Performance of chicks subjected to thermal challenge

Abstract: The objective of this work was to evaluate the effect of thermal challenge at different intensities and durations on the production responses of 3 to 21-day-old broiler chickens. Two hundred and ten Cobb chicks were subjected to dry-bulb temperatures (tdb) of 27, 30, 33, or 36°C for the duration of 0, 1, 2, 3, or 4 days from the second day of life onwards. The experiment was carried out in four identical environmentally-controlled wind tunnels. Data on body mass (BM), feed intake (FI), and water intake (WI), all in grams, were monitored daily; and body weight gain (BWG), in grams, and feed conversion (FC) were also calculated. The effect of duration was not statistically significant. Empirical models were adjusted to relate BM, FI, and WI with tdb and bird age. The performance of chicks at 21 days of age was analyzed using the BM, FI, WI, BWG, and FC values. Overall, the development of chicks at 33 and 36°C was better than that of those subjected to the lower tdb of 30 and 27°C. The exposure of chicks to cold thermal challenge in early life can have a carry-over negative effect on their production performance up to 21 days of age.

摘要：本研究旨在评估不同强度与持续时长的热应激对3至21日龄肉鸡生产性能的影响。本实验选用210羽科宝（Cobb）肉鸡雏鸡，自孵化后第2日起，使其分别暴露于27、30、33或36℃的干球温度（dry-bulb temperature, tdb）环境中，持续时长为0、1、2、3或4天。实验在4台完全相同的环境可控风洞（environmentally-controlled wind tunnels）中开展。每日监测体质量（body mass, BM）、采食量（feed intake, FI）与饮水量（water intake, WI），所有指标单位均为克；同时计算体增重（body weight gain, BWG，单位为克）与饲料转化率（feed conversion, FC）。时长因素未表现出统计学显著性。本研究拟合了经验模型，以关联体质量、采食量、饮水量与干球温度及雏鸡日龄之间的关系。以21日龄雏鸡的体质量、采食量、饮水量、体增重及饲料转化率数据为指标，分析其生长性能。总体而言，33℃与36℃环境下雏鸡的生长发育表现优于27℃与30℃较低干球温度组。雏鸡在早期暴露于低温热应激环境，会对其直至21日龄的生产性能产生持续的负面影响。