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R. K. Poole, T. L. Devine, J. C. Mackey, M. H. Poore, D. H. Poole, 040 Ergot Alkaloids from Endophyte-Infected Tall Fescue Alters Ovarian Follicle Growth and Development in Beef Heifers, Journal of Animal Science, Volume 95, Issue suppl_1, December 2016, Pages 19–20, https://doi.org/10.2527/ssasas2017.040
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Abstract
Fescue toxicosis is a disease common in cattle grazing tall fescue [Lolium arundinaceum (Schreb.) Darbysh]. containing an endophytic fungus (Epichloë coenophiala) that produces ergot alkaloids. Previous research from our lab demonstrated that chronic exposure of ergot alkaloids reduced ovarian and uterine blood flow, which could alter ovarian function. Therefore, the objective of this study was to determine if ergot alkaloids from endophyte-infected tall fescue reduces follicle numbers, or suppresses follicular development resulting in poor embryo growth. Angus × Senepol heifers (n = 30) were blocked by weight and genotype [Slick (S) or Normal (N)] were placed in Calan gates then randomly assigned to receive either endophyte-infected fescue seed (EI) or non-infected fescue seed (EF; control) for 63d. Weekly measurements were collected to monitor physiological responses during exposure to ergot alkaloids. Following 30d of exposure to ergot alkaloids, heifers were synchronized and inseminated to examine reproductive measurements, including daily follicle mapping, AI pregnancy rate, and embryo development. Data were analyzed using repeated measures in the PROC MIXED procedure of SAS. ADG was decreased in EI-N heifers (0.48 kg/d) compared to other heifer groups (P < 0.05; 0.63, 0.62, 0.58 kg/d for EI-S, EF-N, and EF-S, respectively). BCS were greater for EF-S, EI-N and EI-S (5.6, 5.6 and 5.7, respectively) compared to EI-N (5.5; P < 0.05). Hair shedding scores were lower for EF-S and EI-S (1.5 and 2.2, respectively) compared to EF-N and EI-N (2.5 and 2.6, respectively; P < 0.05). The number of recruited (2-4mm) follicles was significantly greater in EI-N heifers (13.7) and significantly lower in EF-N heifers (10.6) compared to other heifer groups (P < 0.05; 11.1, 12.2 follicles for EI-S, and EF-S, respectively). No differences were observed (P > 0.05) in the number of selected (5 to 8mm) follicles. Whereas, the number of dominant (> 9mm) follicles was reduced in EI-N heifers (0.52) compared to other heifer groups (P < 0.05; 0.85, 0.87, 0.93 follicles for EI-S, EF-N, and EF-S, respectively). AI pregnancy rates were decreased in EI-N heifers (0%) compared to other heifer groups (P < 0.05; 86, 50, 43% for EI-S, EF-N, and EF-S, respectively). No differences were observed in early embryo growth and development. Based on these data, ergot alkaloids from endophyte-infected tall fescue alter ovarian follicular development, specifically during the selection to dominant stage, potentially contributing to the poor reproductive performance in infected cattle. However, the slick hair genotype appears to aid in offsetting the physiological symptoms associated with fescue toxicosis, resulting in improved pregnancy rates.
