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Selected Publication:

Publication type: Journal Article
Document type: Full Paper

Year: 2017

Author(s): Wetzels, SU; Mann, E; Pourazad, P; Qumar, M; Pinior, B; Metzler-Zebeli, BU; Wagner, M; Schmitz-Esser, S; Zebeli, Q

Title: Epimural bacterial community structure in the rumen of Holstein cows with different responses to a long-term subacute ruminal acidosis diet challenge.

Source: J Dairy Sci. 2017; 100(3):1829-1844



Authors Vetmeduni Vienna:

Mann-Selberherr Evelyne
Metzler-Zebeli Barbara
Pinior Beate
Pourazad Poulad
Qumar Muhammad
Schmitz-Esser Stephan
Wagner Martin
Wetzels Stefanie
Zebeli Qendrim

Vetmed Research Units
Institute of Animal Nutrition and Functional Plant Compounds
Unit of Food Microbiology
Unit of Veterinary Public Health and Epidemiology
University Clinic for Swine


Project(s): d-i.INFLACOW: Characterization and prevention of diet-induced inflammation and related immune and metabolic disorders in dairy cows


Abstract:
Subacute ruminal acidosis (SARA) is a prevalent metabolic disorder in cattle, characterized by intermittent drops in ruminal pH. This study investigated the effect of a gradual adaptation and continuously induced long-term SARA challenge diet on the epimural bacterial community structure in the rumen of cows. Eight rumen-cannulated nonlactating Holstein cows were transitioned over 1 wk from a forage-based baseline feeding diet (grass silage-hay mix) to a SARA challenge diet, which they were fed for 4 wk. The SARA challenge diet consisted of 60% concentrates (dry matter basis) and 40% grass silage-hay mix. Rumen papillae biopsies were taken at the baseline, on the last day of the 1-wk adaptation, and on the last day of the 4-wk SARA challenge period; ruminal pH was measured using wireless sensors. We isolated DNA from papillae samples for 16S rRNA gene amplicon sequencing using Illumina MiSeq. Sequencing results of most abundant key phylotypes were confirmed by quantitative PCR. Although they were fed similar amounts of concentrate, cows responded differently in terms of ruminal pH during the SARA feeding challenge. Cows were therefore classified as responders (n = 4) and nonresponders (n = 4): only responders met the SARA criterion of a ruminal pH drop below 5.8 for longer than 330 min/d. Data showed that Proteobacteria, Firmicutes, and Bacteroidetes were the most abundant phyla, and at genus level, Campylobacter and Kingella showed highest relative abundance, at 15.5 and 7.8%, respectively. Diversity analyses revealed a significant increase of diversity after the 1-wk adaptation but a decrease of diversity and species richness after the 4-wk SARA feeding challenge, although without distinction between responders and nonresponders. At the level of the operational taxonomic unit, we detected diet-specific shifts in epimural community structure, but in the overall epimural bacterial community structure, we found no differences between responders and nonresponders. Correlation analysis revealed significant associations between grain intake and operational taxonomic unit abundance. The study revealed major shifts in the 3 dominating phyla and, most importantly, a loss of diversity in the epimural bacterial communities during a long-term SARA diet challenge, in which 60% concentrate supply for 4 wk was instrumental rather than the magnitude of the drop of ruminal pH below 5.8.


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