Relationships between plasma insulin-like growth factor-1 and insulin concentrations in multiparous dairy cows with cytological endometritis

Cytological endometritis (CYTO) is a uterine inflammation characterised by the percentage of polymorphonuclear neutrophils in endometrial cytology. This observational study evaluated the association of blood plasma insulin-like growth factor-1 (IGF-1) and insulin concentrations at -2 weeks prepartum, +1 week and +3 weeks postpartum with the development of CYTO in 119 multiparous Holstein cows. Overall CYTO prevalence was 30.3 per cent. Multivariable logistic regression model revealed the odds of developing CYTO were 3.54 times (P=0.018) greater in cows with week -2 prepartum IGF-1 concentrations less than 74.6 ng/ml and 4.41 times (P=0.004) higher in cows with week +1 postpartum IGF-1 concentrations less than 13.2 ng/ml than the odds of this health outcome in cows with IGF-1 concentrations at least 74.6 and13.2 ng/ml, respectively. Additionally, cows with body condition score (BCS) up to 2.75 at week -2 prepartum and cows experiencing calving-related disorders and/or ill health had higher risk for CYTO compared with cows with BCS=3.50-3.75 (OR=6.8, P=0.049) and cows without health complications (OR=3.1, P=0.030). Insulin was not a significant predictor for CYTO in the model. Our findings provide further evidence that reduced dairy cow fertility associated with low plasma concentrations of IGF-1 is in part mediated through the inflammatory status of the uterus.