# Effect of Roughage Source on the Composition and Colonization of Rumen Bacteria and Methanogens in Dumont and Mongolian Sheep

## TL;DR

This study shows how the type of roughage and sheep breed affect rumen microbes, influencing feed efficiency and growth.

## Contribution

The study identifies breed-specific microbial responses to roughage sources, revealing interactions between diet and genetics in ruminants.

## Key findings

- Alfalfa hay increased feed intake and weight gain in sheep compared to corn straw.
- Dumont sheep showed higher feed intake than Mongolian sheep.
- Rumen microbial diversity and composition varied with roughage type and breed.

## Abstract

The rumen microbial community plays a critical role in the production efficiency of ruminants and may be influenced by factors such as the animal breed and diet. We investigated the effects of breed (Dumont and Mongolian sheep) and roughage source (alfalfa hay and corn straw) on the rumen microbial community. We found that the roughage type strongly affects both the feed efficiency and rumen microbial community composition, and this effect was influenced by the interaction between the breed and roughage source. The two sheep breeds fed different roughages exhibited distinct rumen microbial communities, indicating that ruminal microbiota are simultaneously affected by diet and genetic differences, thereby altering the feed efficiency.

Understanding the influence of the sheep breed and roughage source on the composition of rumen bacteria and methanogens is essential for optimizing roughage efficiency. The experiment employed a 2 × 2 factorial design. Twenty-four Dumont and Mongolian sheep (initial body weight of 18.94 ± 1.01 kg) were randomly assigned by breed to two dietary treatment groups (AH: alfalfa hay; CS: corn straw); the experiment lasted 90 days. The results showed that sheep fed alfalfa hay diets had a higher feed intake and weight gain, and Dumont sheep had a higher feed intake than Mongolian sheep (p < 0.05). The diversity and composition of ruminal bacteria and methanogens differed between Dumont and Mongolian sheep fed either AH or CS diets. The taxonomic analysis revealed a distinct clustering pattern based on the roughage source, but not on the breed. When fed a corn straw diet, the bacterial Chao1 index of Dumont sheep increased (p < 0.05), while the diversity and richness of methanogens in Mongolian sheep increased (p < 0.05). Additionally, we have identified unique biomarkers for the rumen bacteria and methanogens of Dumont and Mongolian sheep in response to different roughage sources. The results suggest that the differences in the microbiota of the sheep were associated with the roughage source and breed. The higher growth performance of Dumont sheep might be attributed to the increase in bacterial diversity and the decrease in methanogenic bacteria diversity.