Project description:In dairy cows, administration of high dosages of niacin (NA) was found to cause anti-lipolytic effects, which are mediated by the NA receptor hydroxyl-carboxylic acid receptor 2 (HCAR2) in white adipose tissue (WAT), and thereby to an altered hepatic lipid metabolism. However, almost no attention has been paid to possible direct effects of NA in cattle liver, despite showing that HCAR2 is expressed also in the liver of cattle and is even more abundant than in WAT. Due to this, we hypothesized that feeding of rumen-protected NA to dairy cows influences critical metabolic and/or signaling pathways in the liver through inducing changes in the hepatic transcriptome. In order to identify these pathways, we applied genome-wide transcript profiling in liver biopsies obtained at 1 wk postpartum (p.p.) from dairy cows of a recent study (Zeitz et al., 2018) which were fed a total mixed ration without (control group) or with rumen-protected NA from 21 d before calving until 3 wk p.p. Hepatic transcript profiling revealed that a total of 487 transcripts were differentially expressed [filter criteria fold change (FC) > 1.2 or FC < -1.2 and P < 0.05] in the liver at 1 wk p.p. between cows fed NA and control cows. Substantially more transcripts were down-regulated (n = 338), while only 149 transcripts were up-regulated by NA in the liver of cows. Gene set enrichment analysis (GSEA) for the up-regulated transcripts revealed that the most enriched gene ontology (GO) biological process terms were exclusively related to immune processes, such as leukocyte differentiation, immune system process, leukocyte differentiation, activation of immune response and acute inflammatory response. In line with this, the plasma concentration of the acute phase protein haptoglobin tended to be increased in dairy cows fed rumen-protected NA compared to control cows (P < 0.1). GSEA of the down-regulated transcripts showed that the most enriched biological process terms were related to metabolic processes, such as cellular metabolic process, small molecule metabolic process, lipid catabolic process, organic cyclic compound metabolic process, small molecule biosynthetic process and cellular lipid catabolic process. In conclusion, hepatic transcriptome analysis shows that rumen-protected NA induces genes which are involved mainly in immune processes including acute phase response and stress response in dairy cows at wk 1 p.p. These findings indicate that supplementation of rumen-protected NA to dairy cows in the periparturient period may induce or amplify the systemic inflammation-like condition which is typically observed in the liver of high-yielding dairy cows in the p.p. period.

Project description:BackgroundPersistent productivity and productive lifespan determine the lifetime output of dairy cows and influence overall herd profitability. The composition and metabolic activity of the gastrointestinal microbiota of dairy cows influence persistent productivity. However, the processes by which host-microbiome crosstalk drives dairy cow persistent productivity remain unclear. Therefore, we performed an integrative comparative analysis of rumen and rectum metagenomes and metabolomes, together with serum and milk metabolomes, in long-lived dairy cows that exhibited divergent persistent productivity levels to elucidate the potential mechanisms that underpin modulation of persistent productivity by the rumen and rectum microbiota. ResultsSerum alanine aminotransferase (ALT), alkaline phosphatase (ALP), total cholesterol (TC), and high-density and low-density lipoprotein cholesterol (HDL-C and LDL-C) levels in long-lived dairy cows were positively correlated with milk yield (MY) and elevated in long-lived high-yielding (LH) dairy cows, whereas insulin (INS) and glucagon (GCG) were negatively correlated with MY and higher in long-lived low-yielding (LL) dairy cows. Rumen propionate level was elevated in LH group, but rectum fermentation parameters and rumen and rectum microbiota diversity showed no significant differences between LH and LL cows. The rumen microbiome, in LH cows upregulated pathways involved in amino acid, cofactor, and vitamin metabolism. LH cows’ rumen and rectum microbial interaction networks exhibited dependence on key nodes and streamlined inter-node connectivity that enhanced local functional synergy, with robustness, cohesion, and vulnerability levels similar to LL cows. The rumen Acidaminococcaceae bacterium and rectum Parabacteroides sp. exerted a positive effect on MY via microbiota-host co-metabolism of the purine metabolites guanosine and D-ribose-1-phosphate. Furthermore, the specific rumen microbiome module enhanced the levels of circulating eicosapentaenoic acid (EPA), thereby promoting the synthesis of Pe(20:5/0:0) in milk, which positively impacted MY. ConclusionsThe rumen and rectum microbiota positively influence production levels of long-lived dairy cows via microbiota and host co-metabolites of purine metabolites. Additionally, rumen microbiota improves production levels by enhancing host synthesis of EPA through the modulation of α-linolenic acid metabolism. The study reveals the potential role of rumen and rectum microbiota in regulating productivity of cows with sustained production capacity, providing insights for nutritional management strategies aimed at improving the health status and persistent production capacity of dairy cows.

Project description:BackgroundPersistent productivity and productive lifespan determine the lifetime output of dairy cows and influence overall herd profitability. The composition and metabolic activity of the gastrointestinal microbiota of dairy cows influence persistent productivity. However, the processes by which host-microbiome crosstalk drives dairy cow persistent productivity remain unclear. Therefore, we performed an integrative comparative analysis of rumen and rectum metagenomes and metabolomes, together with serum and milk metabolomes, in long-lived dairy cows that exhibited divergent persistent productivity levels to elucidate the potential mechanisms that underpin modulation of persistent productivity by the rumen and rectum microbiota. ResultsSerum alanine aminotransferase (ALT), alkaline phosphatase (ALP), total cholesterol (TC), and high-density and low-density lipoprotein cholesterol (HDL-C and LDL-C) levels in long-lived dairy cows were positively correlated with milk yield (MY) and elevated in long-lived high-yielding (LH) dairy cows, whereas insulin (INS) and glucagon (GCG) were negatively correlated with MY and higher in long-lived low-yielding (LL) dairy cows. Rumen propionate level was elevated in LH group, but rectum fermentation parameters and rumen and rectum microbiota diversity showed no significant differences between LH and LL cows. The rumen microbiome, in LH cows upregulated pathways involved in amino acid, cofactor, and vitamin metabolism. LH cows’ rumen and rectum microbial interaction networks exhibited dependence on key nodes and streamlined inter-node connectivity that enhanced local functional synergy, with robustness, cohesion, and vulnerability levels similar to LL cows. The rumen Acidaminococcaceae bacterium and rectum Parabacteroides sp. exerted a positive effect on MY via microbiota-host co-metabolism of the purine metabolites guanosine and D-ribose-1-phosphate. Furthermore, the specific rumen microbiome module enhanced the levels of circulating eicosapentaenoic acid (EPA), thereby promoting the synthesis of Pe(20:5/0:0) in milk, which positively impacted MY. ConclusionsThe rumen and rectum microbiota positively influence production levels of long-lived dairy cows via microbiota and host co-metabolites of purine metabolites. Additionally, rumen microbiota improves production levels by enhancing host synthesis of EPA through the modulation of α-linolenic acid metabolism. The study reveals the potential role of rumen and rectum microbiota in regulating productivity of cows with sustained production capacity, providing insights for nutritional management strategies aimed at improving the health status and persistent production capacity of dairy cows.

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