Mate Selection Accounting for Connectedness

Mate selection refers to selection and mating decisions being performed simultaneously. This one step approach is suitable to accommodate different key issues faced by animal breeders (Kinghorn et al., 1999). To implement mate selection an objective function needs to be defined and maximized (Shepherd and Kinghorn, 1999). Kinghorn et al. (1999), for example, applied mate selection maximizing a function considering expected merit and inbreeding coefficient of the future progeny and coancestry among selected parents. This strategy, compared with procedures that adopt the selection and mating decisions in separate steps, permitted a higher genetic progress and a better control of the inbreeding. Degree of connectedness among contemporary groups (CGs) is another key issue that could be considered in mate selection, aiming to increase accuracy of EBVs an their contrasts. Kennedy and Trus (1993) argued that the most appropriate measure of connectedness is the average prediction error variance of differences (PEVd) in EBVs of animals from different groups. This statistic is, however, extremely time consuming and usually not feasible for practical applications. Roso et al. (2004) observed that the number of genetic links among CGs is a good, and ease to calculate, measure to predict PEVd. This study was carried out aiming to develop a program to perform mate selection, and to empirically evaluate the consequences of considering different measures of connectedness in the optimization of the objective functions.