Minimization of rate of inbreeding for small populations with overlapping generations

We propose a method that minimizes the rate of inbreeding (DeltaF) for smal l unselected populations with overlapping generations and several reproduct ive age classes. It minimizes the increase in coancestry of parents and opt imizes the contribution of each selection candidate. The carrying capacity of the population is limited to a fixed number of animals per year. When su rvival rate equalled 100 %, only animals from the oldest age class were sel ected, which maximized the number of parents per generation, slowed down th e turnover of generations and minimized the increase of coancestry across s ublines. However, the population became split into sublines separated by ag e classes, which substantially increased inbreeding within sublines. Sublin es were prevented by a restriction of selecting at least one sire and one d am from the second-oldest age class, which resulted in an L times lower Del taF, where L equals the average generation interval of sires and dams. Mini mum coancestry mating resulted in lower levels of inbreeding than random ma ting, but DeltaF was approximately the same. For schemes where the oldest a nimals were selected, DeltaF increased by 18-52 % compared with the propose d method.