The effects of a post partum injection of prostaglandin F2α on return to oestrus and pregnancy rates in dairy cows

The interval from calving to conception is unnecessarily long in dairy cows. Post partum administration of prostaglandin F(2)alpha can reduce the calving to conception interval, but it is not known whether this is due to advanced return to oestrus, increased oestrus intensity and/or increased pregnancy rates. In two experiments, the treatment of dairy cows with prostaglandin F(2)alpha 21 days Post partum reduced the interval to first oestrus and first service by about 10 days. The intensity of oestrus was not affected. Pregnancy rates to first service were increased from (on average) 60 to 80%, and the number of services/conception was reduced from 2.0 to 1.3.