Endophyte-infected tall fescue affects rumen microbiome in grazing ewes at gestation and lactation

Authors: CHAI, JIANMIN - University Of Arkansas; ALRASHEDI, SALEH - University Of Arkansas; COFFEY, KEN - University Of Arkansas; Burke, Joan; FEYE, KRISTINA - University Of Arkansas; RICKE, STEVEN - University Of Arkansas; PARK, SI HONG - University Of Arkansas; EDWARDS, J - University Of Tennessee; ZHAO, JIANG - University Of Arkansas

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/9/2020
Publication Date: 10/14/2020
Citation: Chai, J., Alrashedi, S., Coffey, K., Burke, J.M., Feye, K., Ricke, S., Park, S., Edwards, J.L., Zhao, J.C. 2020. Endophyte-infected tall fescue affects rumen microbiome in grazing ewes at gestation and lactation. Frontiers in Veterinary Science. 7:1-13. https://doi.org/10.3389/fvets.2020.544707.
DOI: https://doi.org/10.3389/fvets.2020.544707

Interpretive Summary: Tall fescue is a cool-season perennial grass that is widely used as a forage for many livestock species including sheep. An endophyte or fungus in tall fescue produces ergot alkaloids or toxins that enhance plant survival but produce toxicosis in animals, though not all animals become sick. Little is known about mechanisms within the animal that minimize the toxic effects of tall fescue and no one has examined changes in the microbiome of the animal. Scientists at University of Arkansas and USDA, ARS in Booneville, AR discovered variations in microbiome populations among pregnant and lactating sheep grazing moderate or high levels of toxic tall fescue which are thought to be associated with hormone and energy metabolism. This information is important to livestock producers, extension agents, veterinarians, and scientists in many parts of the U.S. and world.

Technical Abstract: Tall fescue (Schedonorus arundinaceus) is a cool-season perennial grass that is widely used as a forage for many livestock species including sheep. An endophyte (Neotyphodium coenophialum) in tall fescue produces ergot alkaloids that enhance plant survival but produce toxicosis in animals. The objective of this study was to investigate the rumen microbiome from gestation and lactation in ewes grazing tall fescue pastures with high (HE) or moderate (ME) levels of endophyte infection, and their relationship with serum parameters. Data were collected at the beginning of the study (d 1), the week before initiation of lambing (d 51), and at the end of the trial (d 115). Rumen microbiomes were evauluated using an Illumina MiSeq sequencer. Ewes grazing HE had higher serum non-esterified fatty acid (NEFA) (P = 0.024) compared with ewes in ME pasture at d 115. Both the Observed OTUs and Shannon Index tended (P = 0.08, P = 0.06) to be greater for HE than for ME on d 115. At the genus level, Prevotella abundance increased with time in both ME and HE (on d1, d51 and d115: 15.17%, 25.59% and 24.78% in ME; 14.17%, 18.10% and 19.41% in HE). Other genera including unclassified Lachnospiraceae, unclassified Coriobacteriaceae and unclassified Veillonellaceae exhibited higher abundances in HE at d 51 (3.72%, 2.07% and 11.22%) compared with ME (2.06%, 1.28% and 7.42%). The predictor microbiota for HE and ME were identified by a random forest classification model. The HE predictors included bacteria associated with unclassified Coriobacteriaceae and Ruminococcaceae. Other species associated with Prevotella and Clostridiales could be microbial predictors for ME. The OTUs related to Prevotella and Lachnospiraceae were negatively correlated with serum concentrations of prolactin. Negative correlations with NEFA were observed in microbiota such as species affiliated to unclassified Clostridiales and Prevotella. Species associated with Bacteroidetes and Coriobacteriaceae exhibited a positive correlation with NEFA. Our study confirmed that the rumen microbiome populations were affected by high levels of toxins in endophyte-infected tall fescue and were associated with host hormone and energy metabolism.