Evaluation of Nutritional Strategies Focused on Exogenous Enzymes Aimed at Maximizing Broiler Performance and Nutrient Utilization
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The objective of this research was to quantify improvements in nutrient digestibility and performance using multiple exogenous enzymes which target different substrates in diets varying in nutrient density. Experiment one consisted of three control diets varying in dietary energy with the supplementation of xylanase at two inclusion rates. Reducing the dietary energy level negatively influenced feed conversion ratio (FCR) and decreased the fat pad weight of broilers in the reduced energy diet compared to the positive control. The inclusion of xylanase reduced FCR throughout the trial compared to the control. These results demonstrate the effectiveness of xylanase inclusion in reduced energy diets to improve FCR of broilers. Experiment two evaluated the inclusion of a cocktail NSPase and β-mannanase, separately or intermittently, on broiler growth performance and processing. Broiler performance was improved with the inclusion of a cocktail NSPase and β-mannanase throughout the experiment. When evaluating weight gain from d 22 to 47, the intermittent application of cocktail NSPase and β-mannanase improved weight gain compared to the positive control diet. The results of this experiment confirm the ability of exogenous enzymes to improve the nutritive worth of feed ingredients by enzymatic degradation. Experiment three determined the impact of corn source on broiler performance and nutrient digestibility with or without the inclusion of xylanase. The variability of nutrient profile between corn sources influenced body weight, FCR, and nutrient digestibility throughout the trial. Xylanase inclusion improved FCR in the finisher phase suggesting that the length of time feeding enzymes may be impactful to the final outcome of performance. The results of this experiment indicate the importance of rapid and accurate evaluation of corn nutrient content to maximize observed growth performance. Experiment four evaluated the effects of calcium (Ca) and phosphorus (P) level in a diet containing super-dose (> 3X dose) levels of phytase on male broiler performance and breast meat yield. Calcium and P level influenced broiler performance, tibia ash percent, fecal mineral content, and litter mineral content. These data illustrate the importance of utilizing the correct Ca and P matrix value in diets containing phytase. This research program outlines the importance of adequate understanding of nutritional value of raw ingredients for accurate formulation when utilizing exogenous enzymes.
Lee, Mallori Williams (2019). Evaluation of Nutritional Strategies Focused on Exogenous Enzymes Aimed at Maximizing Broiler Performance and Nutrient Utilization. Doctoral dissertation, Texas A & M University. Available electronically from