Evaluation of a novel endophyte-infected tall fescue cultivar as a safe forage for pregnant mare

Fescue toxicosis is a condition that afflicts livestock grazing endophyte-infected tall fescue and is particularly detrimental to pregnant mares. A two year evaluation study of a novel endophtye-infected cultivar, PDF 584, did not induce fescue toxicosis in late-term pregnant mares. All mares delivered viable foals except in E+ group which had two viable foals, one stillborn-dystocia and one compromised foal which was euthanized at 72 h pp. Serum P4 concentrations were similar among PDF 584, NE+, and E- mares (p>0.05). Foal BW and foal/placental weight ratios were similar for PDF 584, NE+, and E- (p>0.05). Foal serum P4 was similar on 1 d and 2 d in all groups, but was lower (p = 0.049) in the PDF 584group than the E- foals on day 0. Neutrophil/lymphocyte ratios were similar (∼5:1) in all foals on d 0 and 2. IgG values were similar (p>0.05) among PDF 584, NE+, and E-.;Key words: novel endophyte-infected fescue, mares, fescue toxicosis.