Selection and mating strategies risks and rewards

Abstract

Best Linear Unbiassed Prediction provides a valuable mechanism through which effective selection practices can operate, potentially enhancing performance and producing significant increases in productivity and thus, frequently in profitability. However, current recognition of the potential risks associated with this enhanced performance through the impacts of risks such as inbreeding depression, offer a challenge to the effectiveness with which selection can operate. The broadening of the selection objective to address issues of risk in the selection process as described in this thesis integrates genetic objectives with economic perspectives. This is addressed through several areas. An initial consideration of this impact of accuracy in the selection process is undertaken from a single generational perspective. Longer term selection is addressed through the analysis of a range of selection and mating strategies including mate selection strategies that integrate increased genetic merit with the control of inbreeding (or similar risk factors). An assessment of long term strategies is undertaken through an adapted use of benefit cost methodology. ... The strategies were compared across a range of weightings on inbreeding (linked to decline in response). The results showed a preference for MS₀ (a mate selection option with no loss in response) over the selection and mating strategy (Pr) - however this preference was mediated when the additional cost of managing mate selection was taken into account and the weighting on inbreeding was low. Interestingly, the relative value of the MS₅ strategy was seen across all alternatives. This marked a reasonable point at which the benefits from reduced inbreeding might outweight the costs associated with some decline in potential response. While this analysis was undertaken for two levels of interest rate (0.6 and 1.0) and for two variations in the model, with one including an additional weighting on mate selection strategies to reflect the additional management costs they impose, the final results were not highly sensitive to these factors, indicating the strength of this approach for this assessment.