Environmental effects, population genetic parameters, breeding value, phenotypic and genetic trend for age at first calving of Limousin cows/Populációgenetikai paraméterek, tenyészértekek, fenotípusos és genetikai trendek limousin tehenek elso ellesi életkorara

Some environmental effects, population genetic parameters, breeding value of Limousin breeding bulls, also phenotypic and genetic trends in the age at first calving (AFC) of cows between 1992 and 2013 were estimated. Data were served by the Limousin and Blonde d'Aquitaine Breeders Association, in Hungary. The study was extended to three herds and 1157 cows. GLM method was used for the study of different effects, the BLUP animal model for estimation of population genetic parameters and breeding values (BV), and one-way linear regression analysis for trend calculations. The overall mean value of the AFC was estimated to be 34.7[+ or -]0.4 months. The contribution of the evaluated factors to the phenotype was as follows: herd 73.51%, birth year of cow 13.02%, sire 6.74%, birth season of cow 1.62%. The heritability of AFC proved to be low ([h.sup.2] = 0.08[+ or -]0.07 and [h.sup.2] = 0.01[+ or -]0.04). There were relatively small differences in the estimated BV of the studied sires for the AFC. Based on the phenotypic trend calculation, the AFC of cows decreased by an average of 0.33 months per year, however no significant change was found in the genetic trend during the study period.