Abstract
Cattle in some parts of the world graze pastures that consist of tall fescue that may contain ergot alkaloid contamination. Those ergot alkaloids are associated with reduced reproductive rates in cattle. Our objective was to determine if ergot alkaloids [dihydroergotamine (DHET), ergonovine (EN), and ergotamine (ET)] directly affect bovine sperm characteristics. Spermatozoa were collected from mature Angus (n = 2) and Balancer (n = 4) bulls. Within bull, treatments were structured as a 3 × 5 factorial with three alkaloids (DHET, EN, and ET) and five concentrations of each alkaloid (0, 33, 66, 100, or 200 μM). Spermatozoa (25 × 106) were incubated (39˚C) in 1 mL of modified sperm medium. Sperm motility characteristics were evaluated using CASA (Hamiliton Thorne IVOS, Beverly, MA) at 0, 3, and 6 h after initial alkaloid exposure. Initial sperm motility was (69% ± 1.1%) and declined (P = 0.01) to (35% ± 2.6%) at 6 h. Sperm motility decreased (P < 0.05) with increasing concentrations of DHET and ET, but not EN. As concentration of ET or DHET increased all CASA sperm characteristics were altered. The interaction of alkaloid concentration and incubation length affected sperm velocity and head size; exposure to 200 μM of ET or DHET for six hours decreased (P < 0.05) both characteristics. Our results demonstrate that ergot alkaloids (ET and DHET) can directly alter bovine sperm motility and morphology, which adds to our understanding of how ergot alkaloids may hinder cattle reproductive rates.
Highlights
Our results demonstrate that ergot alkaloids (ET and DHET) can directly alter bovine sperm motility and morphology, which adds to our understanding of how ergot alkaloids may hinder cattle reproductive rates
EN did not reduce (P > 0.9) sperm motility or other computer assisted sperm analysis (CASA) characteristics; we reduced the statistical model
Based on our reduced statistical model, CASA sperm characteristics were affected (P < 0.08) by concentration of alkaloids used during incubation (Table 3)
Summary
Cattle consuming tall fescue (Lolium arundinaceum = Schedonorus arundinaceus = Festuca arundinacea) may suffer from numerous physiological conse-. Most tall fescue pastures are infested with wild-type endophyte Epichloë coenophiala (=Neotyphodium coenophialum = Acremonium coenophialum; see [2]). Ergot alkaloids synthesized and released by that endophytic fungus have been associated with toxic effects on livestock (see [3]). They have been linked to depressed reproductive performance [4]. Much of the previous research has focused on reproductive biology of females, such as altered endocrine profiles [5], changes in the estrous cycle [6] and decreased progesterone concentrations [7]
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