EFFECT OF ASCORBIC-ACID SUPPLEMENTATION IN DRINKING-WATER ON GROWTH-RATE, FEED CONSUMPTION AND FEED-EFFICIENCY OF BROILER-CHICKENS MAINTAINED UNDER ACUTE HEAT-STRESS CONDITIONS

Experiments were designed to determine whether supplemental ascorbic a cid (AA) would alleviate heat in growth rate, feed consumption and fee d efficiency of broiler chicks. A total of 450-day-old chicks were rea red at high ambient temperature ranging from 29 to 43 degrees C in bot h starter and finisher phases. The chicks were divided randomly into 3 equal groups (1, 2, 3). Group 1 was kept as control under normal requ ired temperature (21-35 degrees C) with average relative humidity of 4 0-85%, whereas group 2 and 3 were subjected to acute heat stress, temp erature ranging from 29 to 43.2 degrees C, with relative humidity of 4 0-85%. All the groups of birds were fed the same starter diet containi ng 12.6 MJ ME/kg and 22% crude protein (CP) and finisher diet comprisi ng 12.6 MJ ME/kg with 20% crude protein (CP). Proper water supply was assured to each group of birds during the experiment. Normal water was supplied to Group I and 3 whereas, in Group 2 water was supplemented with ascorbic acid at the rate of 20 mg/bird/day. High ambient tempera ture decreased (P < 0.01) weight gain in G3 by 9.1% as compared to bir ds in G1. The chicks in group 2 increased (P < 0.01) weight gain by 1. 68% and 10.9% when compared to G1 and G3. Birds in G2 consumed 8.3% an d 7.03% less feed with 11.1% and 22.2% better feed efficiency than tho se of in G1 and G3 respectively, whereas broilers in G1 consumed 1.25% more feed with 10% better feed efficiency than chicks in G3. An incre ase of 3.6% and 4.0% in body temperature was recorded in G2 and G3 as compared to G1 when they were subjected to acute heat stress. Mortalit y was higher in G3 by 20% and 45% than that in G1 and G2. Birds in G2 recorded the best performance with lower mortality as compared to G1 a nd G3.