Transition dairy cows show blood alterations in innate immunity ahead of occurrence of retained placenta
Retained placenta (RP) is defined as failure to expel the fetal membranes from the uterus within 24 h after calving. The incidence of RP in a dairy farm, under normal conditions, averages 7-10%. RP results in increased days open, calving to first heat interval, services per conception, and days from calving to first service. The etiopathology of RP is not known and it is of interest to search for contributing factors that induce the disease. The objective of this investigation was to evaluate whether there are alterations in blood variables related to innate immunity and carbohydrate and lipid metabolism in transition dairy cows with placental retention. One hundred multiparous Holstein dairy cows were involved in the study. Seventeen blood samples were collected from the coccygeal vein during the -8 to +8 wk around parturition, once per week before the morning feeding. Six healthy control cows (CTR) and 6 cows with RP were selected and serum samples collected at -8, -4, time of diagnosis of disease, and +4 wks relative to parturition were analyzed for lactate, non-esterified fatty acids (NEFA), beta-hydroxybutiric acid (BHBA), interleukin-1 (IL-1), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-a ), haptoglobin (Hp), serum amyloid A (SAA) and lipopolysaccharide binding protein (LBP). In addition, health status, feed intake, rectal temperature, and milk yield data were monitored for each cow during the whole experimental period. Results revealed that cows with RP had greater concentrations of serum lactate, IL-1, TNF-a, SAA, and LBP in comparison with CTR. Intriguingly, elevated concentrations of all five variables were observed at -8 and -4 wks before the occurrence of RP compared to CTR cows. Cows with RP also had lower feed intake and milk production vs control animals. However milk composition was not affected by RP. Overall results suggest that serum lactate, IL-1, TNF-a, SAA, and LBP can be used, in the future, to indicate cows that might have health issues during the transition period. More research is warranted to better understand the agent(s) that contribute(s) to RP in transition dairy cows.
Keywords: Transition dairy cows, Retained placenta, Innate immunity