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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Cell Wall Biology and Utilization Research » Research » Publications at this Location » Publication #412009
Research Project: Developing Strategies to Improve Dairy Cow Performance and Nutrient Use Efficiency with Nutrition, Genetics, and Microbiology

Location: Cell Wall Biology and Utilization Research

Title: Blood transcriptome and its microbial community in young claves with prolonged ruminal acidosis

Author
item LARSEN, ANNA - Oak Ridge Institute For Science And Education (ORISE)
item Li, Wenli

Submitted to: Ruminant Physiology International Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/14/2024
Publication Date: 8/26/2024
Citation: Larsen, A., Li, W. 2024. Blood transcriptome and its microbial changes in young calves with feed-induced ruminal acidosis [abstract]. International Symposium on Ruminant Physiology. Paper No. 74.

Interpretive Summary:

Technical Abstract: Subclinical ruminal acidosis (SARA) due to feeding fermentable feedstuffs during the weaning period is a significant digestive disorder in calves. In adult cattle, studies using diet-induced SARA models reported deleterious changes in the rumen and peripheral blood, including ruminal pH depression, damaged ruminal epithelium (RE), and increased concentration of bacterial lipopolysaccharides (LPS) in the blood stream. However, aside from measuring ruminal pH, early diagnostic tools for SARA are lacking. Here, using our established feed-induced SARA model, we investigated the blood transcriptome (BT) with whole transcriptome sequencing and its associated microbial communities using rRNA sequencing reads in young calves. Ten Holstein bull calves were randomly assigned to either acidosis-inducing (AC) or -blunting (Control) diets at birth until 17 weeks of age. Blood samples were collected at 8 and 16 weeks. Differentially expressed genes (DEGs; p = 0.05, fold change = 1.5, read count [RC] = 5) were identified using DEseq2, and gene ontology (GO) enrichment analysis was done with DAVID. Microbial taxa classification was done using Kraken2. At 8 weeks, 337 DEGs were identified in AC vs. Control. Of these, 143 were up-regulated and 194 were down-regulated in AC. Upregulated genes (UGs) in AC were enriched in molecular pathways related to glycoprotein synthesis and disulfide bond formation, both of which have reported roles in immunity, cellular repair, and inflammatory response. Downregulated genes (DGs) showed a GO enrichment in lyase activity, whose deficiency was previously reported in both human and mouse subjects with metabolic acidosis. At 16 weeks, 266 DEGs were identified in AC vs. Control, consisting of 144 UGs and 124 DGs. For UGs, GO enrichments in innate immunity and viral responses were identified. DGs in AC at both 8 and 16 weeks were associated with extracellular structures and functions, including signaling and secretion. Five microbial genera (average RC >10) showed abundance changes (p<0.01) at 16 weeks. Among these, Bacteroides, an LPS-producing bacterium, was the most abundant and showed a more than 10-fold increase in the AC group. Collectively, our study suggested that the impact of feed induced SARA can be captured by the BT as early as 8 weeks. Additionally, changes in molecular mechanisms related to blood cellular structure and immune responses might be part of the effect SARA elicits beyond traditionally investigated RE. Notably, the five microbial taxa we identified in the blood might be further developed into biomarkers to aid in early diagnosis, management, and prevention of feed-induced SARA in young calves.