Integrating 16S rRNA Sequencing and LC-MS-Based Metabolomics to Evaluate the Effects of Dietary Crude Protein on Ruminal Morphology, Fermentation Parameter and Digestive Enzyme Activity in Tibetan Sheep

Abstract

The dietary crude protein level could affect ruminal fermentation parameters and the microflora of ruminants. The present study’s aim was to investigate the effects of different protein level diets on ruminal morphology, fermentation parameters, digestive enzyme activity, microflora and metabolites of Tibetan sheep. Ninety weaned lambs (initial weight of 15.40 ± 0.81 kg, 2 months old) were selected and randomly divided into three groups (six pens/treatment, five rams/pen). Dietary treatments were formulated with 13.03% (high protein, HP), 11.58% (moderate protein, MP) and 10.20% (low protein, LP), respectively. Compared with LP, both papillae length and papillae width were significantly promoted in HP and MP (p p p Prevotella 1 and Succiniclasticum and genus Rikenellaceae RC9 gut group and Ruminococcus 1 were observed in HP (p p Prevotella 1 was negatively associated with stearic acid and palmitic acid but positively associated with the taurine. The abundance of genus Ruminococcus 1 was negatively associated with stearic acid, oleic acid, erucic acid, Indole-3-acetamide and palmitic acid but positively associated with 6-hydroxymelatonin. In conclusion, a 13.03% CP level improved ruminal morphology, fermentation parameters and digestive enzyme activities through modulating the microbial community and regulating metabolism in Tibetan sheep.

Keywords

• protein level
• Tibetan sheep
• rumen development
• microbiota
• metabolites