Date of Award

5-2026

Document Type

Thesis

Degree Name

Master of Agriculture (MAgr)

Department

Animal and Veterinary Sciences

Committee Chair/Advisor

Susan Duckett

Committee Member

James Klotz

Committee Member

Matias Aguerre

Abstract

Tall fescue (Lolium arundinaceum) infected with an endophyte produce ergot alkaloids such as ergovaline that contribute to fescue toxicosis and reduce livestock performance. Because ergot alkaloids cause vasoconstriction, consumption of toxic fescue may reduce uteroplacental blood flow and restrict fetal growth. The objective of this study was to determine if supplementation with 5-hydroxtryptophan (5-HTP) could alter fetal liver development, gene expression, and metabolomic profiles in pregnant ewes consuming toxic tall fescue during late gestation.

Suffolk ewes (n=27) carrying twin fetuses were assigned to 1 of 3 treatments from gestational day 86 to 111: control (CON), toxic tall fescue seed (TF), or toxic tall fescue seed plus 5-HTP (TF+5-HTP). On gd 112, necropsy was completed and fetal lambs were collected. Fetal body and liver weights were recorded, and fetal liver tissue was collected for RNA extraction, quantitative PCR validation, and untargeted metabolomic profiling.

Compared to CON, fetal body weight was reduced by 15.6% in TF, whereas TF+5-HTP was 6.2% lower than CON but did not differ from either CON or TF. Liver weight was reduced by 12.6% in TF+5-HTP and 18.2% in TF compared to CON. Quantitative PCR detected treatment effects for IL6, CYP2E1, and IGF1. IL6 expression was downregulated in TF+5-HTP compared with CON, while TF did not differ from either group. CYP2E1 expression was upregulated in TF compared to CON and TF+5-HTP, while TF+5-HTP did not differ from CON. IGF1 expression was upregulated in TF compared to CON, while TF+5-HTP did not differ from either group. Untargeted metabolomic profiling analysis showed the greatest number of differential metabolites in TF compared to CON. Enriched pathways included biosynthesis of amino acids, cysteine and methionine metabolism, lysine degradation, phenylalanine metabolism, glutathione metabolism, fatty acid biosynthesis, and ABC transporters. In TF+5-HTP compared with TF, there were enriched tryptophan-related pathways, D-amino acid metabolism, aminoacyl-tRNA biosynthesis, and glycine, serine, and threonine metabolism.

These results indicate that maternal consumption of toxic tall fescue during late gestation altered fetal growth, liver gene expression, and fetal liver metabolic pathways. Supplementation with 5-HTP at 2.5 mg/kg changed some inflammatory and metabolic responses, but it did not completely prevent the effect of toxic fescue during late gestation.

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