ARS | Publication request: Effects of Ergot Alkaloids on Bovine Sperm Motility In Vitro

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 12, 2009
Publication Date: N/A

Interpretive Summary: Ergot alkaloids are the toxic compounds that cause fescue to have detrimental effects on cattle performance. Derivatives of ergot alkaloids decreased human sperm motility and sperm velocity, but minimal research exists on the effects of ergot alkaloids on bull sperm. Scientists from the University of Arkansas and ARS in Booneville, AR, investigated direct effects of ergot alkaloids (ergotamine, dihydroergotamine and ergonovine) on the motility of bull sperm in vitro. Ergotamine and dihydroergotamine inhibited bovine sperm motility; however, ergonovine did not inhibit bovine sperm motility under our incubation conditions. Breeding bulls should not consume toxic fescue prior to or during the breeding to minimize the probability of reduced sperm motility. Reduced sperm motility could have negative effects on the pregnancy rate of the cow herd. Bulls should be fed nontoxic forage and(or) grain diets prior to and during the breeding season to alleviate the detrimental effects of toxic fescue on sperm motility. This information is important to livestock producers and extension personnel.

Technical Abstract: Ergot alkaloids are synthesized by endophyte-infected (Neotyphodium coenophialum) tall fescue (Lolium arundinaceum (Schreb.) S.J. Darbyshire). Our objective was to determine direct effects of ergot alkaloids (ergotamine, dihydroergotamine and ergonovine) on the motility of bovine spermatozoa in vitro. Motile spermatozoa were exposed to alkaloids ranging in concentration from 0 to 100 microM. Assays were conducted in modified sperm-TL (mSPTL) medium at 39°C in moist air without CO2 for 6 h. Sperm motility was evaluated by observing at least 300 spermatozoa per treatment at each interval during incubation. Ergotamine (ET) and dihydroergotamine (DHET) inhibited (P less than 0.05) sperm motility at concentrations greater than 50 microM and 33.3 microM, respectively; ergonovine (EN) did not inhibit sperm motility at the test concentrations. Inhibitory effects of alkaloids on sperm motility were concentration-dependent for both ET and DHET, and time-dependent for DHET incubations. Sperm motility also was inhibited (P less than 0.05) by an interaction of ET and DHET at concentrations greater than or equal to 16.7 microM. Incubation medium pH exacerbated the toxic effects of both ET and DHET; whereas, medium osmolarity only affected the toxic effect of ET on relative sperm motility (P less than 0.05). We conclude that ergot alkaloids can directly interact with spermatozoa, and impair sperm motility.