The Effect of Different Dietary Energy Regimens on the Performance of Two Commercial Chicken Broiler Genotypes Reared to Roaster Weight

An experiment was conducted involving two commercial male Shaver genotypes (1200 of each) to ascertain the optimal level of dietary energy for roasters at each stage of production using a three-stage (starter, grower, finisher) feeding system of 16-20-16% dietary protein, respectively. Of the regimens examined, a starter-grower-finisher regimen with 3000, 3100, 3200 kcal/kg metabolizable energy resulted in the heaviest body weights and best feed conversion and monetary returns. Detailed examination of the leg bones of approximately one-half the population showed the true incidence of leg abnormalities in this type of bird to range between 37 and 41%, depending on genotype. Although the incidence of slipped tendons tended to increase (significant for the highest energy regimen) with increasing levels of dietary energy, the incidence of total leg abnormalities (all types) was not altered significantly by dietary energy level per se.