Phenotype and genetic correlation between milk yield traits in first three consecutive lactations of black and white cows

Abstract

In order to conduct selection on the larger number of traits, that are significant from the economic aspect, it is necessary to know the direction and strength of correlation between observed traits. In this research average values and variability of the most significant milk yield traits as well as coefficients of genetic and phenotype correlations are described. This research was conducted on 1369 cows that had finished their first three lactations in period from 2006 to 2010th year. Cattle were bread at 7 farms of Agricultural Corporation Belgrade and they are descendants of 29 bulls. The following traits were researched: milk yield, milk fat content and milk fat yield. Obtained genetic correlation values in this research were from -0.375 between milk fat content in entire lactation and milk yield in standard lactation, up to 0.998 for milk fat content in entire and standard lactation. Obtained phenotype correlation values were from -0.207 between milk yield in standard lactation and milk fat content in entire lactation up to 0.958 between milk yield and milk fat content in entire lactation.

U cilju sprovođenja selekcije na veći broj osobina, koje imaju primarni značaj sa ekonomskog aspekta proizvodnje mleka, neophodno je poznavanje smera i jačine povezanosti između osobina. U radu su prikazane prosečne vrednosti i varijabilnost najvažnijih osobina mlečnosti, kao i koeficijenti fenotipskih i genetskih korelacija. Istraživanjem je obuhvaćeno 1369 grla koja su imala zaključene prve tri laktacije u periodu od 2006. do 2010. godine. Grla su gajena na 7 farmi Poljoprivredne korporacije Beograd i potomci su 29 bikova-očeva. Istraživanjem su obuhvaćene sledeće osobine mlečnosti: prinos mleka, sadržaj mlečne masti i prinos mlečne masti. Vrednosti koeficijenata fenotipskih korelacija imali su vrednosti od - 0.207 između prinosa mleka u standardnoj laktaciji i sadržaja mlečne masti u celoj laktaciji, do 0.958 između prinosa mleka i prinosa mlečne masti u celoj laktaciji. Vrednosti genetskih korelacija utvrđeni u istraživanju imali su vrednosti od -0.375 između sadržaja mlečne masti u celoj laktaciji i prinosa mleka u standardnoj laktaciji, do 0.998 za sadržaj mlečne masti u celoj i standardnoj laktaciji.