Impact of Xylanase and Other Exogenous Enzymes, Fed Individually and in Combination, with Direct Fed Microbials on Broiler Growth Performance
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The aim of this research program was to evaluate the inclusion of exogenous enzymes, individually and in combination, with direct fed microbial products on broiler growth performance and nutrient digestibility over a series of experiments. Inclusion of a thermotolerant xylanase product derived from Pichia pastoris significantly improved feed efficiency in broilers fed a corn-based diet with DDGS. When xylanase was supplemented a 10,000, 20,000, and 40,000 units, a clear dose response was observed with 20,000 unit supplementation showing consistent improvements in body weight (BW), ileal digestible energy (IDE), and feed conversion ratio (FCR) leading to improved feed efficiency and overall broiler performance. Supplementation of a Bacillus based direct fed microbial (DFM) significantly increased broiler performance compared to the non-supplemented control through improvements in feed consumption (FC), BW, and body weight gain (BWG) which were comparable to antibiotic growth promoter (AGP) inclusion. Furthermore, inclusion of high levels (10, 15, and 20%) of distiller’s dried grains with solubles (DDGS) significantly increased FCR resulting in reduced broiler performance. At the conclusion of the trial, increasing inclusion levels of DDGS did not impact DFM efficacy. However, DFM inclusion improved feed efficiency in DDGS containing diets regardless of level. The inclusion of a feed additive containing a combination of xylanase, amylase, and protease (XAP) + DFM decreased finisher phase FCR as well as cumulative d 42 FCR and produced similar results to AGP inclusion. Foot pad lesion score was also significantly improved with XAP + DFM inclusion to levels similar with AGP inclusion. The inclusion XAP + DFM also improved caloric efficiency by reducing the amount of energy (kcal) needed to produce one kg of body weight gain. Finally, the inclusion of XAP + DFM resulted in improved broiler performance regardless of the presence or absence of AGP. In totality, this research program confirms that the addition of xylanase is an effective way to increased nutrient digestibility and that combining effective exogenous enzymes with DFM can be an effective alternative to AGP inclusion. Additionally, the performance benefits of XAP + DFM inclusion can be realized regardless of the presence or absence of AGP.
Flores, Cody Andrew (2017). Impact of Xylanase and Other Exogenous Enzymes, Fed Individually and in Combination, with Direct Fed Microbials on Broiler Growth Performance. Doctoral dissertation, Texas A & M University. Available electronically from