Doctoral Dissertations

Date of Award

8-1991

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Animal Science

Major Professor

Karl M. Barth

Committee Members

P. Michael Davidson, Robert A. McLean, James D. Quigley III, Kelly R. Robbins

Abstract

Study 1. A laboratory-scale experiment with 75-kg steel drums was conducted using sorbic acid (SA), an amylase-sterilant (AS) or both (SA+AS) as silage additives for whole-plant corn, to determine type of fermentation and change in nutrient composition over time due to treatments. Addition of SA, AS or SA+AS increased concentrations of water-soluble carbohydrates (WSC) by 60.3, 17.4 or 50.1%, respectively. Treatment with SA inhibited formation of butyric acid, and lowered ammonia-N and ethanol concentrations in silage by 6.4 and 34.2% respectively (P< .02). Use of AS reduced butyric acid concentration, but increased ammonia-N and ethanol content in silage by 6.8 and 33.1%, respectively (P< .10).

Study 2. Using the aforementioned silages, a digestion and nitrogen balance trial and a rumen fermentation experiment measuring in-vitro gas production and microbial protein synthesis were conducted. In-vitro gas production was increased twofold in sheep fed SA- or AS-treated silages (P< .10). Microbial protein synthesis with SA, AS or SA+AS treatment was increased by 125, 133 (P< .10) and 61%, respectively. Digestibility and nitrogen utilization were not affected by treatments.

Study 3. A fermentation time study with 8-kg plastic buckets using α-amylase, α- and β-amylases or α-, β-amylases and sulfur-salts (AS) as silage additives, and a growth trial with beef heifers were conducted to identify the cause for increased animal performance with AS-treated silages. After 28 days of ensiling, all amylase-treated silages retained 41 to 60% higher concentrations of WSC (P< .10), and produced more lactic acid (P< .10) than untreated silage. Presence of fungi was reduced in two of the amylase-treated silages (1.10 to 1.17 log; P< .10). Dry matter recovery of amylase-treated corn silages was markedly increased (6.3 to 10.7%, P< .10). Beef heifers fed amylase-treated corn silages had 5.3 to 12.1% increased ADG. Results suggest that addition of SA and AS shows potential for improving silage quality, nutrient preservation and ultimately, animal productivity.

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