EN
The aim of the study was to evaluate the influence of the milk yield of a milk cow on the length of its calving interval. The studies were carried out on 104 crossbred cows (Black-and White x HF). On the basis of the breeding data the length of calving interval (OMC) as well as the insemination index, number of milking days and the milk yield of consecutive lactations, were analyzed. Only cows having at least three consecutive lactations were studied. Milk yield data were divided into three groups: lower than 5000 kg of milk per lactation, between 5000 to 7000 kg and more than 7000 kg per lactation. The results indicate the significant influence of the milk yield and the consecutive lactation period on the length of OMC. It was noted that the greater milk yield observed the longer the interval of OMC was. Some reproductive traits that were mentioned before were not as satisfactory as we expected them to be for the studied herd. We assume that other factors like insemination failure can influence the length of OMC and milk yield, which is indicated by the high value of the insemination index.