Effect of nutritional substances on regulation of thermogenesis in chicken muscle

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1. Construction and improvement of the system. In 2002, an indirect, open-circuit calorimeter system was constructed, but this system had a little problem with the accuracy. In 2003, dehumidifiers were added to the respiratory chambers to improve accuracy. In 2004, the number of the respiratory chamber was increased, and consequently, the stream selector and control program were modified. In 2005, this system had a problem with the control system, probably because of a cumulative problem in the operating system. Therefore, the operating system was change from Win-me to Win-XP, and the control program and air-mixing fans were modified in this opportunity.2. Ambient temperature and diet-induced thermogenesis (DIT). Feeding enough energy to chickens kept at low ambient temperature is not easy, because of limited feed intake. In this experiment, required nutrients at low ambient temperature were examined. The results obtained here showed that body temperature was maintained by increased energy in diets, but incidence of ascites increased probably because of impaired cardiovascular function, such as hyper-tension.3. Nutrients and heat production. The relationship between dietary protein level and heat production in chickens was examined. Thermogenic effect of protein was remarkable and dose-dependent, but further effect was not observed when protein level exceeded 20%. In addition, the age of chickens seems to have a relation to the degree of heat production. The relationship between dietary fat level and heat production was examined. Fat had little thermogenic effect. Although fatty acids were not believed to be useful respiratory substrates, acetate was used as a respiratory substrate faster than glucose.