Effect of Endophyte-Infected Tall Fescue Toxins on Growth Performance and the Microbial Community in the Rumen and Feces in Pregnant Ewes

Fifty pregnant Katahdin ewes grazed pastures with high (HE) and moderate (MI) levels of Neotyphodium coenophialum-infected tall fescue between February 1 and May 24 to determine the impacts of tall fescue toxins on body weight (BW), body condition scores, FAMACHA scores, fecal egg counts (FEC), and serum Cu, Zn, prolactin, and non-esterified fatty acids (NEFA). Within those 50 ewes, 15 were selected randomly for fecal and rumen sampling to assess the impacts of HE and MI on the microbiome community. Total bacterial DNA was extracted from rumen and fecal samples, and alpha and beta diversities were used to relate microbiome data diversity with forage treatments and physical and physiological measurements. Most of the ewe physical and physiological measurements were not affected by endophyte levels. However, body weight changes (d 51 to d 115) and NEFA changes (d 51 to d 115) were greater in MI than HE. The HE group had greater observed ruminal OTUs, Shannon, Chao, and beta diversities at d 115 than MI. Members of Bacteroidetes_Prevotella ruminal bacteria OTUs were correlated with BW changes, prolactin concentrations, NEFA changes, and FEC. Also on d 115, there was an increased abundance from Firmicutes in HE vs. MI (60% vs. 53 %, respectively). The HE group had greater observed fecal OTUs, Shannon, and Chao, on d 51 than MI, but beta diversities did not differ between HE and MI during the study. Members of Actinobacteria_Coriobacteriaceae_unclassified fecal OTUs were correlated with BW changes, prolactin concentrations, NEFA changes, and FEC. At the end of the study, there was decreased abundance from Bacteroidetes in MI and HE (52.9 % and 49.3 %, respectively). Shifting of rumen or fecal bacteria populations that occurred could be a direct effect of the ergot alkaloids or indirect effects of toxins on intake or digestibility that subsequently impacted the bacterial populations. It is also possible that the bacteria that detoxify ergot alkaloids are minor species that have yet to be classified. Further research in the rumen or fecal microbial and their changes in responses to grazing endophyte-infected fescue needs to be considered to identify bacteria responsible for the detoxification