Effects of high ambient temperature on growth rate, feed consumption and feed efficiency of broilers fed high energy and protein diets

One day old broilers were reared at ambient temperature ranging from 27 to 42 degrees C for 42 days. The chicks were divided into 4 different groups (1, 2, 3 and 4). Group 1 was kept as control under normal temperature (21-28 degrees C) with average relative humidity of 39 to 85% whereas groups 2, 3 and 4 were reared at high ambient temperature ranging from 29 to 42 degrees C, with average relative humidity of 45 to 89%. Group 1 and 2 received the same diets (12.6 MJ ME/kg, 22% of crude protein [CP] in starter and 12.6 MJ ME/kg and 20% of CP in finisher diets). Group 3 received high energy and protein diets (13.5 MJ ME/kg, 24% CP in starter and 13.0 MJ ME/kg, 23% CP in finisher diets). While group 4 was fed very high energy and protein diets (14 MJ ME/kg, 25% of CP in starter and 13.5 MJ ME/kg and 23.5% of CP in finisher diets). increasing ambient temperature decreased (P < 0.01 weight gain of chicks in G2 by 5.6% as compared to G1. The chicks in G3 increased (P < 0.01) weight gain by 1.8% and 7.3%, respectively, as compared to G1 and 2. Broilers in G4 recorded the highest weight gain. The increase was higher (P < 0.01) by 6.5, 11.7 and 4.8% as compared with group 1, 2 and 3, respectively. Chicks in G4 consumed less feed by 13.1, 10.9 and 4.7% with better feed efficiency by 20.7, 25.6 and 10.3% than those of G1, 2 and 3, respectively. Broilers in G1 consumed 2% more feed and recorded better feed efficiency than chicks in G2. Group 3 consumed 8 and 5.9% less feed and was more efficient in converting feed into liveweight than those of G1 and 2. The elevation of body temperature was measured as 5.5, 6.8 and 6.8% in groups 2, 3 and 4, respectively, during acute heat stress as compared to broilers in G1.