Effects of winter barn feeding and grazing on growth performance, meat quality and rumen fungal community of Tibetan sheep

Abstract

The grazing grassland ecosystem on the Qinghai-Tibetan Plateau is highly impacted by seasonal temperature variations. During the long cold season, the biomass and nutrient contents of forage grass do not meet the nutritional needs of grazing livestock and seriously affect growth performance and livestock products. This study investigated different feeding strategies on growth performance, meat quality and rumen fungal community of Tibetan sheep in the winter. Twelve one-year-old healthy castrated Tibetan sheep with similar initial body weights were randomly grouped into traditional grazing (TG) and barn feeding (BF) groups. The TG sheep were labelled and grazed on the local cool-season pasture without feed supplementing, while BF sheep were fed a mixed diet in feeding shed. Compared with the TG group, significantly increased body weight and average daily weight gain (ADG) were observed in the BF group (p < 0.001), which resulted in a significant increase in the hot carcase weight, net meat weight, carcase rate and net meat rate (p < 0.01). Moreover, the longissimus dorsi muscle of the BF group showed significantly increased muscle fibre diameter, perimeter, and area and increased crude protein and ether extract contents (p < 0.01), while the meat tenderness and amino acid content were reduced. ITS high-throughput sequencing showed that Ascomycota was the predominant fungal phylum in the rumen of Tibetan sheep. At the genus level, the rumen of TG sheep presented higher proportions of Preussia, Anaeromyces and Pilidium, while the most abundant genera in the BF sheep were Penicillium, Acaulium and Vishniacozyma. In summary, BF strategy enhanced the relative abundance of several dominant fungal genera related to the nutrient absorption and metabolism capacity, and effectively improves the growth and slaughter performance and affects meat quality of Tibetan sheep in the winter.