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Evaluating the Efficacy of Exogenous Enzymes on Nutrient Digestibility and Broiler Performance
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The objective of this research was to evaluate the efficacy of exogenous enzymes on nutrient digestibility and broiler performance. Experiment one evaluated the addition of a corn-screenings in low-energy corn-soybean meal diets with and without NSPase supplementation. The addition of corn-screenings hindered growth performance with reductions in feed consumption, body weight, and an increase in FCR. Removing energy in the diet increased FCR throughout the study. The inclusion of NSPase reduced FCR throughout the trial compared to the control. These results demonstrate the effectiveness of NSPase inclusion on growth performance in reduced energy diets containing lower quality feed ingredients. Experiment two consisted of three studies evaluating the inclusion of a cocktail NSPase in low-energy diets on broiler growth performance and processing. Each study consisted of three dietary treatments including a positive control (PC), negative control (NC) with a 132 kcal/kg reduction in energy, and NC with NSPase supplementation. Broiler performance was improved in each study with the inclusion of a cocktail NSPase increasing body weight and improving FCR. Furthermore, supplementing NSPase increased multiple processing parameters when compared to the reduced-energy diet. The results of this experiment confirm the ability of exogenous enzymes to improve broiler performance and processing parameters when included in reduced-energy diets. Experiment three determined the impact of increasing levels of phytase inclusion on nutrient digestibility, bone mineralization, and broiler performance. Reducing phosphorus levels in the NC negatively influenced bone mineralization, nutrient digestibility, and growth performance throughout the experiment. The supplementation of increasing doses of phytase linearly and quadratically improved all parameters evaluated when included in low-phosphorus broiler diets. Additionally, the supplementation of super-doses (> 1,500 FTU/kg) of phytase yielded more pronounced benefits when compared to phytase included at conventional levels justifying the potential use of greater concentrations of phytase in broiler diets. The results of this experiment suggest that greater levels of phytase may elicit a more pronounced improvement on nutrient digestibility, bone mineralization, and growth performance compared to conventional doses of phytase.
Walters, Hunter Grant (2019). Evaluating the Efficacy of Exogenous Enzymes on Nutrient Digestibility and Broiler Performance. Doctoral dissertation, Texas A&M University. Available electronically from