evaluating the growth response of broiler chickens to probiotic supplementation under feed restriction

this experiment was carried out to evaluate the effect of probiotic supplementation and feed restriction on growth response in broiler chickens. for this purpose, 336 male broiler chickens of ross 308 were used. after housing, broilers allocated to experimental pens in a completely randomized design with factorial 2×3 arrangement. first and second groups considered as positive control group with supplemented probiotic or negative control group without supplemented probiotic, respectively, that birds in these groups had free access to feed. four other groups used a diet same as control groups, but from 7 to 35 days of age subjected to 4 or 8 hours feed restriction. four replicates of 14 birds were allocated to each experimental group. results of the experiment indicated the birds subjected to feed restriction had significantly lower feed intake and body weight gain during the first week of rearing compared to those fed ad-libitum. there was no significant difference between experimental treatments for feed intake. in the group of without probiotic, feed restriction for 8 hours led to reduce weight gain and carcass weight compare to those fed ad-libitum. but when use probiotic, weight gain and carcass weight was similar to those birds were fed ad-libitum. the results of this experiment showed that the use of probiotic can improve the performance of broilers under severe feed restriction.