Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC 29634, USA.
USDA-ARS Forage Production Research Unit, Lexington, KY 40506, USA.
Toxins (Basel). 2021 Mar 9;13(3):195. doi: 10.3390/toxins13030195.
Grazing endophyte-infected, toxic tall fescue reduces cow/calf production; therefore, this study examines alternate strategies such as use of novel endophyte fescue varieties during late gestation and early lactation or genetic selection of resistant cows. Pregnant cows (n = 75) were randomly assigned to fescue endophyte type: 1) endophyte-infected ergot alkaloid producing tall fescue (E+) or 2) novel endophyte-infected, non-toxic tall fescue (NOV) within maternal (A|A, n = 38 and G|G, n = 37) genotype to examine changes in cow/calf performance and milk production during late gestation and early lactation. Grazing E+ fescue pastures during late gestation reduced cow body weight gain but did not alter calf birth weight compared to NOV. Milk production and calf ADG during the first 30 day of lactation were lower for E+ than NOV. The calving rate was reduced, but not calving interval for E+ cows. The adjusted 205-day weight of calves was lower in those grazing E+ with their dams compared to NOV. There were no interactions between genotype and fescue endophyte type indicating that genotype was not associated with response to E+ fescue in this study. Overall, grazing NOV tall fescue pastures rather than E+ during critical stages of production improved cow gain during late gestation, calving rate, early milk production and calf growth.
放牧内生真菌感染的有毒高羊茅会降低奶牛/小牛的产量；因此，本研究探讨了替代策略，如在妊娠后期和泌乳早期使用新型内生真菌羊茅品种或对具有抗性的奶牛进行基因选择。将怀孕的奶牛（n = 75）随机分配到内生真菌类型：1）内生真菌感染麦角生物碱产生的高羊茅（E+）或 2）新型内生真菌感染的无毒高羊茅（NOV），内生母本（A|A，n = 38 和 G|G，n = 37）基因型，以检查妊娠后期和泌乳早期奶牛/小牛性能和产奶量的变化。与 NOV 相比，妊娠后期放牧 E+羊茅草地会降低奶牛体重增加，但不会改变小牛出生体重。与 NOV 相比，E+的产奶量和小牛的 ADG 在泌乳的前 30 天较低。E+奶牛的产犊率降低，但产犊间隔没有改变。与 NOV 相比，那些与母亲一起放牧 E+的小牛的 205 天调整体重较低。基因型和内生真菌类型之间没有相互作用，这表明在本研究中，基因型与对 E+羊茅的反应无关。总的来说，在生产的关键阶段放牧 NOV 高羊茅草地而不是 E+可以提高奶牛妊娠后期的增重、产犊率、早期产奶量和小牛生长。
