Nutritional Models of Experimentally-Induced Subacute Ruminal Acidosis (SARA) Differ in Their Impact on Rumen and Hindgut Bacterial Communities in Dairy Cows

Abstract

Effects of subacute ruminal acidosis (SARA) challenges on the bacteria in rumen fluid, cecal digesta, and feces of dairy cows were determined using 16S rRNA gene pyrosequencing and real-time quantitative PCR. Six non-lactating Holstein cows with cannulas in the rumen and cecum were used in a 3 × 3 Latin square arrangement of treatments. During the first 3 wk of each experimental period, cows received a control diet containing 70% forages on a dry matter (DM) basis. In wk 4 of each period, cows received one of three diets: (1) the control diet; (2) a diet in which 34% of the dietary DM was replaced with pellets of ground wheat and barley (GBSC); or (3) a diet in which 37% of dietary DM was replaced with pellets of ground alfalfa (APSC). Rumen fluid, cecal digesta and feces were collected on d 5 of wk 4 of each period and the composition of the bacterial community was studied. Rumen fermentation responses were reported in a companion study. Both SARA-inducing challenges resulted in similar digesta pH depressions (as shown by the companion study), and reduced bacterial richness and diversity in rumen fluid, but GBSC had the larger effect. None of the challenges affected these measures in cecal digesta, and only GBSC reduced bacterial richness and diversity in feces. Only GBSC reduced the abundance of Bacteroidetes in rumen fluid. Abundances of limited number of bacterial genera identified by 16S rRNA gene sequencing in the rumen, cecum and feces were affected by the GBSC. The APSC did not affect any of these abundances. Both challenges increased the abundances of several starch, pectin, xylan, dextrin, lactate, succinate, and sugar fermenting bacterial species in the rumen, cecum, and feces as determined by qPCR. Only GBSC increased that of Megasphaera elsdenii in the rumen. Both challenges decreased the abundance of Streptococcus bovis, and increased that of Escherichia coli, in cecal digesta and feces, with GBSC having the larger effect. These results showed that the SARA challenges caused moderate and reversible changes of the composition of the bacteria in the foregut and hindgut, with the greater changes observed during GBSC.

Effects of lipopolysaccharide dosing on bacterial community composition and fermentation in a dual-flow continuous culture system

“…Also, a decrease of acetate: propionate ratio was also observed in WBD. This is generally observed when animals are switched from a high-forage to a high-grain diet or in a grain-induced SARA (Plaizier et al, 2012(Plaizier et al, , 2017. Molar proportion of acetate and propionate in LPSD was not different from CON, and thus no difference was present in acetate to propionate ratio between LPSD and CON as well.…”

“…The goal of the control diet was to keep the pH above 6 during the experiment. The SARA was induced following the modified model of Keunen et al (2002) and Gozho et al (2007): 40% of the DM of CON was replaced with 50% ground wheat and 50% ground barley, which was the same inclusion level of wheat and barley used in Plaizier et al (2017). The forage: concentrate ratio was 39:61 in WBD, which was the same forage: concentrate ratio that caused SARA in the study of Gozho et al (2006).…”

Phylogenetic and functional adaption of the gastrointestinal microbiome of goats kept at high altitude (4800 m) under intensive or extensive rearing conditions

“…Our results indicate occurrence of rumen acidosis in the drylot goats. The classic view of rumen acidosis is that the rapid fermentation of feed produces more lactic acid, propionate, and butyrate [56] and the rumen pH drops to a certain level. This results in an inhibition of the cellulose bacteria and an increase in acid-tolerant bacteria [57].…”

Male castration alters the gut microbiota, leading to increased serum levels of branched-chain amino acids and adiposity

“…In the current study, the postpubescent cattle were fed a high-concentrate diet containing 72% of solid feed ingredients with low roughage (Additional file 2: Supplementary Table S1). The effects of feeding high-concentrate diet on ruminal acidosis are described elsewhere [32]. Since feeding animals suffering from ruminal acidosis high-concentrate diet elevates the risk of hindgut acidosis [33,34], the enrichment of starch-degrading amylolytic microbes (e.g., the phylum Bacteroidetes) [35] in the rectum and the high level of lactic acid in the serum of postpubescent male cattle might suggest the onset and/or progression of hindgut acidosis ( Fig.…”