Non-random mating for selection with restricted rates of inbreeding and overlapping generations

Abstract

-Minimum coancestry mating with a maximum of one offspring per mating pair (MC1) is compared with random mating schemes for populations with overlapping generations. Optimum contribution selection is used, whereby ∆F is restricted. For schemes with ∆F restricted to 0.25% per year, 256 animals born per year and heritability of 0.25, genetic gain increased with 18% compared with random mating. The effect of MC1 on genetic gain decreased for larger schemes and schemes with a less stringent restriction on inbreeding. Breeding schemes hardly changed when omitting the iteration on the generation interval to find an optimum distribution of parents over age-classes, which saves computer time, but inbreeding and genetic merit fluctuated more before the schemes had reached a steady-state. When bulls were progeny tested, these progeny tested bulls were selected instead of the young bulls, which led to increased generation intervals, increased selection intensity of bulls and increased genetic gain (35% compared to a scheme without progeny testing for random mating). The effect of MC1 decreased for schemes with progeny testing. MC1 mating increased genetic gain from 11-18% for overlapping and 1-4% for discrete generations, when comparing schemes with similar genetic gain and size. mating / overlapping generations / selection / rate of inbreeding / genetic response / optimum contribution

A method for the dynamic management of genetic variability in dairy cattle

“…Fourth, an implicit penalty against large full-sib families was introduced so as to favor factorial matings, since this type of matings has been generally found able to generate higher potential genetic gains in the progeny [25,28].…”

“…Improvements easy to implement such as compensatory matings have been found to be already effective [6]. The last version consists in optimizing a criterion, e.g., average coancestry between parents given their optimized contributions [25,28]. As compared to the optimization followed by random matings, this second optimization decreases inbreeding rates and increases selection responses substantially.…”

Methods for minimizing the loss of genetic diversity in conserved populations with overlapping generations

“…Simulation study has shown that both algorithms could yield very similar results . Sonesson and Meuwissen (2002) also proposed an approximated method, in which decision in a given year is made by using the parental age class contributions observed in the previous year.…”

“…According to the suggestion of Sonesson and Meuwissen (2002), a modified method was simulated, in which the weighting factors for the choice of breeding animals in a year are updated with parental age class contributions to the chosen individuals in the previous year. The result, however, showed that little extra gains could be expected from this modification.…”

Optimal genetic contribution selection in Danish Holstein depends on pedigree quality

“…Reduction of (cV Ac +2 cV APv + vVPV APv) will reduce the future rate of inbreeding and in the long run increase cumulated genetic gain (e.g. Sonesson and Meuwissen, 2002). Since the variation of merit under most circumstances is much higher than the variation of (cV Ac +2 cV APv+ vVPV APv), the absolute value of w r will often be numerically much larger than w a .…”