Date of Graduation

12-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Agriculture

Degree Level

Undergraduate

Department

Animal Science

Advisor/Mentor

Dr. Ken Coffey

Committee Member

Dr. Shawna Weimer

Second Committee Member

Dr. Derico Setyabrata

Abstract

Tall fescue infected with endophyte‑producing fungi can induce fescue toxicosis in grazing ruminants, reducing performance and altering forage intake. Isoflavones—such as biochanin A, a major compound in red clover (Trifolium pratense)—have been proposed to mitigate these effects through improved palatability and vascular relaxation. This study examined whether inclusion of ground red clover (GRC)—either directly or combined with hydroxypropyl methylcellulose (HPMC) and polyethylene glycol (PEG)—affected voluntary diet selection in lambs offered toxic fescue.

Thirty‑two lambs were housed individually and assigned randomly to one of four diets: (1) toxic fescue silage (CONT), (2) silage + 5% GRC (RC5), (3) silage + 10% GRC (RC10), or (4) silage + 5% GRC with HPMC and PEG (RC5+) during two experimental periods. Diet refusals were measured daily from each lamb over a 7-d period following a 14-day dietary adaptation, and neutral detergent fiber (NDF) content was analyzed for all feed and refusal. Differences in percent refusal and NDF intake among diets were not statistically significant (p > 0.05). Linear mixed‑model and stepwise regression analyses confirmed that diet refusal was unrelated to red clover inclusion or NDF change, though significant period and animal effects indicated that temporal or cohort factors influenced variation in diet selection.

Therefore, under the tested conditions, GRC supplementation did not significantly alter diet selection. Further research should explore alternate delivery methods or concentrations, greater diet diversity, or other phytoestrogen sources such as biochanin A analogs. Another interesting finding is that reliable diet‑selection data can still be obtained when sheep are fed below the typical 10% refusal threshold.

Keywords

sheep; animal nutrition; toxic fescue; tall fescue; ground red clover; diet selection

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