Optimization of breeding population size for long-term breeding

A model for optimization of the long-term breeding population size by considering genetic gain, relatedness, time and cost components was developed for the optimum allocation of resources between the breeding and testing populations. The group coancestry and the average breeding value for the breeding population were merged into a joint index, known as group merit. The size of the breeding population was regarded optimal when the annual increase in group merit was maximized at a budget constraint. A study scenario with a balanced selection and parameters suitable to northerly conifers bred in a multipopulation design was applied. The optimum breeding population size ranged between 30 and 70. High heritability, more efficient breeding strategy, high additive variance at mature age, low annual budget, expensive testing method and a low value assigned to gene diversity favoured a small breeding population size.