Relationships between fatty liver and fertility and some periparturient diseases in commercial Dutch dairy herds

Declining fertility in dairy cows is frequently suggested to arise from the occurrence of a more negative energy balance and/or the concomitant increa sed accumulation of triacylglycerol in the liver. Therefore, we performed a field study to assess the clinical effects of postpartum fatty liver in da iry cows on fertility and reproductive disease. Data were collected from 36 0 cows from nine dairy herds on fertility, diseases, and the liver triacylg lycerol content on two occasions during lactation: 6 to 17 days and 38 to 5 0 days postpartum. The mean concentration of triacylglycerol in the liver w as 54.6 mg/g from 6 to 17 days and 38.4 mg/g from 38 to 50 days postpartum. The probability of pregnancy was 30% lower for cows with higher contents o f triacylglycerol in the liver compared to the probability for cows with lo w liver triacylglycerol (P = 0.049). The probability of estrus was also 35% lower for the cows with high triacylglycerol in the liver. This resulted i n larger intervals between parturition and first heat and parturition and p regnancy for these cows. There was no effect observed on the first insemina tion conception rate. Given a certain level of triacylglycerol, recorded mi lk production had a positive effect on time to pregnancy. The incidences of endometritis, lochiometra and cystic ovarian follicles were not higher in cows with higher liver triacylglycerol contents. Endometritis was associate d with a lower first insemination conception rate and more days open (chi ( 2) = 4.26, P = 0.03 and T-test = -2.02, P= 0.04 respectively). We concluded that our results support the idea that differences in the negative energy balance or the accumulation of triacylglycerol in the liver of postpartum d airy cows affects fertility performance. The data also indicate that an inc rease in milk production has no negative impact on fertility as long as the amount of triacylglycerol in the liver remains the same. (C) 2000 by Elsev ier Science Inc.