Cystic ovarian disease in Dutch dairy cattle, I. Incidence, risk factors and consequences

Abstract

The aim of this study was to describe incidence, risk factors and consequences of cystic ovarian disease (COD) on 21 farms in the central part of the Netherlands. Special regard was given to milk production as a risk factor and/or a consequence of COD. Data on production, reproduction, disease occurrence and culling were collected in the course of a Herd Health program. The overall cumulative incidence of COD was 0.099. and ranged from 0.04 to 0.17 per farm. Important risk factors for COD were standard cow production and parity. There was some further effect of season of calving, ketosis and dystocia but these effects were not significant. Results regarding the consequences of COD showed that the calving interval, the dry period and the lactation period were respectively 45, 5 and 49 days longer and the total milk yield was 1222 kg more in cows with COD. In addition, the milk production per day of lactation was only 0.3 kg higher in the COD animals ( P = 0.24). The survival curve showed that relatively more cows without COD than with COD were culled the first 260 days after the (simulated) occurrence of COD. After 260 days the opposite effect was seen. The results are discussed with attention to expected costs of COD and the possible pathophysiologic processes underlying the disorder.