A descriptive study of postpartum anoestrus in nine high-yielding dairy herd in Flanders

Fertility data derived from 3,108 lactation periods in nine high-yielding d airy herds in Flanders were analyzed to determine the incidence and importa nce of preservice postpartum anoestrus. In 1,291 (42%) of all lactation per iods studied, no heat was observed within 60 days after calving, Of the cow s observed to be in heat within the first 60 days after calving (n = 1,817) , 622 (34%) had to be examined during regular herd health visits because th ey had not been observed to be in heat at the time insemination should be p erformed. Hence, in total, 1,913 (62%) of all lactation periods were identi fied as having suffered from one or another kind of preservice postpartum a noestrus. Cows not observed in heat within 60 days after calving as well as cows suffering from cessation of cyclicity, both had a significant (P < 0. 001) increase in days open (26 and 24 days respectively) and a significantl y (P < 0.05) increased risk of being culled as compared with their normal h erdmates (Odds Ratio: 1.41 and 1.44 respectively). There was a significant (P < 0.001) variation among the herds in the lactational incidence rate (LI R) both for cows not observed in heat during the first 60 days after calvin g and for cows with cessation of cyclicity, the former ranging from 21% to 67%, and the latter from 14 to 48% among the herds. Besides significant her d influences, the season of calving was also of major importance. The LLR f or cows not observed. In dairy herds, and explain the need for further inve stigation of this problem with a view to taking preventive measures.