Impacts of parturition and body condition score on glucose uptake capacity of bovine monocyte subsets
The peripartal period of dairy cows is associated with a higher incidence of infectious diseases like mastitis or metritis, particularly in high-yielding animals. The onset of lactation induces a negative energy balance and a shift of glucose distribution towards the udder. Glucose is used as primary fuel by monocytes which give rise to macrophages, key cells in the defense against pathogens. The aim of this study was to analyze whether animals with high or low body condition score (BCS) differ in composition and glucose uptake capacities of bovine monocyte subsets. Blood samples were taken from 27 dairy cows starting 42 days before parturition until day 56 after parturition. The cows were allocated to two groups according to their BCS. A feeding regime was applied, in which the BCS high group received higher amounts of concentrate before parturition and concentrate feeding was more restricted in the BCS high group after parturition compared with the BCS low group, to promote postpartal lipolysis and enhance negative energy balance in the BCS high group. Blood cell counts of classical (cM), intermediate (intM) and nonclassical monocytes (ncM) were increased at day 7 after calving. In the BCS low group intM numbers were significantly higher compared to the BCS high group at day 7 after parturition. Within the BCS low group cows suffering from mastitis or metritis showed significantly higher numbers of cM, intM and ncM at day 7 after parturition. Classical monocytes and intM showed similar glucose uptake capacities while values for ncM were significantly lower. Compared with antepartal capacities and irrespective of BCS and postpartal mastitis or metritis, glucose uptake of all monocyte subsets decreased after parturition. In conclusion, whereas glucose uptake capacity of bovine monocyte subsets is altered by parturition, it is not linked to the energy supply of the animals or to postpartal infectious diseases.