%），在这3周内采食量和饲料效率分别降低23%和15%。在0至4周龄和4至7周龄的体重增加方面检测到显著的季节与鸡种交互作用。在温带秋季气候条件下，三个鸡种在4至7周龄时的体重增加相似，但在夏季差异显著。这些差异与羽毛覆盖或体温的正常差异无关，这表明必须在炎热气候下对标准肉鸡鸡种进行测试，以便找到最适合这些条件的鸡种。
