Genetic analysis of values, trends and relations between conformation and milk traits in Polish Holstein-Friesian cows
In the work presented an analysis was performed of the genetic values of conformation traits in cows and their relations with the genetic value of dairy traits, basing on dairy performance (milk, fat and protein yield) and conformation data, obtained for Polish Holstein-Friesian cows of the Black-and-White variety, born between year 2001 and 2004, and maintained in 21 herds in the region of Wielkopolska (central Poland). The genetic values for the data analysed were estimated using the BLUP method and a mixed model. For the traits analysed a genetic trend was estimated as well as genetic correlations between the dairy and conformation traits. The population analysed was divided depending on year of birth and production level. The results obtained show a systematic increase in the traits analysed (positive genetic trends), both for the dairy and for conformation traits (with the exception of temperament). The highest genetic correlations between dairy and conformation traits were obtained for the udder, temperament and dairy type, while the lowest for height at sacrum and calibre. The analysis of the genetic value of conformation traits in cows of different dairy production genetic values indicated that the highest results were obtained for the group of animals with the highest genetic dairy production value. In turn, the analysis of the genetic value of traits of cows born in different years did not show statistically significant differences, with the exception of height in the youngest group.