Document Type

Dissertation - University Access Only

Award Date

2008

Degree Name

Doctor of Philosophy (PhD)

Department / School

Animal Science

Abstract

Research studies have demonstrated that wet distillers grain (WDG) is an excellent source of protein and energy to lactating dairy cows. When fed at concentrations below 20% ration OM for short periods, it can support similar milk production and composition. The main hypothesis for this study is that when fed over a long period of time, the high fat content, highly digestible fiber and low starch concentration in distillers grain can improve lactation performance, provide energy to reduce adipose tissue and protein mobilization, metabolic disorders, and acidosis in lactating cows. In experiment 1, WDG was fed at 15% of ration over an entire lactation period and the control experimental diet had soybean meal, soyplus, soybean hulls, and extruded soybean seeds in place of WDG. The diets were formulated to have equal CP, ether extract and net energy of lactation. Cows fed WDG had similar dry matter intake and milk yield, a tendency for greater energy corrected milk, feed efficiency and protein percent and significantly greater protein yield compared with cows fed a control diet. The conditions in the rumen for cows fed WDG and control diets were similar as depicted by volatile fatty acid concentrations and ruminal pH and acetate:propionate ratio. In experiment 2, when WDG was fed during the close up and early lactation period, it supported similar dry matter intake. Milk yield and milk composition was similar except for protein percent which was greater for cows fed WDG. There was no difference in concentrations of glucose, blood urea nitrogen, cholesterol, non esterified fatty acids and betahydroxybutyrate prepartum. Postpartum, cows fed WDG had greater plasma glucose concentrations while the cows fed control diet had increased plasma NEFA, BHBA and BUN concentrations. Holstein cows had greater plasma NEFA concentrations than did Brown Swiss. In conclusion, feeding WDG at 15% ration OM led to similar milk and component yields, rumen volatile fatty acids and milk fatty acids composition. Feeding WDG also increased glucose and decreased BHBA, NEFA and BUN concentrations during early postpartum. This possibly lead to a reduction in metabolic disorders.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds

Distillers feeds

Lactation

Proteins in animal nutrition

Format

application/pdf

Number of Pages

118

Publisher

South Dakota State University

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