Bayesian estimates of genetic parameters for cystic ovarian disease, displaced abomasum and foot and leg diseases in Iranian Holsteins via Gibbs sampling

Abstract

SUMMARYThe objective of the current study was to estimate heritability and genetic correlations between cystic ovarian disease (COD), foot and leg diseases (FLD) and displaced abomasum (DA) within the first three lactations of Holstein dairy cows. The 57 301 lactation records of dairy cows on 20 large dairy herds in Iran between January 2005 and June 2009 were analysed with three-trait threshold animal models, using Gibbs sampling methodology. The final model included the fixed class effects of herd-year, season of calving, the linear covariate effect of age at calving and additive direct genetic effect of animal. Posterior means of heritability in first, second and third lactations were 0·15, 0·18 and 0·22, respectively, for FLD; 0·09, 0·11, and 0·13 for COD; 0·05, 0·06, and 0·08 for DA. Posterior means of genetic correlations between diseases were low (from 0·03 to 0·14), within lactations; the largest estimates were for FLD and DA, and the lowest involved FLD and COD. Positive genetic correlations between diseases suggest that some general disease resistance factor with a genetic component exists. The results of the present study indicated the importance of health traits for considering in the selection index of Iranian Holstein dairy cows.