Date of Award

5-2018

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Phillip R. Myer

Committee Members

Gary E. Bates, J. Travis Mulliniks, Jason K. Smith

Abstract

The United States is one of the leading producers of beef in the world, producing between 24-27 million pounds each year. To meet the demands of a growing global population, cattle producers are under increased pressure to efficiently produce meat. The climate in the Southeastern United States provides abundant precipitation which cattle producers may utilize for multi-seasonal grazing. While cattle graze on many different forage varieties, tall fescue (Lolium arundinaceum (Darbyshire)) has been cultivated throughout the region as one of the most predominate forages. Tall fescue provides an abundant forage supply for livestock, and can be grazed in both the spring and fall cool season months.Despite the advantages of an ample forage supply, when tall fescue is infected with an endophyte it can be harmful to livestock. This endophyte (Epichloë coenophiala) provides the tall fescue plant with disease resistance and drought tolerance. The endophyte also produces ergot alkaloid compounds which can be harmful to livestock when consumed. Overall reduced reproductive efficiency in males and females as well as reduced growth performance and heat tolerance are several symptoms of the ergot alkaloids. These symptoms are collectively known as tall fescue toxicosis, which can cost the beef cattle industry up to $2 billion in losses each year. In an effort to reduce these effects, the inclusion of legumes such as red clover has proven beneficial. Legumes contain unique compounds known as isoflavones, found in abundance in red clover. The objectives of the present study were to determine the beneficial physiological, behavioral and microbiological influence of red clover isoflavones on beef cattle experiencing tall fescue toxicosis. Isoflavones improved fiber and protein disappearance post ruminal-fermentation compared to control treatments. Isoflavones reduced serum glucose, altered twenty-six ruminal bacterial taxa, but did not affect average daily gain, dry matter intake or serum prolactin levels. Additionally isoflavones did not significantly alter ruminal volatile fatty acid concentrations, pH, or behavioral patterns. The dosage used in the present studies were not sufficient to elucidate the same benefits cattle experience from consuming red clover in a tall fescue pasture, and thus subsequent dosing studies should be conducted.

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