Influence of level of feed input and procedure on metabolisable and endogenous energy loss with adult cockerels

Abstract

Two experiments were performed to study the relationship between apparent metabolisable energy (AME) and true metabolisable energy (TME) values at different levels of feed intake. Rhode Island Red (RIR) adult cockerels were used in two bioassays, under standard conditions. In the first experiment the birds were starved for 72 hours and then various quantities of corn were fed, the feed ration quantities ranging from 10 to 100 g per bird in 10 g increments, without any regurgitation. There were 6 replicates per treatment. Excreta voided during the 48 hours of the experimental period were collected, their quantity was recorded and samples were assayed for gross energy and nitrogen. In the second assay, after a 4-day adaptation period each bird was starved for 24 hours and during the third experimental period corn was fed ad libitum, in the same rations as those used in the first assay. The birds were then fasted for 24 hours. During the 4 days of the experimental period excreta was collected and frozen for chemical analysis. The main purpose of the experiment was to compare the force feeding procedure for the determination of apparent metabolisable energy, nitrogen correction of AME, true metabolisable energy and N correction of TME with the ad libitum feeding (Conventional Addition Method). The results show that mean metabolisable energy values obtained by the force feeding procedure with high positive intercept were repeatedly higher than those obtained by the ad libitum (CAM). The EEL determined by the force feeding was lower than that given by the ad libitum method; this may be due to the response of the birds to the methodology applied. It was concluded that procedures of feeding do not influence metabolisable energy of corn at different ration levels. Differences among intercepts of the regression line have been reported as evidence that the metabolic plus endogenous energy loss varies at difference corn intake levels. The optimum feed ration quantity proved to be approximately 35 to 40 g for adult Rhode Island Red (RIR) cockerels with both procedures.