Optimization of selection and mating schemes in closed broiler lines

Abstract

Minimum coancestry mating (MC) is a simple mating system to reduce inbreeding in populations, in which matings are allocated so as to minimize the average inbreeding coefficient of progeny. This system was compared with random mating (RM) in simulated broiler lines. The population structure and genetic parameters were determined on the basis of an existing broiler line. Comparison of mating systems was made under two selection methods. The first method (DIS) was based on selection index for achieving desired genetic gains. In the second method (LPS), a combination of the family index and linear programming technique was applied to obtain the desired genetic gains. The selected traits were body weight at 6 weeks of both sexes and age at sexual maturity of hen. Four schemes by all the possible combinations of selection and mating methods (DIS + RM, DIS + MC, LPS + RM and LPS + MC) were compared in terms of genetic gains and inbreeding during 15 generations of selection and mating. The results obtained are summarized as follows: (i) the four schemes produced similar genetic gains averaged over replicates; (ii) the variations of genetic gains under LPS + RM and LPS + MC schemes were much smaller than under DIS + RM and DIS + MC schemes; (iii) irrespective of the selection methods, MC reduced the average inbreeding coefficients to about 80% of RM and; (iv) the inbreeding coefficients of individuals in the schemes with RM were distributed in a wide range, while the inbreeding coefficients in the schemes with MC showed a high uniformity. From these results, the LPS + MC scheme was recommended as a selection and mating strategy in closed broiler lines.