Genetic Parameters Of The Type Traits Of Holstein-Friesian Primiparous Dairy Cows

Jankovic D., B. Markovic, R. Djedovic, S. Trivunovic, M. Saran (2021). Genetic parameters of the type traits of Holstein-Friesian primiparous dairy cows. -Genetika, Vol 53, No.2, 533-544. The aim of this study was to determine the level and variability of type traits in primiparous Holstein-Friesian cows, as well as to assess the additive genetic variance of type traits and heritability coefficients. The research was conducted on a data set of linearly evaluated primiparous Holstein-Friesian cows, which is ceded by the Main dairy cattle breed organization in the Province of Vojvodina, which is a unit of the Department of Animal Science, at the Faculty of Agriculture in Novi Sad. Data of 24226 primiparous Holstein-Friesian cows, refer to the period 2012-2015, were analysed. The phenotypic variability of the type traits, as well as effects of systemic factors affecting these traits, were analyzed using standard statistical methods in the Statistica software 13.2, and the general linear model (GLM). A Statistically highly significant effect for most of the type traits had the farm size, interaction of the year and the season of evaluation, age at linear evaluation, lactation stage and a genetic group formed by the year and country of bull/sires birth. The total type traits score (final score), which represents an evaluation of the overall primiparous cow exterior, is calculated for the 24226 linearly evaluated primiparous cows. Estimation of variance components and heritability coefficient calculation is done in the software package WOMBAT. Heritability coefficient values for the primiparous cow's type traits in the Province of Vojvodina were low to middle, ranged from 0.08 for the rear legs -side view up to 0.38 for the stature. Due to the fact that the value of the heritability coefficient depends on the variability of the traits and previous selection, lower heritability may be a consequence of the low genetic variability, or, a higher degree of variability which is a consequence of the effect of the systematic factors. Heritability coefficients indicate a genetic variability of the type traits, and its evaluation is important for the breeding value estimation for the type traits.