Optimierung von Zuchtstrukturen einer Zweilinienkreuzung – Eine Monte-Carlo Studie

Abstract. Title of the paper: Optimization of the population structure for a two-line crossbreeding scheme – a Monte-Carlo study
A stochastic simulation was used to optimize the population structure in a two-line crossbreeding system under non-additive gene models. For different fixed test capacities, given number of offspring per dam and varying degrees of dominance the optimum number of selected sires was calculated. As criterions of the optimization the cumulative selection response on generation 10, the corresponding standard error of the response and the development of the inbreeding in the purebreds were used. If the trait was controlled by loci with partial and complete dominance, than the optimal number of selected sires was between 8 and 12 for given test capacities of 2304, 1152 and 1536 animals per generation and per the sire line. In the case of overdominance the number of selected sires increased on 24 to 48. Additionally, the level of the selection response in the three populations was affected by the difference of the allele frequencies in the initial generation and the economic weights of the additive purebred and crossbred effects. Under partial and complete dominance with corresponding purebred-crossbred genetic correlations of high and moderate level only small extra benefits were obtained from including crossbred information over pure line information.