Ergot alkaloid exposure during gestation alters: I. Maternal characteristics and placental development

Authors: BRITT, JESSI - Clemson University; GREENE, MASLYN - Clemson University; BRIDGES, JR., W - Clemson University; Klotz, James; Aiken, Glen; ANDRAE, JOHN - Clemson University; PRATT, SCOTT - Clemson University; LONG, NATHAN - Clemson University; SCHRICK, F. NEAL - University Of Tennessee; STRICKLAND, JAMES - Clemson University; WILBANKS, S - Clemson University; MILLER, JR., MARKUS - Clemson University; KOCH, B - Clemson University; DUCKETT, SUSAN - Clemson University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/11/2019
Publication Date: 2/19/2019
Citation: Britt, J.L., Greene, M.A., Bridges, Jr., W.C., Klotz, J.L., Aiken, G.E., Andrae, J.G., Pratt, S.L., Long, N.M., Schrick, F., Strickland, J.R., Wilbanks, S.A., Miller, Jr., M.F., Koch, B.M., Duckett, S.K. 2019. Ergot alkaloid exposure during gestation alters: I. Maternal characteristics and placental development. Journal of Animal Science. 97(4):1874-1890. https://doi.org/10.1093/jas/skz068.
DOI: https://doi.org/10.1093/jas/skz068

Interpretive Summary: Reduced birth weights have been reported in offspring born to dams exposed to endophyte-infected tall fescue that contains ergot alkaloids during gestation. Little research has examined how timing of ergot alkaloid exposure alters placental function and fetal development during gestation. The objective of this study was to assess how feeding tall fescue seed containing ergot alkaloids during mid and/or late gestation alters placental development and fetal growth. A study was conducted where twin pregnant ewes were fed a diet with or without ergot alkaloids for day 35 to day 133 of gestation or switched treatments on day 86. Fescue toxicosis was successfully induced in the ewes receiving ergot alkaloids through consumption of endophyte-infected tall fescue seed. Exposure to ergot alkaloids in the first half of gestation (d 35 to d 86) had little to no effect on placental development and fetal growth, where as ewes that were exposed to ergot alkaloids in the second half of gestation (d 86 to d 133) did have reduced placental and fetal weights. The stunted placental development is likely due to the vasoconstrictive effects of the ergot alkaloids and this limited fetal growth. This produced smaller fetuses with lighter muscle and organ weights. These results clearly demonstrate the negative effects ergot alkaloids found in tall fescue have on placental development and fetal growth during late gestation. This research provides essential information to livestock producers that clearly defines the critical period of gestation where ergot alkaloid exposure by pregnant grazing livestock must be avoided to maximize productivity.

Technical Abstract: Tall fescue [Lolium arundinaceum (Scheyreb.) Darbysh] is the primary cool season forage grass in the Southeastern U.S. due to its drought tolerance, disease resistance, superior growth, and overall hardiness. The majority of tall fescue contains an endophytic fungus (Epichloe coenophiala), which produces ergot alkaloids. Ingestion of ergot alkaloids induces fescue toxicosis, a disease marked by decreased weight gain, reproductive problems, reduced vascular function, and reduced birthweights. The objective of this study was to assess how exposure to ergot alkaloids during two stages of gestation alters placental development and fetal growth. Thirty-six Suffolk ewes estimated to be carrying twins were randomly assigned to one of two dietary treatments (endophyte-infected (E+) tall fescue seed or endophyte-free (E-) tall fescue seed) fed during two stages of gestation (MID, d 35 – 85 or LATE, d 86 – 133) in a 2 x 2 factorial. Terminal surgeries were conducted on d 133 of gestation and maternal, placental, and fetal data were collected. Ewes receiving E+ treatment during LATE gestation had lighter (P = 0.002) cotyledon weights and lighter (P = 0.001) caruncle weights compared to ewes receiving E- treatment. Additionally, placentome morphology was negatively affected with ewes on E+ treatment during LATE gestation exhibiting lighter (P = 0.024 and P = 0.035, respectively) type B cotyledon and caruncle weights. Ewes on E+ fescue during MID and LATE gestation tended (P < 0.10) to have lower number of type B and higher number of type A placentomes. Fetuses from dams fed E+ fescue seed during LATE gestation had reduced empty body weight (EBW; P = 0.001), organ weights (P < 0.05), and individual muscle weights (P < 0.05); however when normalized to EBW, fetal muscle and organ weights were not different (P > 0.05) by dam treatment. Fetuses from dams fed E+ fescue during LATE gestation had greater (P = 0.019) brain weight as a percent of EBW compared to E- fetuses, which is indicative of IUGR. The current research suggests that ergot alkaloid exposure during LATE gestation negatively impacts placental development and limits the capacity for fetal growth.