Abstract
Subacute rumen acidotic (SARA) conditions are a consequence of high grain feeding. Recent work has shown that the pattern of grain feeding can significantly impact the rumen epimural microbiota. In a continuation of these works, the objective of this study was to determine the role of grain feeding patterns on the colonization and associated changes in predicted functional properties of the fiber-adherent microbial community over a 48 h period. Eight rumen-cannulated Holstein cows were randomly assigned to interrupted or continuous 60%-grain challenge model (n = 4 per model) to induce SARA conditions. Cows in the continuous model were challenged for 4 weeks, whereas cows of interrupted model had a 1-wk break in between challenges. To determine dynamics of rumen fiber-adherent microbial community we incubated the same hay from the diet samples for 24 and 48 h in situ during the baseline (no grain fed), week 1 and 4 of the continuous grain feeding model as well as during the week 1 following the break in the interrupted model. Microbial DNA was extracted and 16SrRNA amplicon (V3-V5 region) sequencing was done with the Illumina MiSeq platform. A significant decrease (P < 0.001) in fiber-adherent rumen bacterial species richness and diversity was observed at the end of a 4 week continuous SARA challenge in comparison to the baseline. A total of 159 operational taxonominc units (OTUs) were identified from the microbial population representing > 0.1% relative abundance in the rumen, 18 of which were significantly impacted by the feeding challenge model. Correlation analysis of the significant OTUs to rumen pH as an indicator of SARA showed genus Succiniclasticum had a positive correlation to SARA conditions regardless of treatment. Predictive analysis of functional microbial properties suggested that the glyoxylate/dicarboxylate pathway was increased in response to SARA conditions, decreased between 24h to 48h of incubation, negatively correlated with propanoate metabolism and positively correlated to members of the Veillonellaceae family including Succiniclasticum spp. This may indicate an adaptive response in bacterial metabolism under SARA conditions. This research clearly indicates that changes to the colonizing fiber-adherent rumen microbial population and their predicted functional genes occur in both the short (48 h) and long term (4 wk) under both continuous and interrupted SARA challenge models.
Highlights
The rumen microbial community is highly impacted by diet and host factors such as age and health status [1]
It is well understood that the replacement of fiber with more readily fermentable carbohydrates impacts these microorganisms and alters the dynamics of the rumen ecosystem [1, 2] leading to metabolic diseases such as subacute ruminal acidosis (SARA) [3, 4]
Based on this we hypothesized that fiber-adherent microbial population would have less cellulolytic bacteria, decreased diversity and down-regulated carbohydrate metabolism within a 48 h period on a intermittent SARA model compared to a long term model which would allow for host and microbe adaptation
Summary
The rumen microbial community is highly impacted by diet and host factors such as age and health status [1]. Since fiber-adherent ruminal microorganisms require longer time for colonization and fermentation in the rumen [3], intermittent SARA conditions may be a greater challenge for the establishment of particle associated bacterial populations. Based on this we hypothesized that fiber-adherent microbial population would have less cellulolytic bacteria, decreased diversity and down-regulated carbohydrate metabolism within a 48 h period on a intermittent SARA model compared to a long term model which would allow for host and microbe adaptation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
