Glucogenic and lipogenic diets affect in vitro ruminal microbiota and metabolites differently

Abstract

This study was conducted to evaluate the effects of two glucogenic diets (C: ground corn and corn silage; S: steam-flaked corn and corn silage) and a lipogenic diet (L: sugar beet pulp and alfalfa silage) on the ruminal bacterial and archaeal structures, the metabolomic products, and gas production after 48 h in vitro fermentation with rumen fluid of dairy cows. Compared to the C and S diets, the L dietary treatment leaded to a lower dry matter digestibility (DMD), lower propionate production and ammonia-nitrogen concentration. The two glucogenic diets performed worse in controlling methane and lactic acid production compared to the L diet. The S diet produced the greatest cumulative gas volume at any time points during incubation compared to the C and L diet. The metabolomics analysis revealed that the lipid digestion especially the fatty acid metabolism was improved, but the amino acid digestion was weakened in the L treatment than in other treatments. Differences in rumen fermentation characteristics were associated with (or resulting from) changes in the relative abundance of bacterial and archaeal genera. The rumen fluid fermented with L diet had a significantly higher number of cellulolytic bacteria, including the genera of Ruminococcus, Butyrivibrio, Eubacterium, Lachnospira, unclassified Lachnospiraceae, and unclassified Ruminococcaceae. The relative abundances of amylolytic bacteria genera including Selenomonas_1, Ruminobacter, and Succinivibrionaceae_UCG-002 were higher in samples for diets C and S. The results indicated that the two glucogenic diets leaded to a higher relative abundance of bacteria which functions in succinate pathway resulting in a higher propionate production. The steam-flaked corn diet had a higher gas production and lower level of metabolites in fatty acids and amino acids. Most highly abundant bacteria were observed to be not sensitive to dietary alterations of starch and fiber, except for several amylolytic bacteria and cellulolytic bacteria. These finding offered new insights on the digesting preference of ruminal bacteria, which can assist to improve the rumen functioning.

Ruminal inocula with distinct fermentation profiles differentially affect the in vitro fermentation pattern of a commercial algal blend

“…As previously mentioned, diet is known to greatly affect the composition and activity of the ruminal microbiota. Although changes in the ruminal microbiota can partly explain the results obtained in our study, Jami and Mizrahi (57) reported that differences in ruminal bacterial populations among animals fed the same diet were substantially higher than those promoted by different diets. Moreover, the authors concluded that despite the variation in bacterial taxa among animals, the microbiota was phylogenetically highly similar (82%) and thus did not affect fermentation ability.…”

“…Moreover, the authors concluded that despite the variation in bacterial taxa among animals, the microbiota was phylogenetically highly similar (82%) and thus did not affect fermentation ability. Hua et al ( 58 ) compared the effects of glucogenic and lipogenic diets on ruminal bacterial community structure, fermentation intermediary metabolites, and methane production following 48 h of incubation with a ruminal inoculum. Although several amylolytic and cellulolytic bacteria were found to be sensitive to dietary differences, most highly abundant bacteria were stable or were only marginally affected, thus highlighting the relevance of the microbiota profile of ruminal inocula in short-term in vitro fermentation studies.…”