Genetic parameter estimates of production traits of Angora goats in Argentina

The objective of this study was to estimate genetic parameters for fleece traits in an experimental Angora goat flock. The fleece traits analyzed in this study were: greasy fleece weight (GFW), average fiber diameter (AFD), percentage of medullated fiber (MF) and corrected greasy fleece weight (CGFW). Direct and maternal variance components and resulting heritabilities were estimated using an animal model and DFREML procedures on the first shearing. Six different animal models were fitted ranging from a simple model with animals as the only random effect to the most comprehensive model allowing for both genetic and environmental maternal effects and a genetic correlation between genetic direct and maternal effects. The models were tested by the Likelihood Ratio Test which indicated that the maternal effects (genetic and environmental) can be ignored. Direct heritabilities estimated with a single trait model were 0.26±0.06, 0.33±0.06, 0.10±0.04 and 0.22±0.06 for GFW, AFD, MF and CGFW, respectively. Genetic correlations were estimated with a multivariate model. The pattern of correlations showed that GFW was positively correlated with AFD and CGFW, 0.51 and 0.53 respectively and negatively correlated with MF −0.72. AFD was negatively correlated with MF and CGFW (−0.18 and −0.37, respectively) and MF was negatively correlated with CGFW −0.65. The repeatability estimates were based upon other files containing information on all shearings. The repeatabilities were 0.64, 0.70, 0.58 and 0.68 for GFW, AFD, MF and CGFW, respectively. Genetic parameters estimated in this study appear reliable and provide a better basis for the Argentina genetic Angora goat improvement program. The moderate heritability level for CGFW added to the negative genetic correlation with AFD may be an alternative solution for selection programs based on a single trait. The high levels of repeatability estimates confirm the benefits of the selection program based on objective measurements observed at the age of year.