@article{newsome_monn_mayberry_poole_young_poore_poole_2018, title={Grazing Novel or Endophyte-Infected Tall Fescue during Mid-Gestation Impacts Cow Performance.}, volume={96}, ISSN={["1525-3163"]}, DOI={10.1093/jas/sky027.025}, abstractNote={Consumption of endophyte-infected tall fescue results in poor reproductive performance. The objective of this study was to examine physiological changes in pregnant cows grazing tall fescue to develop a better understanding of the factors that contribute to the poor reproductive performance attributed to fescue toxicosis. Pregnant Angus and Simmental-Angus cows were blocked by age (2–3, 4–7, and >7 y), BW, and breed; and then randomly assigned to graze either novel (E-; <5% infection rate; n=27) or endophyte-infected tall fescue (E+; 79.5% infection rate; n=27). Weekly BW, BCS, hair coat scores (HCS), and hair shedding scores (HSS) were collected from mid-April through July when ergot alkaloid concentrations are greatest in the forage. Blood samples were collected to measure progesterone concentrations. Forage samples were taken every 2 wks to determine forage quality and composition. Data were analyzed using the MIXED procedure of SAS with repeated measures examined for effects of age, treatment (E- or E+) and time. Statistical significance was determined at P<0.05 and a tendency at 0.05<P<0.10. Pastures consisted of 69% and 67.5% available fescue for the novel and endophyte infected pastures, respectively. Average daily gain tended to be higher in E- cows than E+ (0.16, 0.01 kg/d, respectively; P=0.09). Cows on E- pastures had greater BCS compared to cows on E+ pastures (6.09, 5.77, respectively; P<0.05). Similarly, an age effect was observed with mature (4–7 and >7 y) cows having higher scores when compared to younger cows (6.0, 6.1, and 5.7, respectively; P<0.05). The HCS and HSS were greater in cows on E+ pastures compared to cows on E- pastures (P<0.05). The HSS were greater in the >7 y cows (2.69) compared to other age groups (2.40, 2.51, for 2–3 and 4–7 y, respectively, P<0.05) on E+ pastures, whereas no age differences in HCS were observed in cows on E- pastures. By d21 of the grazing period, cows on E- pastures displayed a greater ability to shed hair compared to cattle on E+ pastures (P<0.0001), which continued throughout the remainder of the grazing period. Progesterone concentrations in E+ cows (3.75 ng/ml) were decreased throughout the grazing period compared to E- cows (6.53 ng/mL, P<0.05). The impact of reduced progesterone concentrations, greater HCS and HSS and tendency for decreased ADG in cows grazing E+ during mid-gestation, compared to cows grazing E-, on calf development remains unknown.}, journal={JOURNAL OF ANIMAL SCIENCE}, author={Newsome, M. A. and Monn, R. E. and Mayberry, K. and Poole, R. K. and Young, Z. and Poore, M. H. and Poole, D. H.}, year={2018}, month={Mar}, pages={13–13} }