Nutritional homeostatic capacity of a three-breed cross in poultry and associated effects of genotypes at the pea comb and endogenous viral element 1 loci.

The effect of varying combinations of dietary CP, at 16, 18, and 20%, with ME, at 2,900 and 3,100 kcal ME/kg, on BW and feed conversion (FC) at 2 to 6 wk of age for a three-breed cross was evaluated. Additionally, effect of genotypes at the pea comb (P) and endogenous viral element 1 (ev1) loci on dietary treatments were evaluated. Average weekly feed intake per bird varied from 25.6 to 32.6 g for birds on 16% CP, 3,100 kcal ME/kg and 20% CP, 2,900 kcal ME/kg diets, respectively. Weekly BW and FC were highest for birds on a combination of 20% CP and 3,100 kcal ME/kg diet. On 18% CP and 3,100 kcal/ME diet, males with pea comb had significantly higher BW than those with a single comb. At the ev1 locus, differences among genotypes were significant only for BW of females on a diet consisting of 20% CP and 2,900 kcal ME/kg. Pooled data from the dietary treatments revealed that males with pea comb had significantly higher BW than males with single comb at 3 to 6 wk of age. Birds heterozygous at the ev1 locus had higher BW than those homozygous at this locus. Results of the current studies provide information necessary to develop the optimal protein and energy combination for BW and FC for a three-breed cross involving Araucona, White Leghorn, and Rhode Island Red. These studies also provide additional evidence of the possible effects of the P locus and a gene linked to it, ev1, on production traits in chickens.