Effects of high concentrate rations on ruminal fermentation and microbiota of yaks

Abstract

Ruminal microflora is closely correlated with the ruminant’s diet. However, information regarding the effect of high concentrate diets on rumen microflora in yaks is lacking. In the current study, 24 healthy male yaks were randomly assigned to two groups, each fed with different diets: less concentrate (LC; concentrate: coarse = 40: 60) and high concentrate (HC; concentrate: coarse = 80: 20) diets. Subsequently, a 21-day feeding trial was performed with the yaks, and rumen fluid samples were collected and compared using 16 s rRNA sequencing. The results showed that NH3-N, total VFA, acetate, butyrate, isobutyrate, and isovalerate were significantly higher in the HC group than that in the LC group (p < 0.05), while microbial diversity and richness were significantly lower in the HC group (p < 0.05). Principal coordinate analysis indicated that rumen microflora was significantly different in LC and HC groups (p < 0.05). In the rumen, phyla Firmicutes and Bacteroidota were the most abundant bacteria, with Firmicutes being more abundant, and Bacteroidota being less abundant in the HC group than those found in the LC group. Christensenellaceae_R-7_group and Prevotella are the highest abundant ones at the genus level. The relative abundance of Acetitomaculum, Ruminococcus, and Candidatus_Saccharimonas were significantly higher in the HC group than that in the LC group (p < 0.05), while the relative abundance of Olsenella was significantly lower in the HC group than in the LC group (p < 0.05). Compared to the LC group, the relative abundance of Prevotella, Ruminococcus, and Candidatus_Saccharimonas was significantly higher in the HC group. The relative abundances of Prevotella, Prevotellaceae_UCG-003, Olsenella, Ruminococcus, Acetitomaculum, Candidatus_Saccharimonas, and NK4A214_group were correlated with ruminal fermentation parameters (p < 0.05). Furthermore, PICRUSt 2 estimation indicated that microbial genes associated with valine, leucine, and isoleucine biosynthesis were overexpressed in the rumen microflora of yaks in the HC group (p < 0.05). Conclusively, our results suggest that high concentrate diets affect the microflora composition and fermentation function in yak rumen. The present findings would provide new insights into the health of yaks under high concentrate feeding conditions and serve as a potent reference for the short-term fattening processes of yaks.

Effects of replacing hybrid giant napier with sugarcane bagasse and fermented sugarcane bagasse on growth performance, nutrient digestibility, rumen fermentation characteristics, and rumen microorganisms of Simmental crossbred cattle

“…At the phylum level, the highest abundance in the three treatment groups was the Firmicutes , followed by the Bacteroidetes , which is similar to the results of Pang et al (2022) but opposite to those of Mu et al (2019) . Species in the Firmicutes are rich in cellulases and hemicellulases ( Gharechahi and Salekdeh, 2018 ) which play important roles in the degradation of fibrous materials ( Evans et al, 2011 ).…”

“…Christensenellaceae_R-7_group belongs to the Firmicutes (Waters and Ley, 2019) which are mainly involved in the degradation of cellulose and hemicellulose in the rumen (Evans et al, 2011;Ran et al, 2021) and usually have a high abundance in the rumen of ruminants fed diets with a high fiber content (Thoetkiattikul et al, 2013). The higher abundance of Christensenellaceae_R-7_group in the SB group may be related to the presence of 20% bagasse containing less degradable fiber material in this group (Pang et al, 2022). Succiniclasticum is an important member of the core rumen microbiota, is involved in starch degradation, and is a major contributor to the conversion of succinic acid to propionic acid in the rumen (Ran et al, 2021), with a higher abundance in the rumen of ruminants fed highenergy and high-concentrate diets (Bi et al, 2018;Liu et al, 2019).…”

The Impact of Different Dietary Ratios of Soluble Carbohydrate-to-Neutral Detergent Fiber on Rumen Barrier Function and Inflammation in Dumont Lambs

“…When LPS binds to the TLR4 complex, IκB phosphorylation leads to the release of NF-κB and a cascade reaction to activate MAPKs, thus promoting inflammatory cytokine expression [ 13 , 48 , 49 ]. A high SCHO-to-NDF ratio in the diet induces significant changes in the gastrointestinal microbiota of ruminants, resulting in increased numbers of Gram-negative bacteria, increased concentrations of LPS and histamine, and the activation of the NF-κB and MAPK pathway, leading to inflammatory damage in the rumen epithelium [ 45 , 50 , 51 ]. In this study, we found that feeding a high SCHO-to-NDF ratio diet resulted in a lower pH, a higher LPS concentration, and the increased phosphorylation of p65, IκB, and JNK proteins in the rumen epithelium compared to those in the low-SCHO:NDF group.…”

Metabolomics and proteomics insights into subacute ruminal acidosis etiology and inhibition of proliferation of yak rumen epithelial cells in vitro

“…SCFA plays a vital role in shaping the internal rumen environment, maintaining electrolyte balance, and serving as an energy source for host cells [49][50][51]. The concentration of SCFA in the rumen fluid ranges from around 60 mmol/L under normal diets to over 70 mmol/L in high-concentrate diets [22,52]. Moreover, our previous experiment in vitro showed that the concentrations of SCFA above 60 mmol/L gradually and dosage-dependently suppressed the proliferation of YRECs, with an inhibition rate reaching approximately 50% at 120 mmol/L SCFA [30].…”