Effects of Dietary Energy Levels on Rumen Fermentation, Microbial Diversity, and Feed Efficiency of Yaks (Bos grunniens)

Abstract

The microbial community of the yak ( Bos grunniens ) rumen plays an important role in surviving the harsh Tibetan environment where seasonal dynamic changes in pasture cause nutrient supply imbalances, resulting in weight loss in yaks during the cold season. A better understanding of rumen microbiota under different feeding regimes is critical for exploiting the microbiota to enhance feed efficiency and growth performance. This study explored the impact of different dietary energy levels on feed efficiency, rumen fermentation, bacterial community, and abundance of volatile fatty acid (VFA) transporter transcripts in the rumen epithelium of yaks. Fifteen healthy castrated male yaks were divided into three groups and fed with low (YL), medium (YM), and high energy (YH) levels diet having different NEg of 5.5, 6.2, and 6.9 MJ/kg, respectively. The increase in feed efficiency was recorded with an increase in dietary energy levels. The increase in dietary energy levels decreased the pH and increased the concentrations of acetate, propionate, butyrate, and valerate in yak rumens. The increase in the mRNA abundance of VFA transporter genes ( MCT1 , DRA , PAT1 , and AE2 ) in the rumen epithelium of yaks was recorded as dietary energy level increased. High relative abundances of Firmicutes and Bacteroidetes were recorded with the increase in dietary energy levels. Significant population shifts at the genus level were recorded among the three treatments. This study provides new insights into the dietary energy-derived variations in rumen microbial community.

Comparing the Bacterial Community in the Gastrointestinal Tracts Between Growth-Retarded and Normal Yaks on the Qinghai–Tibetan Plateau

“…A previous study reported that Firmicutes had an important role in the process of energy absorption (Ley et al, 2006). Additionally, Firmicutes are known to be involved in the degradation of oligosaccharides, starch, and cellulose (Ahmad et al, 2020). In the rumen of yaks, the research found that the relative abundance of Firmicutes in the feeding group was significantly increased as compared with the grazing group (Zhou et al, 2017).…”

Dandelion (Taraxacum mongolicum Hand.-Mazz.) Supplementation-Enhanced Rumen Fermentation through the Interaction between Ruminal Microbiome and Metabolome

“…Notably, Hayashi et al [ 25 ] demonstrated that Dialister populations were positively correlated with hyposalivation, which could play an important function in changing the rumen buffering ability and fluid turnover. Erysipelotrichaceae_UCG_002 belongs to the family of Erysipelotrichaceae and was previously reported to be associated with VFA synthesis and energy generation [ 26 ]. The specific association of Erysipelotrichaceae_UCG_002 with VFA is still elusive, and thus requires an in-depth exploration in the future.…”

Effects of a Grain Source (Corn Versus Barley) and Starter Protein Content on Performance, Ruminal Fermentation, and Blood Metabolites in Holstein Dairy Calves

“…Corn starch is less available for ruminal fermentation than barley grain and, hence, there is a need to conduct more extensive processing, such as steam-flaking instead of a simple grinding, to achieve higher availability of starch [ 1 , 12 ]. The main energy source for ruminants is SCFA that could be an indicator of the ruminal fermentation [ 32 ]. Therefore, the greater SCFA observed in BG diets, the higher the “whole body” efficiency towards greater gain and productivity.…”

“…Among individual SCFA the molar proportions of propionate and butyrate were increased in calves fed BG, and in contrast, acetate was in a lower range in this diet. Propionate and butyrate are two main ruminal volatile fatty acids that function as chemical stimuli for rumen development and they could potentially supply greater energy than acetate [ 32 ].…”