Kamal Mjoun

Document Type

Dissertation - University Access Only

Award Date

2010

Degree Name

Doctor of Philosophy (PhD)

Department / School

Dairy Science

Abstract

Ethanol production has increased remarkably in the last decade, resulting in large amounts of distillers dried grains with solubles (DDGS) as feedstuffs for livestock animals. In addition, new fractionation and fermentation technologies to maximize ethanol yield have resulted in the availability of a variety of products of different chemical compositions. Recent studies have demonstrated that milk yield and DMI are similar or greater when DOGS were fed between 20 to 30% of the diet compared with soybean based diets. Moreover, milk protein percentage was rarely affected when DOGS were fed up to 20% of the diet. Despite the availability of considerable data supporting that DOGS is a good source of protein, rates of its inclusion are still below potential partly because of concerns about a possible decrease in milk protein synthesis. "New generation" DOGS may be of higher protein quality than commonly thought. In fact, there are indications in the literature that both dietary lysine concentration and amount of AA available for absorption from DOGS are greater than values used in most feed formulation systems. The objectives of our research were to evaluate the quality and feeding of different types of DOGS (conventional and reduced-fat) to dairy cows in different stages of lactation. First, we utilized the arterio-venous technique to assess the utilization of AA in diets containing different concentrations and types of DOGS. Second, we estimated the in vitro intestinal digestibility of CP and AA for different types of distillers grains including conventional, reduced-fat, high protein, and modified wet distillers grains. The results allow us to conclude that DOGS are a highly digestible source of RUP, but a poor source of absorbable Lys. Different DOGS can be effectively fed up to 20% of the diet of early and mid lactation cows without affecting milk yield or components. Arterial Lys concentration decreased with the inclusion of DOGS; however, this decrease was compensated by adaptation in mammary extraction of AA to maintain adequate milk protein synthesis when DOGS was fed up to 20%. This adaptation capacity appears to be inadequate when DOGS is included in the diet at 30% because milk protein percentage decreased. The AA profile and digestibility of RUP may be greater than values currently used in feed formulation and improvements in AA availability may allow for greater inclusion ofDDGS in dairy cow diets.

Keywords: Distillers dried grains with solubles, amino acid, milk protein synthesis, intestinal digestibility.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds

Distillers feeds

Amino acids in animal nutrition

Milk proteins

Format

application/pdf

Number of Pages

187

Publisher

South Dakota State University

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