Effects of Early Feed Restriction on the Occurrence of Compensatory Growth, Feed Conversion Efficiency, Leg Abnormality and Mortality in Unsexed Broiler Chickens Reared in Cages

Two experiments were conducted to evaluate the effect of early feed restriction on growth, feed conversion ratio (FCR) and mortality in unsexed broiler chickens.In Experiment 1, 350 one-day-old broiler chickens were divided into 7 groups.Each treatment group was represented by five replicates of ten broilers each.One group was fed ad libitum as the control group and the other six groups were fed 25% ad libitum (25% multiplied by amount of feed intake of ad libitum chickens at the previous day) for 4 or 6 days, 50% ad libitum for 4 or 6 days, and 75% ad libitum for 4 or 6 days.In experiment 2, 500 broiler chickens were divided into 10 groups.Each treatment group was represented by five replicates of ten broilers each.One group was fed ad libitum as the control group.Three ages of feed restriction initial timing (2, 4 or 6 days of age) and three types of feed restriction (physical restriction, meal feeding and diet dilution) were used (3×3) in both experiments.They were feed-restricted for 6 days.Results showed that restricted broilers exhibited compensatory growth in both experiments except for diet dilution groups.In both experiments, FCR of restricted broilers was higher, whereas feed intake of them was lower during restriction period.FCR of restricted broilers was lower upon refeeding.Mortality was inconsistently affected by early feed restriction.Leg abnormality was lower in restricted broilers in both experiments.Level of feed restriction significantly influenced body weight, FCR and feed intake of restricted broilers (p<0.05),but duration of feed restriction had no effect.Type of restriction significantly affected body weight, feed intake and FCR (p<0.05).It appeared that to achieve the best result (complete compensatory growth and better FCR), broilers should be restricted at 25% ad libitum for 6 days (Experiment 1).Meal feeding started at 2 days of age would show the best performance (Experiment 2).(Asian-Aust.