Year of Publication

2017

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department/School/Program

Animal and Food Sciences

First Advisor

Dr. David L. Harmon

Abstract

Fescue toxicosis is problematic for ruminant livestock, causing weight loss and low productivity when fed endophyte-infected forages. Complete underlying mechanisms of toxicosis are unknown therefore; the objective of the study was to determine if ruminally dosed ergot alkaloids impact rumen motility. Cannulated steers were pair-fed a forage diet and ruminally dosed with endophyte-free (E-) or endophyte-infected (E+) tall fescue seed. An 8-h period of rumen motility collection began 4-h after feeding by monitoring pressure change via a wireless telemetry and transducer system. In experiment 1, steers were paired by weight and assigned to E- or E+ treatment. Overall, E+ steers had more frequent contractions. On d 7 - 9, both treatments had lower frequencies and E- steers had greater amplitude of contractions, which corresponded with decreased DM intake. In experiment 2 steers remained in pair, but switched treatment. During the 57 d E+ steers received titrated levels of ergovaline + ergovalinine. There was no difference between treatments for frequency or amplitude of contractions, but increasing dosage, decreased frequency (d 1 - 44) and amplitude, coinciding with lower DM intakes. Alteration in rumen motility associated with changes in intake may be responsible for the decreased productivity in ruminants consuming E+ forages.

Digital Object Identifier (DOI)

https://doi.org/10.13023/ETD.2017.396

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