Analysis of the relationship of blood metabolites with white blood cells in periparturient dairy cattle

relationship of blood metabolites with white blood cells

Abstract

Periparturient dairy cattle are susceptible to metabolic disease due to immense physiological stress caused by calving and the onset of lactation. Susceptibility to disease is related to the cow’s ability to maintain metabolic homeostasis and mount a proper immune response, despite high demand for glucose to support fetal growth and milk synthesis, and as a fuel for increased circulating levels of white blood cells (WBC). This study was conducted to determine if there was a correlation among white blood cell percentages, blood glucose, and the levels of the ketone betahydroxybutyrate (BHBA) on the days immediately around parturition, and to determine if the variables exhibited circadian rhythms. We hypothesized that glucose levels would vary inversely with WBC, and BHBA levels would vary directly with glucose levels. Blood was sampled from the tail vein of multiparous Holstein cows (n=12) at 0600 from 4 days prepartum to 4 days postpartum, and every 4 hr over a 24-hr period (n=6) starting at 0600 on postpartum day 3.  Blood glucose and BHBA levels were measured using a CentriVet™, and WBC percentage was calculated by measuring packed cell volume. Glucose was higher (p<0.05) before (73.77 mg/dL±4.65) versus after (68.85 mg/dL±6.15) parturition, whereas BHBA was higher (p<0.05) after calving (0.53 mg/dL±0.39) versus before (0.20 mg/dL±0.16). WBC percentages did not vary significantly by day. None of the variables exhibited circadian rhythms according to cosinor analysis. Pearson’s correlation analysis revealed an inverse relationship (r= -0.23, p=0.04) between glucose and BHBA levels, and a direct relationship between WBC percentage and BHBA (r= 0.25, p=0.03).  This finding supported our hypothesis, and suggests that immune responses during the periparturient period may affect metabolic homeostasis.