Nutrient availability of roughages in isocaloric and isonitrogenous diets alters the bacterial networks in the whole gastrointestinal tract of Hu sheep

Abstract

Background The nutrient availability of roughages could affect the dietary utilization efficiency of ruminants even in isocaloric and isonitrogenous diets. Here, we analyzed the bacterial composition and their metabolic pathways in the gastrointestinal tracts (GITs) of Hu sheep fed with wheat straw (WS) instead of alfalfa (AL) in isocaloric and isonitrogenous diets, trying to explore the reasons from the perspective of GITs bacterial network structure changes. Results We employed 16S rRNA gene sequencing in combination with the Kruskal–Wallis test, Spearman correlation analysis, and other statistical methods to describe the microbiota composition in the GITs of Hu sheep. The results showed after the roughage was replaced from AL to WS, the most positive response occurred in the rumen microbiota, resulting in a more obvious microbiological and functional redundancy phenomenon. Whereas extended biogeographic studies of the GITs bacterial community found opposite results for the hindgut microbiota and metabolism networks compared to the forestomach. The abundance of fiber-degrading bacteria such as Prevotella, Oscillospiraceae NK4A214 group, and Treponema was significantly increased in GITs, but low-efficiency crude fiber degradation inhibited energy use efficiency, the pentose phosphate pathway, gluconeogenesis, and volatile acid synthesis. In addition, dietary shifting from AL to WS decreased the abundance of beneficial bacteria such as the Lachnospiraceae NK3A20 group and Alistipes, thereby enhancing the underlying inflammatory response. Conclusions These findings suggest that feeding untreated WS affected the structure and function of the bacterial network in the GITs due to limited total digestible nutrients, and in particular increases the complexity of the rumen bacterial network, and limit the abundance of bacteria involved in the crude fiber degradation in the hindgut.

Impact of Nutrient Composition on Rumen Microbiome Dynamics and Roughage Degradation

“…In our study, pathways related to amino acid, lipid, nucleotide, carbohydrate, inorganic ion, and coenzyme transport and metabolism, as well as translation and ribosomal structure biogenesis, exhibited an initial decline followed by an increase between 4 and 72 h. This trend suggests microbial competition for nutrients during the early fermentation stage [42], followed by enhanced growth due to nutrient release from cellulose degradation in later fermentation phases [43]. KEGG pathways analysis revealed that carbohydrate metabolism [44], amino acid metabolism [45], and energy metabolism pathways [45] had elevated relative abundances, underscoring their signi cance in the degradation of various roughage types [46]. Notably, ABC transporters were the most abundant functional pathway at level-3, indicating the diverse substrate-binding capabilities of the rumen microbiota [47,48].…”

Deciphering the Impact of Nutrient Composition and Tissue Structure on Rumen Microbiome Dynamics in Roughage Degradation

“…This trend suggests microbial competition for nutrients during the early fermentation stage [68], succeeded by enhanced growth due to nutrient release from cellulose degradation in later fermentation phases [69]. The KEGG pathways analysis revealed that carbohydrate metabolism [70], amino acid metabolism [71], and energy metabolism pathways [71] had elevated relative abundances, underscoring their significance in the degradation of various roughage types [72]. Notably, ABC transporters were the most abundant functional pathway at level-3, indicating the diverse substrate-binding capabilities of the rumen microbiota [73,74].…”

Dietary phytosterols improves the metabolic status of perinatal cows as evidenced by plasma metabolomics and faecal microbial metabolism

“…Not surprisingly, the results of our study found that dietary phytosterols did not affect the fermentation characteristics and alpha diversity of faecal bacteria in perinatal cows. Interestingly, we found that the phytosterols altered the relative abundances of faecal bacteria and their metabolites, partly because the alteration of forestomach digestion would change the digesta composition flowed to the hindgut and subsequently the bacterial network in ruminant faeces [41]. Firmicutes and Bacteroidota were the major bacterial phylum in the faeces of cows.…”