Induction of Subacute Ruminal Acidosis Affects the Ruminal Microbiome and Epithelium

Abstract

Subacute ruminal acidosis (SARA) negatively impacts the dairy industry by decreasing dry matter intake, milk production, profitability, and increasing culling rate and death loss. Six ruminally cannulated, lactating Holstein cows were used in a replicated incomplete Latin square design to determine the effects of SARA induction on the ruminal microbiome and epithelium. Experimental periods were 10 days with days 1–3 for ad libitum intake of control diet, followed by 50% feed restriction on day 4, and ad libitum access on day 5 to the basal diet or the basal diet with an additional 10% of a 50:50 wheat/barley pellet. Based on subsequent ruminal pH, cows were grouped (SARA grouping; SG) as Non-SARA or SARA based on time <5.6 pH (0 and 3.4 h, respectively). Ruminal samples were collected on days 1 and 6 of each period prior to feeding and separated into liquid and solid fractions. Microbial DNA was extracted for bacterial analysis using 16S rRNA gene paired-end sequencing on the MiSeq Illumina platform and quantitative PCR (qPCR). Ruminal epithelium biopsies were taken on days 1 and 6 before feeding. Quantitative RT-PCR was used to determine gene expression in rumen epithelium. Bray–Curtis similarity indicated samples within the liquid fraction separated by day and coincided with an increased relative abundance of genera Prevotella, Ruminococcus, Streptococcus, and Lactobacillus on day 6 (P < 0.06). Although Firmicutes was the predominant phyla in the solid fraction, a SG × day interaction (P < 0.01) indicated a decrease on day 6 for SARA cows. In contrast, phylum Bacteroidetes increased on day 6 (P < 0.01) for SARA cows driven by greater genera Prevotella and YRC22 (P < 0.01). Streptococcus bovis and Succinivibrio dextrinosolvens populations tended to increase on day 6 but were not affected by SG. In ruminal epithelium, CLDN1 and CLDN4 expression increased on day 6 (P < 0.03) 24 h after SARA induction and a tendency for a SG × day interaction (P < 0.10) was observed for CLDN4. Overall, results indicate more rapid adaptation to an induced bout of SARA in the solid fraction ruminal microbiome compared with ruminal epithelium.

Metagenomic profiles of the rumen microbiota during the transition period in low‐yield and high‐yield dairy cows

“…On the other hand, a high abundance of Selenomonas could reduce lactate accumulation, because these bacteria can utilize lactate to generate propionate (Wang et al, ). In addition, Succinivibrio converts soluble carbohydrates to succinate in the rumen (McCann et al, ). The low abundance of Bifidobacterium and high abundance of Succinivibrio in the HY group might indicate that lactate was smoothly converted to succinate in this group.…”

“…Analysis of the rumen microbiota could provide detailed information about the community structure and metabolic properties of the microbiota, which in turn could be used to improve feeding strategies for optimal milk production in ruminants (McCann et al, ). Feeding strategies to regulate the rumen microbiota structure are therefore expected to improve feed digestion to enhance microbial protein synthesis and to minimize nutrient loses (Kim, Morrison, & Yu, ).…”

Understanding host-microbial interactions in rumen: searching the best opportunity for microbiota manipulation

“…Although metabolic dysfunction and health of the rumen (acidosis and subacute acidosis) are also linked to the composition and functions of the rumen microbiota [12–14], host-microbial interactions in the rumen have mainly been studied to maximize the production performance of ruminant livestock species. Moreover, the majority of studies on host-microbial interactions in the rumen are based on adult animals, reporting associations between the rumen microbiota and feed efficiency in beef [15–17] and dairy [18, 19] cattle, methane emission in cattle and sheep [20–22], milk production in dairy cows [18, 19] as well as the susceptibility to subacute acidosis in beef [23] and dairy [24].…”

Jersey steer ruminal papillae histology and nutrigenomics with diet changes

“…In lactating Holstein cows, both CLDN1 and CLDN4 expression were upregulated in rumen epithelium with the lower pH of induced subacute ruminal acidosis (SARA). However, no mechanism for this upregulation has been found (McCann et al, ). Furthermore, CLDN4 expression was significantly increased in the intestinal mucosa lesion of mice (Tamura et al, ).…”

“…Furthermore, DSG1 was downregulated with high amounts of grain (Steele, Croom, et al, ). Further, the expression of DSG1 was found to be upregulated in the rumen epithelium of cattle recovering from an acidotic bout (McCann et al, ). In the rumen epithelium of cattle fed different proportions of grain in the diet, DSG1 expression was not affected significantly (Figure ).…”