Circadian disruption decreases gluconeogenic flux in late-gestation, nonlactating dairy cows

Cattle exposed to shifts in light-dark phases during late pregnancy develop hypoglycemia and insulin resistance. Our objective was investigate if differences liver carbon flux for gluconeogenesis were driving circadian-disrupted metabolic alterations glucose homeostasis, relate changes hepatic gene expression. We hypothesized circadian disruption would decrease synthesis. Milking ceased late-gestation Holstein cows (n = 8) at 60 d before expected calving (BEC), animals assigned either a control 4) or phase-shifted (PS; n group. From 35 21 BEC both groups of 16 h light 8 dark, but the PS, shifted forward 6 every 3 d. On BEC, biopsies collected, subdivided, incubated 1.0 mM [U-13C] propionate 2 h. Total RNA isolated from separate sample used RNA-sequencing analysis. Postincubation 13C mass isotopologue distribution determined aspartate, serine, alanine, glutamate calculate ratios. Enrichment serine enrichment aspartate ratio (eSer:eAsp) lower PS (0.75 ± 0.02) compared with (0.81 0.04), indicating reduction toward animals. eSer:eAsp negatively correlated propionyl-CoA carboxylase (PCCB; r −0.79) succinate dehydrogenase subunit D (SDHD; −0.82). These relationships indicate that when dairy cattle are gestation, is preferentially energy rather than gluconeogenesis.