Niacin requirement of broiler chickens fed a corn-soybean meal diet from 1 to 21 days of age.

Four experiments were conducted to determine the niacin requirement of broiler chicks fed a corn-soybean meal diet from 1 to 21 days of age. Day-old, feather-sexed, broiler chicks (1,408) were used. The unsupplemented basal diet of corn and soybean meal contained 21 mg of niacin per kg and .29% tryptophan, by calculation, and 25 mg of niacin per kg, by analysis. Eight pens and 6 pens, with 8 chicks per pen, were fed 0, 3, 6, 12, 33, and 66 mg of supplemental niacin per kg of diet in Experiments 1 and 2, respectively. Ten pens and 6 pens, with 8 chicks per pen, were fed 0, 3, 6, 12, and 15, and 0, 3, 12, 33, 66, and 132 mg of supplemental niacin per kg of diet in Experiments 3 and 4, respectively. The birds were weighed at 3 wk of age, and feed intake was determined. At the end of each experiment, each bird was evaluated for leg disorders. Using a two-phase regression analysis of the four experiments combined, a minimum requirement of total niacin (basal by analysis, plus supplemental) of 32 mg per kg of diet was found to be adequate in order to maximize broiler performance at 21 days of age.