Relative economic weights of maternal versus direct traits in breeding schemes

WOLFOVÁ, Marie a NITTER, G. Relative economic weights of maternal versus direct traits in breeding schemes. Livestock Production Science, 2004, 88, 117-127. ISSN 0301-6226.
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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 (NDEJ derived by ihe gene flow procedure. These were calculated for two groups of traits or trait components: „Maternal traits1′ 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| dams are used, maternal traits arc relatively more important in the breed used as maternal granddam of the lerminal product than in that used in the grandsire position. These differences arc higher for less prolific species. O 2003 Elsevier B.V All rights reserved

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