early age feed restriction and thermal conditioning on growth ,carcass characteristics broiler chickens

in this study, effect early age feed restriction and thermal conditioning on growth ,carcass characteristics broiler chickens subjected to heat stress was evaluated. three hundred chicks (cobb500) were randomly divided into four equal groups as treatments including thermal conditioning group (tc), feed restriction-thermal conditioning group (tcfr), feed restriction group (fr) and control group (c), each group was replicated 5 with 15 birds per replicate.the groups tc and tcfr were exposed to thermal conditioning (38±1 c, for 24 h) at third day and the fr and tcfr groups were exposed to feed restriction for seven hours (10 am to 5 pm) at 7-14 days. mid (26 days) and late period (40 days) culture, blood samples were taken to measure serum biochemical parameters. thermal conditioning increased bw at 42d of age (p < 0.05). feed restriction decreased bw and feed intake at 21d of age(p < 0.05). in thermal conditioning birds at 26 d of age, triglyceride (p < 0.05) . in feed-restricted birds at 26 d of age, cholesterol (p < 0.05) were increasedin serum . also at 40 days of age, thermal adaptation of phosphorus was significantly increased (p < 0.05). thermal conditioning , feed restriction and their effects on serum blood glucose and total protein levels were not significant (p < 0.05). the results indicated that early age thermal conditioning improves broilers performance under summer heat stress condition.