CONICET | Buscador de Institutos y Recursos Humanos

The health problems detected during peripartum period could be due to impaired leucocyte activity related to systemic factors such as hormones and metabolic components highly modified in this period. Throughout lactation period in dairy cows, little information is available about reactivity of phagocytic cells. The aim of this study was to analyze the phagocytic activity (PA) of monocytes/macrophages throughout lactation and their implication on the index of days to conception considering the hormonal and metabolic context. Blood samples were collected at different postpartum days. Cows were grouped according to thelength of days to conception period: fewer (83±6 days) and greater (128±32) days. All procedures were approved by the Ethics Committee (FCV-UNL). Plasmatic concentrations of cortisol, estrogen, progesterone, non-esterified fatty acids and glucose were measured. The differential leukocyte counts were performed by blood smears. The PA and mean fluorescence intensity (MFI) of monocytes/macrophages were determined by flow cytometry. A Generalized Linear Model with repeated measures was used to analyze different effect on leukocyte count and immunoreactivity. Kaplan?Meier test was used to evaluate the effect of PA and MFI on the delay to conception time. The results showed that the hormonal and metabolites levels there were no significant effects on the counts of monocytes/macrophages over time. However, estradiol and glucose concentrations had a significant effect on the PA and MFI. Finally, cows with lower MFI were pregnant earlier than those with higher MFI. These results suggest a relation between the reactivity of monocytes/macrophages and the delay to conception time.