Effects of dietary energy concentration on production of broiler chickens

Abstract

Eight least-cost diets with a determined range of metabolizable energy (ME) concentrations from 9.3 to 14.3 MJ kg-1 were formulated. Each diet was offered for about 12 weeks to two pens of about 100 broilers of each sex. Observations on feed consumption, liveweight and mortality were made weekly for each pen. Dressing percentages were recorded for samples of ten birds from each pen at two different Iiveweights. As ME concentration of the diets increased, birds grew faster and required less food, in terms of both total weight and total energy, to reach specified liveweights, although these effects were not marked when the dietary ME concentration was above 13.5 MJ kg-1. Feed conversion was less efficient at the same ME concentration when birds of each sex were taken to higher liveweights. Dressing percentage increased with increases in dietary ME concentration for males, but for females it tended to decline at the highest energy concentrations. Mortality was the same (2 per cent) on all diets.