Influence of genotype, sex and age of chickens on metabolisable energy of poultry feeds

Abstract

The influence of genotype, age and sex on apparent metabolisable energy (AME) and on nitrogen-corrected AME (AMEn) was studied using male and female chickens of two different genotypes (RIR and Cornish lines) at 4 and 8 weeks of age. The experiment was carried out for the purposes of better understanding the effect of age on dietary AME and AMEn of high protein-low energy (LEHP) and low protein-high energy (HELP) diets. These types of diets are used in the determination of the AMEn content of feed ingredients. The influence of age on metabolisable energy values obtained for the feed ingredients was not consistent; thus, AME and AMEn values obtained for corn were not significantly different (P>0.05) at 4 and 8 weeks of age, but with respect to fish meal significant difference (P>0.05) was ascertained between the ages in both genotypes. Hie AME and AMEn values calculated for corn at both ages were the same for both genotypes and both sexes. Also, the level of corn intake had no influence on metabolisable energy at these two ages. However, variation in fish meal intake and its metabolisable energy content was dependent on the growing period. AME and AMEn values obtained for the LEHP diet, but not for the HELP diet, increased significantly between 4 and 8 weeks of age, representing a significant interaction between age and experimental diet. The AME and AMEn were significantly lower at four weeks than at eight weeks of age for LEHP, in contrast with the HELP diet.