Zaleznosc miedzy wynikami pierwszej 100-dniowej laktacji pierwiastek a wydajnoscia zyciowa w stadzie kr�w holsztynsko-fryzyjskich

Abstract

The aim of this study was to identify the relationship between the lifetime performance of cows and their performance during the first 100 days of lactation. The studied material consisted of breeding documentation for 2,347 Holstein-Friesian cows, that were used for milk production between 1995 and 2010, in the Pedigree Breeding Centre in Osieciny. Such parameters as milk yield, fat (kg, %) and protein content (kg, %) were taken into consideration while analysing the results for the first 100 days of lactation and the lifetime milk performance. The study included only animals that had already been culled. Results indicate that the factors affecting the primiparas milk production during the 100-day lactation are as follows: herd, year and season of first calving as well as the age at first calving. It was proven that the sources of variation in the lifetime performance, in terms of the milk yield, fat and protein content, were: herd, year of first calving, age at first calving and the level of milk yield during the first 100 days of primiparas lactation. It was observed that the season of first calving did not significantly affect milk performance traits throughout the cows productive life. The calculated correlation coefficients, mainly of weak relationship between levels of the lifetime performance and the 100-day performance, showed a moderate positive correlation between the percentage content of fat and protein in milk in both periods.