Cytoplasmic line effects for birth weight and preweaning growth traits in the Asturiana de los Valles beef cattle breed

A total of 15,645 records of birth weight (BrW), weaning weight (WW) and average daily gain(ADG) from 6055 cows belonging to 2121 different dam lines were analyzed to quantify the contribution of cytoplasmic line (l) effects to phenotypic variance of preweaning growth traits in a sample of Asturiana de los Valles beef cattle breed. Only dam lines with 2 or more cows having performance records in the database were used. Bayesian estimates were obtained fitting eight different univariate and multivariate models defined depending on the inclusion or not of the permanent maternal environment (c) and the l effects. Univariate models that included both the c and the l effects had the best fit with data (assessed by computing the logarithm of the conditional predictive ordinate; logCPO) for BrW and ADG while for WW this was the case for the model that only included the c effect. For multivariate models, the best fit with data was obtained for the model that only included the c effect (logCPO= −245,899) while the second “better” model was that which only include the l effect value(logCPO=−241,108). In general, whatever the estimation model used, estimates of heritability for the direct (h2) and maternal (m2) genetic effects and the genetic correlation between them (ram) obtained in the current study for BrW were slightly higher (ram more negative)than the most recent estimates reported in the breed. However, this is not true for WW and ADG when multivariate estimation models include the l effect. In these cases, estimates of h2 and m2 forWWand ADG tend to be lower and ram less negative than those previously estimated. In conclusion, the cytoplasmic line may have a marginal effect on growth performance in beef cattle but not sufficient in magnitude to justify including the l effect in models in beef improvement schemes