Effects of Early Quantitative Feed Restriction on Live Performance and Carcass Composition of Male Broilers Grown for Further Processing

Three trials with identical design were conducted to examine the effects of early feed restriction on broiler chickens grown for further processing. Diets provided a minimum of 107.5% of NRC amino acid requirements, maintained in proportion to dietary energy levels. Varying energy levels were obtained by adding 0, 3, and 6% poultry oil. Diets within each age period (starter, 0 to 21 d; grower, 21 to 42 d; and finisher, 42 to 63 d) had similar calorie:protein ratios. Feed was given ad libitum for the first 7 d; feed intake was restricted for half the replicate pens during the periods of 7 to 14 d based on 7-d BW. From 14 to 63 d birds were given access to ad libitum feed intake. Live performance was examined at 14, 21, 42, and 63 d. Carcass characteristics were examined at 63 d. Body weight gain was significantly reduced at all ages as a result of early feed restriction. Feed intake following restriction was significantly lower at all ages. However, feed conversion was significantly improved at all ages after the restriction period for the restricted group compared with the control group fed ad libitum. Similarly, caloric efficiency was significantly improved by restriction. Mortality following feed restriction was significantly lower. Dressing percentage and quantitative breast yield were significantly reduced by restriction. Overall percentage breast yield was not affected. Abdominal fat, expressed either as a percentage of carcass or absolute weight, was not significantly affected by early feed restriction.