Effects of ambient temperature on heat increment of feeding and energy retention in growing broilers maintained at different food intakes

Abstract

Zero-activity heat production (HP), body temperature (Tb) and energy retention were measured in growing broilers maintained at 5 ambient temperatures (Ta) (14 degrees , 17 degrees , 22 degrees , 27 degrees and 32 degrees C) and at 5 feeding rates (ad libitum intake and 75%, 50%, 25% and 0% (fasting) of ad libitum). Zero-activity HP increased with decreasing Ta and increasing food intake. However, at 14 degrees C, zero-activity HP in birds fed ad libitum and 75% did not show further increase, but those in birds fed less than 75% of ad libitum increased rapidly. Results of the regression of zero-activity HP on Ta ranging from 32 degrees to 17 degrees C indicated that the slope was affected little by food intake, but the intercept decreased with decreasing food intake. Tb increased significantly with increasing food intake. There was little variation with Ta but, at and above 27 degrees C, a slightly increased Tb was observed only in birds fed ad libitum. Overall effects of Ta and food intake on HIF (% TME intake) were not found, but HIF tended to increase with decreasing food intake at 14 degrees C. Total energy retention and energy retention as fat decreased with decreasing Ta and food intake, although energy retention as protein decreased only with decreasing food intake. Results obtained here suggest that availability of TME is affected little by Ta ranging from 32 degrees to 17 degrees C and that HIF is utilised, in part, to maintain Tb at any Ta.

Crude protein and metabolizable energy levels for layers reared in hot climates

“…The main consequence of exposure to heat is that birds reduce their feed intake (Geraert et al, 1996) in order to diminish metabolic heat production in an attempt to maintain their body temperature (Koh & Macleod, 1999); however, major reduction in energy and nutrient intake may compromise productivity (Leeson et al, 2000).…”

Effects of supplementation of betaine hydrochloride on physiological performances of broilers exposed to thermal stress

“…9,10 Drastic decline in feed intake occurs in heat-stressed birds as a physiological response to minimize intrinsic heat production and to maintain the thermal homeostasis, thus bringing down feed efficiency, live weight gain, and survival rates. [11][12][13][14] Lower breast-meat yield and higher carcass-fat deposition are the other deleterious effects of heat stress that lower the economic value of broiler carcasses. 10,11,15 Betaine, the trimethyl derivative of the amino acid glycine, is a naturally occurring compound distributed widely in many plants and animal tissues.…”

Animal Feed Production and Contamination by Foodborne Salmonella

“…Feed intakes of laying hens can vary, depending on metabolizable energy intakes and environmental temperature (North, 1978;Jurgens, 1993). Ad libitum broiler intake varies depending on numerous factors, such as growth rate, diet composition, ambient temperature and corticosterone concentration (Dale and Fuller, 1980;Gous, 1998;Koh and Macleod, 1999;Nasir et al 1999). Dale and Fuller (1980) reported that feed to gain ratios for poultry may also depend upon species, as exotic species such as ostriches and cockerels have been shown to metabolize energy more effi ciently than poultry (Cilliers et al, 1999).…”