Additive genetic variance and covariance in some reproduetive disorders in Hungarian Holstein Friesian using multi-trait animal model
Abstract. Relationships between some reproduetive disorders in the first 3 lactations of Holstein Friesian cows were investigated for 1886 lactation records. Multiple-trait maximum likelihood procedure which included sire cow within sire as random effect and herd, parity, month and year of calving as fixed effects was used to estimate heritabilities and repeatabilities for the studied traits. Abortion within 60 days, retained placenta, ovarian cysts calving difficulty, dystocia, mastitis, and calving type were coded as 0 and 1 for heritability and repeatability estimations. Pooled and separate analysis were applied on the first 3 lactations. Abortion within 60 days retained placenta, ovarian cysts, calving difficulty, dystocia, mastitis, abortion no. and calving type had moderate heritability estimates which ranged from 0.15 to 0.24. Low heritability estimates and a weak sire variance component were obtained for milk fever. The most frequent disorder traits were mastitis, milk fever abortion no calving type and calving difficulty (0.37 to 0.72). Up word trend of heritability estimates with advancing order of lactation was observed for mastitis, abortion within 60 days, and abortion no. while heritability estimates for calving type, calving difficulty and dystocia had a back word trend. These results help in determining the suitable age of selection. Additive genetic variances and covariances among the studied traits have indicated reducing incidence rates if selection index procedure used in this filed. Strong negative genetic correlation between milk fever and abortion no. (−0.429) while negative phenotypic correlations between all studied traits were not more than −0.120 which was estimated for calving difficulty and abortion no.