Effect of a change in environmental temperature on heat tolerance in laying fowl.
Laying hens when transferred from accommodation at an ambient temperature (Ta) of 30 degrees C to one of 20 degrees C failed to acclimatise to intermittent heat stress (Ta 38 degrees C) commencing one day after the transfer. After 21 d of intermittent exposure to 38 degrees C these hens showed little or no increase in heat tolerance, whereas hens living constantly at either Ta 20 degrees C or 30 degrees C acclimatised normally. The failure to acclimatise was also observed when hens were transferred from Ta 30 degrees C to 5 degrees C but not when transferred from Ta 5 degrees C to 30 degrees C. The failure to acclimatise following transfer from a warm to a cool environment was accompanied by an increase in food intake; if food intake was not allowed to increase the hens acclimatised normally to heat stress.
D000064:Acclimatization; D000818:Animals; D002645:Chickens / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D006358:Hot Temperature; D011201:Poultry Diseases / Q000503:physiopathology*; D013312:Stress, Physiological / Q000662:veterinary*