Microbiome

Effects of stress tolerance and feeding strategy on the rumen microbial communities of Rasa Aragonesa ewes

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Abstract

The rumen microbiota plays a key role in nutrient digestion, feed efficiency and overall health in ruminants, and is influenced by both diet and stressors such as water deprivation or parasite infection. This study aimed to investigate the influence of phenotypic ewes' stress tolerance and sainfoin supplementation on rumen microbiome composition of ewes subjected to 40% water restriction for 4 weeks and to Haemonchus contortus L3 infection (10,000/ewe), to improve our understanding of the relationship between host stress-response phenotype, diet and rumen microbiota. Forty Rasa Aragonesa ewes raised under semi-extensive conditions were selected from a previous experiment in which animals were exposed to combined heat stress and total water restriction for 5 days. Stress tolerance was assessed using the neutrophil-to-lymphocyte (N:L) ratio as an indicator of physiological stress response, and ewes were classified as having high tolerance (HT) or low tolerance (LT) to abiotic stress. Within each group, half of the ewes were fed 400 g/d a total mixed ration (10 HT-CONTROL and 10 LT-CONTROL), while the other half received 400 g/d of sainfoin pellets (10 HT-SAIN and 10 LT-SAIN). Both groups were also provided with 1 kg/d of straw. After 9 weeks, samples of ruminal content were collected and DNA was extracted with the Dneasy PowerSoil Pro Kit. Microbial DNA sequencing was performed using an advanced nanopore long-reading metagenomic sequencer (GridION). For the bioinformatics analysis, quality control was performed with the NanoPlot software. Reads were analysed with the SqueezeMeta pipeline for long reads (sqm_longreads.pl). Alpha diversity was analysed by calculating Observed and Shannon indices, while beta diversity was evaluated through principal component analysis (PCA) and PERMANOVA. Differential abundance analysis was performed using a bias-corrected log-linear model implemented in the ANCOM-BC2 (Analysis of Composition of Microbiomes with Bias Correction 2) R package. Different microbial diversity was observed between the 4 groups, and between feed (SAIN vs CONTROL) and abiotic stress tolerance (HT vs LT) groups. Within the feed contrast, Olsenella, Faecalibacterium, and Treponema were more abundant in the sainfoin group, potentially enhancing lactate-related fermentation and fibre digestion. In contrast, Ruminobacter, Succinimonas, and Succinivibrio were enriched in the control group, suggesting a greater potential for propionate and succinate production, key pathways in rumen fermentation and energy metabolism. Differences in relative abundance were also observed between abiotic stress tolerance groups. Ewes of HT group exhibited higher abundances of Methanobrevibacter, Methanosphaera, Eubacterium, Blautia, and Coprococcus. Methanobrevibacter and Methanosphaera are the main methanogenic archaea in the rumen. Eubacterium, Blautia, and Coprococcus are key butyrate producers that help maintain redox balance and epithelial health, indicating fermentative efficiency. These findings highlight the influence of phenotypic host stress tolerance and diet on rumen microbial communities, improving our understanding of host-microbiome interactions under environmental stress.

Keywords: 2026

How to Cite:

Pérez-Redondo, S., Reinoso‑Peláez, E., Lobón, S., Joy, M., Calvete, C., Baila, C., Serrano, M. & Calvo, J., (2026) “Effects of stress tolerance and feeding strategy on the rumen microbial communities of Rasa Aragonesa ewes”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2284563. doi: https://doi.org/10.31274/wcgalp.23593

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