Abstract 270

Njoku,-PC

Dep. Animal Science, Faculty of Agriculture, Ahmadu Bello Univ., PMB 1044, Zaria, Nigeria.

Animal-Feed-Science-and-Technology. 1986, 16: 1/2, 17-24; 15 ref.

Two experiments, the first lasting 8 weeks and the second 9 weeks, were made with 1 day-old Ross broiler chicks to evaluate the effect of dietary ascorbic acid supplementation on performance during the hot months (March-May) of the year in Zaria, Nigeria. In experiment 1, 0, 200, 400 or 600 mg ascorbic acid/kg feed was added to a maize and soyabean meal basal diet. In experiment 2, 100, 200 or 300 mg ascorbic acid per kg feed was added to portions of the control diets. The starter and finisher diets in each experiment were formulated to be isonitrogenous and isoenergetic. Results from experiment 1 showed that by 8 weeks, ascorbic acid supplementation had linear (P<0.05) and quadratic (P<0.001) effects on body weight gain in the broilers, gain being highest at 200 mg ascorbic acid/kg feed. Feed intake was unaffected by treatment, but feed:gain ratio at both 4 and 8 weeks showed linear (P<0.05) and quadratic (P<0.01) responses. In experiment 2, the following respective average 8-week body weight gains (kg), obtained for 0, 100, 200 and 300 mg ascorbic acid/kg feed were 1.65, 1.72, 2.08, 1.92. Feed:gain response was also best with ascorbic acid 200 mg/kg. In periods of heat stress that occur in some months in the tropics, dietary supplementation of broiler chicken diets with ascorbic acid 200 mg/kg is necessary and economically advantageous.