A relationship between production and reproduction traits in cows of Czech Pied cattle

The purpose of the paper was to analyse the effect of the level of milk yield and breeding value on reproduction of Czech pied cows. In the study of cows that calved in the period 1999-2001 the results for 41 357 cows from the central database were used analytically. The study was focused on the following traits: breeding value of the father of the cow for kg of milk, breeding value of the mother of the cow for kg of milk, the cow's milk yield in the 1st to the 3rd lactation, and reproduction traits after the 1st and 2nd calving. To determine the effect of the breeding value of the father or mother of the cow on reproduction traits of daughters the test cows were divided into 3 groups depending on the BV of the parents. The results were processed by multifactor analysis of variance using the CORR and GLM procedures of the SAS statistical program, v. 8.1., and the model with fixed effects for the calculation itself. The results of the study show a negative correlation between the level of the milk yield of cows and their reproduction. It may be stated that the increased milk yield decreases reproduction traits characterised by the extension of days open and calving interval. The estimated correlation between the milk yield and the days open was r = 0.38 for milk yield, r = 0.32 for fat yield, and r = 0.25 for protein yield. A similar correlation between the level of milk yield and the days open was also found in other calving intervals.