Influence of pelleting on the efficacy of an exogenous enzyme cocktail using broiler performance and metabolism

Abstract

Feed ingredient price has influenced nutritionists to improve diet nutrient availability through the use of exogenous enzyme cocktails (EEC). If EEC are to be added at the mixer before pelleting, then pelleting variables that increase the heat and pressure of feed may denature EEC components, decreasing EEC efficacy. Three experiments were conducted to assess the efficacy of a commercially available EEC postpelleting. The primary pelleting variable manipulated was steam conditioning temperature (71 to 93°C). However, additional variables were modified in subsequent experiments to lessen the potential for high heat and pressure effects on the feed. Dietary treatments consisted of a positive control, a negative control that was reduced in ME and available phosphorus, and a negative control + EEC. Experiment 1 used conditioning temperatures of 82, 88, and 93°C. This experiment indicated no benefit from the EEC on 4- to 21-d broiler chick performance. Experiment 2 used increased mixer-added fat and similar conditioning temperatures relative to experiment 1. Again, no benefit from the EEC was demonstrated on 4- to 21-d chick performance. Experiment 3 used similar diet formulations as experiment 2, a thinner pellet die, conditioning temperatures of 71, 77, and 82°C, and the inclusion of an unconditioned mash treatment. Benefits from the EEC were demonstrated for BW gain and FCR for the unconditioned mash treatment. Trends (P = 0.07) for improved FCR were observed for the EEC pelleted at 82°C. Performance observations in experiment 3 were supported by AMEn data. Overall, on the basis of these studies, future evaluations of EEC efficacy postpelleting should consider several manufacturing variables. © 2012 Poultry Science Association, Inc.