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 acid (AA) would alleviate heat in growth rate, feed consumption and feed efficiency of broiler chicks. A total of 450-day-old chicks were reared at high ambient temperature ranging from 29 to 43 degrees C in both starter and finisher phases. The chicks were divided randomly into 3 equal groups (1, 2, 3). Group 1 was kept as control under normal required temperature (21-35 degrees C) with average relative humidity of 40-85%, whereas group 2 and 3 were subjected to acute heat stress, temperature ranging from 29 to 43.2 degrees C, with relative humidity of 40-85%. All the groups of birds were fed the same starter diet containing 12.6 MJ ME/kg and 22% crude protein (CP) and finisher diet comprising 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 temperature decreased (P < 0.01) weight gain in G3 by 9.1% as compared to birds 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% and 7.03% less feed with 11.1% and 22.2% better feed efficiency than those 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 increase 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. Mortality 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 and G3.