Consumption of Toxic Fescue Impairs Bull Reproductive Parameters

Abstract

Consumption of toxic endophytic tall fescue grass is associated with reduced fertility rates in livestock. In this study, Angus bulls were fed a control diet (n = 3) or toxic fescue diet (n = 3) for 60 d. Semen was collected by electro-ejaculation twice weekly and evaluated for spermatozoal motility, morphology, and concentration. Scrotal temperatures, scrotal circumferences, and rectal temperatures were measured prior to each collection. Significant differences were observed for scrotal temperatures (P<0.001), scrotal circumference (P<0.01), and spermatozoa concentration (P<0.05). Scrotal temperatures were greater, scrotal circumferences were smaller, and spermatozoal concentrations were greater in the collections from bulls fed the fescue diet. Neither sperm motility nor morphology were affected by dietary treatment; however, there appeared to be a detrimental effect associated with treatment diet by day on motility during the last 2 wk of the trial (P=0.08). These results indicate that bulls fed toxic endophyte-infected (EI) fescue may experience impaired reproductive capabilities.