Date of Award

5-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Animal and Veterinary Sciences

Committee Member

Dr. Scott L. Pratt, Committee Chair

Committee Member

Dr. John G. Andrae

Committee Member

Dr. William C. Bridges

Abstract

Tall fescue is the most widely used cool-season perennial bunchgrass in the southeastern United States and serves as forage for approximately 8.5 million cattle. Through a mutualistic relationship with the endophyte Epichloë coenophiala, tall fescue is bestowed insect resistance and disease, drought, and grazing tolerance. In spite of these desirable agronomic traits, the endophyte produces ergot alkaloids that are harmful to the physiology of animals consuming tall fescue. Accumulation of ergot alkaloids in animal systems results in a syndrome known as fescue toxicosis. Among other symptoms, reproductive inefficiencies are reported for beef cattle consuming toxic tall fescue. The objectives of this research were to assess the influence of toxic tall fescue consumption on bull sperm by evaluating acrosomal integrity and survival of spermatozoa following cryopreservation. Semen was collected and fixed from bulls that were either fed a ration containing toxic or nontoxic tall fescue seed or grazing toxic or nontoxic tall fescue pasture. Fluorescent-labeled peanut agglutinin was used to evaluate sperm acrosomal integrity. According to our methodologies and data, subtle, if any, differences due to treatment were detected. Semen was also collected, extended, and frozen from bulls grazing toxic or nontoxic tall fescue. Differences due to treatment post-thaw were detected for sperm progressive motility. Significant treatment by day interactions were detected for sperm concentration, motility, total motile sperm per dose, and total progressive motile sperm per dose post-thaw. Our results indicate that acrosomal integrity is not greatly affected by fescue toxicosis, and that grazing toxic tall fescue negatively impacts spermatozoa physiology as measured by survival of sperm following cryopreservation.

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