Determination of the amino acid requirements and optimum dietary amino acid pattern for growing Chinese Taihe Silky fowls in early stage

A mathematical model has been constructed to estimate the amino acid requirements for growing Taihe silky fowls in early stage. A requirement was taken as the sum of the needs for maintenance, for gain in carcass weight without feathers, and for the feathers. The maintenance requirement was considered to be the sum of the needs for replacing skin and intestinal losses and for the obligatory creatinine excretion in the urine. A comparative slaughter trial and nitrogen balance trials with growing and adult Taihe silky fowls, respectively, were conducted to estimate the parameters in the model. The amino acid requirements were then calculated with the constructed models. The results showed as following: the replacement needs for skin nitrogen loss was determined at 213.41 mg/d for adult male fowls (body weight 1.60 kg); creatinine excretion in these birds was 4.04 mg/d. when fed an nitrogen-free diets, the adult male fowls with body weight 1.60 kg excreted a total of 246.10 mg/d endogenous nitrogen. The net protein requirement for maintenance was estimated at 11.24 mg/w(g)(0.75)/d. Per gram of body weight gain contained 27.18 mg carcass nitrogen for growing birds in early stage, but feathers nitrogen in per gram of body weight gain increased with age. The amino acid requirements for growing Taihe silky fowls were slightly higher than for starting and growing pullets, but lower than that of broiler chicks. The amino acid requirements patterns changed with weeks of age.