|MCART, JESSICA - Cornell University|
|LIMA, SVETLANA - Weill Medical College - Cornell|
|NEVES, RAFAEL - Purdue University|
|GANDA, ERIKA - Pennsylvania State University|
Submitted to: BMC Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2022
Publication Date: 11/21/2022
Citation: Miles, A.M., McArt, J.A., Lima, S.F., Neves, R.C., Ganda, E. 2022. The association of hyperketonemia with fecal and rumen microbiota at time of diagnosis in a case-control cohort of early lactation cows. BMC Veterinary Research. 18:411. https://doi.org/10.1186/s12917-022-03500-4.
Interpretive Summary: Many dairy cows experience a state of energy deficit as they transition from late gestation to early lactation, and this energy imbalance is indicated by excess ketone bodies in the blood. We hypothesized that this hyperketonemia may be influenced by gut microbiota due to their role in energy metabolism. We performed a case-control cohort study comparing the rumen and fecal microbiomes of healthy and hyperketonemic cows. A subset of healthy controls later developed hyperketonemia and were reclassified as a third health group. No significant differences in the fecal microbiome was observed, and only one difference in the rumen microbiome between healthy and hyperketonemic cows was detected.
Technical Abstract: Background: Many dairy cows experience a state of energy deficit as they transition from late gestation to early lactation. The aims of this study were to 1) determine if the development of hyperketonemia in early lactation dairy cows is indicated by their gut microbiome, and 2) to identify microbial features which may inform health status. We conducted a prospective nested case-control study in which cows were enrolled 14 to 7 days before calving and followed through their first 14 days in milk (DIM). Hyperketonemic cows (HYK, n = 10) were classified based on a blood Beta-hydroxybutyrate (BHB) concentration >= 1.2 mmol/L within their first 14 DIM. For each HYK cow, two non-HYK (CON, n = 20) cows were matched by parity and +- 3 DIM, with BHB < 1.2 mmol/L. Daily blood BHB measures were used to confirm CON cows maintained their healthy status; some CON cows displayed BHB >= 1.2 mmol/L after matching and these cows were reclassified as control-HYK (C-HYK, n = 9). Rumen and fecal samples were collected on the day of diagnosis or matching and subjected to 16S rRNA profiling. Results: No differences in taxa abundance, or alpha and beta diversity, were observed among CON, C-HYK, and HYK health groups for fecal microbiomes. Similar microbiome composition based on beta diversity analysis was detected for all health statuses, however the rumen microbiome of CON and HYK cows were found to be significantly different. Interestingly, highly similar microbiome composition was observed between C-HYK cow rumen and fecal microbiomes, suggesting that these animals which initially appear healthy with late onset of hyperketonemia were highly similar. These C-HYK cows had significantly lower abundance of Ruminococcus 2 in their rumen microbiome compared to CON and HYK groups. Multinomial regressions used to compute log-fold changes in microbial abundance relative to health status were not found to have predictive value, therefore were not useful to identify the role of certain microbial features in predicting health status. Conclusions: Lower relative abundance of Ruminococcus 2 in C-HYK cow rumens was observed, suggesting these cows may be less efficient at degrading cellulose although the mechanistic role of Ruminococcus spp. in rumen metabolism is not completely understood. Substantial differences in fecal or rumen microbiomes among cows experiencing different levels of energy deficit were not observed, suggesting that hyperketonemia may not be greatly influenced by gut microbial composition, and vice versa.