بررسي عملكرد رشد و بازدهي استفاده از نيتروژن در پاسخ به كمبود ميتونين در جوجه هاي گوشتي

Growth performance and efficiency of nitrogen utilization of broilers as affected by methionine deficiency

The present study was carried out to survey the effect of moderate deficiency of methionine on growth performance, carcass characteristics, and nitrogen efficiency of utilization of broiler chicks. In the growth study, male broilers were used in 16 floor pens. The chicks received the experimental diets from 1 to 42 days of age. All chicks were fed a commercial finishing diet from 42 to 49 days of age. The dietary treatments consisted of a methionine-deficient, basal diet and three further methionine-supplemented diets, which met 50, 75, and 100 percent of the deficiency of sulfur amino acid (SAA) requirements of the basal diet. The latest satisfied the requirement of SAA advocated by NRC (1994). Cystine met NRC (1994) recommendation with all diets. In balance study, the same dietary treatments as the growth study were used in cages. The experimental diets were fed from 10 to 17 days of age. Methionine supplementation of the basal diet improved weight gain and feed conversion ratio (P<0.05). Low methionine reduced proportions of skinless, boneless breast meat at 49d. Compared with methionine-supplemented diets, the methionine-deficient diet caused increased abdominal fat pad, decreased N retention and increased uric acid excretion.