Abstract
In genetic improvement schemes, the economic values of traits in the breeding objectives depend on time and frequency of realisation in offspring generations. A measure for this is the number of discounted expressions (NDE) derived by the gene flow procedure. These were calculated for two groups of traits or trait components: “Maternal traits” realised repeatedly during the life of the dam and “direct traits” realised once in early life of an animal. Selection was considered for purebred populations with a multi-purpose objective and for populations incorporated as specialised sire or dam breeds in a three-way crossbreeding scheme. The reproductive conditions of pigs, sheep, beef and dairy cattle were taken as example. For most realistic conditions in a purebred population, the marginal economic value for a maternal trait should be weighted with a factor between 0.55 and 0.60 of that for a direct trait. Much more relative weight should be given to maternal traits in dam breeds of a crossbreeding scheme, particularly in prolific species. Economic weights of maternal traits in a sire breed are generally negligible, but not when assuming a short investment period and inefficient use of terminal sires in the commercial level. If no reciprocal crosses of both types of F 1 dams are used, maternal traits are relatively more important in the breed used as maternal granddam of the terminal product than in that used in the grandsire position. These differences are higher for less prolific species.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.