Article

Reducing methane emissions in Tibetan sheep at high altitudes through indoor feeding of a low-fibre total mixed pellet diet

Mengjiao Sun1,2, Hangqi Han1, Xiaoxue Zhang1, Huiyun Liu1, He Ding1, na Ta1, Xiaozhen Liu1, Xiaoqing Zhang1,3,*
Author Information & Copyright
1Grassland Research of Chinese Academy of Agricultural Sciences, Hohhot 010010, China.
2College of Prataculture, Qingdao Agricultural University, Qingdao 266109, China.
3Northern Agriculture and Livestock Husbandry Technology Innovation Center, Hohhot 010010, China.
*Corresponding Author: Xiaoqing Zhang, Grassland Research of Chinese Academy of Agricultural Sciences, Hohhot 010010, China. Northern Agriculture and Livestock Husbandry Technology Innovation Center, Hohhot 010010, China. E-mail: zhangxiaoqing@caas.cn.

© Copyright 2025 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study aimed to the effects of low-fibre total mixed diets on ruminal microorganisms and the potential mechanisms of methane (CH<sub>4</sub>) reduction in high-altitude regions remain understudied. In this study, 18 Tibetan sheep of the same age and weight were divided into two groups at random: the grazing group (GF, control) and the house-feeding group (HF). The GF group grazed on natural pasture, while the HF group was fed a low-fibre total mixed pellet diet indoors. The experiment lasted 78 days, and CH<sub>4</sub> emissions were measured via gas exchange in CH<sub>4</sub> emissions monitoring cage during the final three days. The results showed that compared to the GF group, the HF group had significantly higher dry matter intake and average daily gain (<italic>p</italic> &lt; 0.01), and the animals in the HF group experienced an hour delay in the onset of peak CH<sub>4</sub> emissions and had significantly lower (<italic>p</italic> &lt; 0.05) CH<sub>4</sub> emissions per unit of intake and per unit of weight gain. Additionally, the total volatile fatty acid concentration and molar proportion of propionic acid were significantly higher (<italic>p</italic> &lt; 0.01) in the HF group than in the GF group. Rumen metagenome analysis revealed a significant reduction (<italic>p</italic> &lt; 0.05) in rumen microbial diversity in the HF group. Regarding the bacterial composition, the relative abundances of <italic>Prevotella</italic> and <italic>Ruminococcus</italic> were significantly higher (<italic>p</italic> &lt; 0.05), while the abundance of <italic>Butyrivibrio</italic> was significantly lower (<italic>p</italic> &lt; 0.05) in the HF group. Regarding archaeal composition, the relative abundances of the <italic>Methanobrevibacter</italic> genus and <italic>Methanobrevibacter millerae</italic> were significantly higher (<italic>p</italic> &lt; 0.05) in the HF group, whereas the relative abundance of unclassified<italic>_f_Candidatus Methanomethylophilaceae</italic> was significantly lower (<italic>p</italic> &lt; 0.05). Furthermore, the relative abundances of several enzymes involved in methanogenesis (EC: 2.1.1.90, EC: 2.1.1.246, EC: 2.1.1.247, EC: 2.1.1.248, EC: 1.8.7.3, EC: 1.8.98.1, EC: 1.8.98.4, EC: 1.8.98.5 and EC: 1.8.98.6) were significantly reduced (<italic>p</italic> &lt; 0.05) in the HF group. Overall, feeding low-fibre total mixed pellets indoors could reduce CH<sub>4</sub> emissions by modulating the rumen microbiota. This study’s findings provided a valuable reference for optimising feeding management in high-altitude regions to mitigate CH<sub>4</sub> emissions from ruminants.

Keywords: High-altitude region; Tibetan sheep; Grazing; Low-fibre total mixed pellet diet; Rumen metagenome; Methane emissions