Title: Ligularia virgaurea improved nutrient digestion, ruminal fermentation, and bacterial composition in Tibetan sheep grazing on the Qinghai–Tibetan plateau in winter
Journal: Animal Feed Science and Technology
Impact factor: 3.313
Abstract: Modulation of rumen microbiota is a prominent function of dietary supplements to improve the performance and health of grazing ruminants. This experiment evaluated the influence of the amount of Ligularia virgaurea (LV) supplementation on nutrient digestibility, ruminal fermentation, and bacterial composition in Tibetan sheep consuming low-quality, cold-season forage. Thirty-two intact male yearling Tibetan rams (30 ± 1.66 kg body weight, mean ± SD) were used in a completely randomized block design, randomly assigned among four experimental groups, and fed for 35 days. Sheep were fed a basal diet (freshly native pasture) with either no LV (control), or with 100, 200, or 300 mg/kg BW of LV per animal/d, with prairie forage available ad libitum. Results showed that the dry matter intake and digestibility of nutrients differed significantly across treatments (P < 0.05). Ruminal fermentation parameters and the bacterial composition were affected by the dietary LV supplementation amount and there was a strong correlation between them. Bacteroidetes and Firmicutes were the dominant phyla in the ruminal bacterial community for all groups. Prevotella and Rikenellaceae_RC9_gut group were the dominant genera, whose relative abundances decreased and increased, respectively, with increasing LV supplementation. Overall, LV ingestion improved the rumen bacterial community abundance associated with cellulose and saccharide degradation, thus contributing to nutrient digestibility and energy supply in Tibetan sheep in the cold season. A comparison of metabolic functional prediction across the four treatment groups revealed an enrichment of metabolic pathways related to lipid metabolism, metabolism of terpenoids and polyketides, folding, sorting and degradation, and membrane transport in the LV supplementation groups. Genomics-based knowledge on the benefits of autochthonous functional plants to Tibetan sheep ruminal microbiota functions and compositions will contribute to their selection as antibiotic alternatives for traditional pastureland.