Abstract
Two corn-soy rations formulated to provide normal ME (2,890 kcal/kg) or reduced ME (2,805 kcal/kg) were combined in a factorial arrangement with or without enzyme (Avizyme 1500) supplementation (ES). These rations were fed for a 15-wk period to 2 strains of Single Comb White Leghorn hens (SCWL) [Babcock B-300 (B) and Hy-Line W-36 (H)] beginning at 25 wk of age.
Overall feed intake was significantly affected only by strain not by dietary ME level or ES. Energy level of ration and strain of hen had a significant effect on feed efficiency: a 9-point difference in feed conversion favoring Hy-Line W-36 and a 5-point difference favoring the normal dietary ME (2,890 kcal/kg). Enzyme supplementation significantly affected egg production (EP) differently in each strain. We observed increased EP by Hy-Line W-36 hens on the reduced ME diet with ES, but in the Babcock B-300 hens only those on the normal ME diets with ES had increased EP. Egg weight showed a significant interaction effect of,dietary ME supplementation and strain such that the Babcock B-300 hens laid eggs of greater weight when fed normal ME diets compared with eggs from the Hy-Line W-36, which were heavier from hens on the reduced ME diet. Percentage of yolk increased among hens fed the reduced ME diets; yolk percentage of Babcock B-300 eggs was greater than that of eggs from Hy-Line W-36. Roche Color fan score decreased in eggs from hens on the reduced ME diet.
Enzyme supplementation had a significant positive effect on protein and calcium retention but no effect on AME or gut content viscosity. Enzyme supplementation also negatively affected phosphorus retention.