Effect of Diet Composition on Feed Intake and Growth of Chicks Under Heat Stress. II. Constant vs. Cycling Temperatures

摘要: Abstract Broiler chicks 5 to 7 weeks of age were subjected a constant cool (14 ± 1 C) or hot (31 environment and fed diets varying in fat level energy nutrient density. Chicks gained significantly (P≤.01) more body weight the than environment. In both environments high fat-high density those low fat, there was no diet × temperature interaction. When temperatures cycled diurnally (cool, 14 22 C; hot, 33 C), as would occur under natural conditions, growth depression due heat stress less fat. The special benefit at probably result reduced increment. Under environment, pair-fed same feed intake (P≤.05) latter. These data indicated that factors other contributed associated with temperature. Thyroid size held slightly but not cyclic stress. This decrease thyroid suggested is practical limit on overcoming by nutritional means deleterious effects broilers.