Utilization of metabolizable energy by young broilers and birds of intermediate growth rate

摘要: An experiment was conducted to study the utilization of ME by 3 strains birds with different growth rates: commercial broilers, Plymouth Barred Rocks, and Leghorns. Birds were fed a diet providing 3,100 kcal ME/kg 20% CP from 0 42 d. nitrogen balance determined 10 15, 23 28, 37 Energy retained (ER) as fat (ERF) protein (ERP) derived body analyses for each period group birds. ERF ERP obtained difference in values at end their respective predicted based on BW beginning period. ER, ERF, per unit metabolic significantly broilers vs. other 2 all periods (P < 0.001). Heat production ER increased 0.01) groups. There significant decrease HP 0.001) over time no change or time. Age appeared have effect ERF/ME regardless strain. Estimation maintenance requirements function BW0.75 BW0.60 showed that kilogram are 8% lower compared estimates BW0.60. It seems energy has been underestimated younger smaller implies greater apparent efficiency growth. Because intake represents large portion intake, results this could be considered calculation growing broilers.