Date of Award:

5-2012

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

Jong-Su Eun

Committee

Jong-Su Eun

Committee

Dale R. ZoBell

Committee

Allen J. Young

Committee

Kenneth L. White

Abstract

A series of experiments were conducted to investigate the effects of adding an exogenous proteolytic enzyme (EPE) on growth performance and ruminal fermentation characteristics of beef steers fed growing and finishing diets containing 30% dried distillers grains with solubles (DDGS).

In the first experiment, 48 beef steers were divided into two treatments: DDGS diets with and without EPE. Dry matter intake (DMI) was increased (P = 0.02) by the addition of EPE, but neutral detergent fiber (NDF) digestibility was decreased on the growing phase. For the finishing phase, average daily gain (ADG) and final body weight (BW) tended to increase (P = 0.09, 0.11 respectively)and digestibilities of dry matter (DM), crude protein (CP), NDF and ADF also increased (P = 0.04).

An in vitro experiment was then performed to corroborate results of the in vivo experiment. Diets containing no DDGS (NDT) were added to analyze effects of DDGS and its interaction with EPE. Feeding the DT increased total VFA concentration (P = 0.01) which corresponded with a decreased (P < 0.01) pH compared with the NDT diet (5.8 vs. 6.0) regardless of EPE supplementation. Supplementing EPE tended to increase (P = 0.07) the total VFA concentration in both diets, but only increased digestibility of DM, OM, and NDF when added to the DT diet (P < 0.05), leading to tendencies on TMR × enzyme interaction (P < 0.10).

Addition of the EPE product assessed in this study resulted in positive responses in Exp. 1 and 2 when added to finishing beef steer diets, and thus it is clear that use of protease enzyme products may be more effective in high concentrate diets such as finishing beef steer diets containing DDGS.

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Comments

This work made publicly available electronically on October 19, 2012.

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