Managing genetic resources in selected and conserved populations.

Managing the rate of inbreeding (ΔF) provides a general framework for managing genetic resources in farmed breeding populations. Methods for managing ΔF have been developed over the last five years and they allow the attainment of the greatest expected genetic progress while restricting at the same time the increase in inbreeding. This is achieved by optimising the contribution that each candidate for selection must have to produce the next generation. The methods take into account all available performance and pedigree information and use Best Linear Unbiased Prediction (BLUP) estimates as a predictor of merit. Importantly, these tools give at least equal, but more often more gain than traditional selection based on truncation of BLUP estimated breeding values when compared at the same ΔF. Deterministic predictions for the expected gain obtained with optimised selection with ΔF restricted are now available. The optimisation tool can be also applied in a conservation context to minimise ΔF with restrictions to avoid loss in performance in valuable traits. Information on known quantitative trait loci or on markers linked to them can be incorporated into the optimisation process to further increase selection response. Molecular genetic information can also be incorporated into these tools to increase the precision of genetic relationships between individuals and to manage ΔF at specific positions or genome regions.