Optimal family contributions and a linear approximation (Q1909290)

In breeding programs, selection practised to change (improve) the genetic constitution of a population is measured as an increase in average breeding value, which is called genetic gain. Classical comparisons of different breeding alternatives usually focus on the gain aspect. Selection has effects on important demographic characteristics other than breeding value, including census and effective numbers. A genetic gain is combined with a decrease in effective number, which has several undesirable consequences. First, gene resources available for further selection and breeding will be reduced. Second, inbreeding will increase. Finally, the genetic diversity of production populations may become lower. In order to optimize selection methods we should consider all relevant aspects, not just genetic gain. Although there is a consensus about the need to conserve genetic diversity in breeding operations, few efforts have been made to identify methods that consider both aspects in an optimal way. \textit{D. Lindgren et al.} [Heredity 70, 619-621 (1993)]\ proposed a method for optimizing selection with respect to three factors, genetic gain, selected proportion, and effective family number, under certain assumptions. In the present study, optimal selection procedure results were calculated for a range of cases. Confounding effects between selection and genetic drift are avoided by assuming infinite family number and size. Comparisons are made with a simpler procedure, linear deployment [\textit{D. Lindgren et al.}, Theor. Appl. Gen. 77, 825-831 (1989)].