Minimizing inbreeding by managing genetic contributions across generations

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Sanchez, Léopoldo | Bijma, Piter | Woolliams, John

Edité par CCSD ; Oxford University Press -

International audience. Here we present the strategy that achieves the lowest possible rate of inbreeding ({Delta}F) for a population with unequal numbers of sires and dams with random mating. This new strategy results in a {Delta}F as much as 10% lower than previously achieved. A simple and efficient approach to reducing inbreeding in small populations with sexes of unequal census number is to impose a breeding structure where parental success is controlled in each generation. This approach led to the development of strategies for selecting replacements each generation that were based upon parentage, e.g., a son replacing its sire. This study extends these strategies to a multigeneration round robin scheme where genetic contributions of ancestors to descendants are managed to remove all uncertainties about breeding roles over generations; i.e., male descendants are distributed as equally as possible among dams. In doing so, the sampling variance of genetic contributions within each breeding category is eliminated and consequently {Delta}F is minimized. Using the concept of long-term genetic contributions, the asymptotic {Delta}F of the new strategy for random mating, M sires and d dams per sire, is {phi}/(12M), where {phi} = [1 + 2(1/4)d]. Predictions were validated using Monte Carlo simulations. The scheme was shown to achieve the lowest possible {Delta}F using pedigree alone and showed that further reductions in {Delta}F below that obtained from random mating arise from preferential mating of relatives and not from their avoidance.

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