Effect of environmental temperature on muscle protein turnover and heat production in tube-fed broiler chickens

Abstract

The present experiments were undertaken to investigate the effects of environmental temperatures on growth, abdominal fat content, rate of muscle protein turnover, and heat production in tube-fed intact male broiler chickens. Plasma concentrations of thyroxine (Td), triiodothyronine (Ts), and corticosterone (CTC) were also examined. Chicks (15d old) were kept at different environmental tempera- (16,19,22,25,28,31, and 34") and given the experimental diet (200g crude proteid kg, 1337MJkg metabolizable energy) by tube three times daily throughout the 12d experimental period. In the hot conditions, except for 34", body-weight gain was significantly higher than in the cold conditions. Thus, food conversion ratios (food : gain ratios) were lower when the birds were exposed to the hot conditions other than 34". Likewise, abdominal fat content was significantly increased, and heat production was lower in the groups kept under the hot conditions other than 34". The rate of skeletal muscle protein turnover and plasma concentration of CTC were decreased when the birds were exposed to hot conditions other than 34", suggesting a role of CTC in the regulation of muscle protein turnover. Plasma coneenfrations of Tg and T j were significantly decreased as environmental temperature increased. These results clearly show that plasma concentrations of thyroid hormones and CTC are associated with accelerated muscle protein turnover and heat production.Environmental temperature: Muscle protein turnover: Heat production: Thyroid hormones: Corticosterone

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Metabolic and hormonal acclimation to heat stress in domesticated ruminants

“…Plasma urea nitrogen can originate from at least two sources: inefficient rumen ammonia incorporation into microbial proteins or from hepatic deamination of amino acids mobilized from the skeletal muscle. A better circulating indicator of muscle catabolism is either 3-methyl-histidine or creatine, both of which are increased in heat-stressed poultry (Yunianto et al, 1997), rabbits (Marder et al, 1990) and lactating cows (Schneider et al, 1988). Additional evidence suggesting that heat stress alters protein metabolism is decreased milk protein levels from heat-stressed cows Shwartz et al, 2009), and it appears that a S -and b-casein synthesis is most susceptible (Bernabucci et al, 2002b).…”

Adaptation to hot climate and strategies to alleviate heat stress in livestock production

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