Published online by Cambridge University Press: 02 September 2010
Theoretical rates of genetic response are calculated for adult multiple ovulation and embryo transfer (MOET) nucleus breeding schemes and conventional breeding systems in dairy cattle. For a single trait breeding objective, the relative responses with MOET schemes decline as the heritability falls and the number of progeny in the progeny test scheme increases. Selection for an aggregate breeding objective of milk yield and another trait, for different values of heritability, correlation and relative economic importance, is also examined. Generally, the overall response of efficient MOET schemes exceeds the progress of an efficient conventional breeding scheme with 50 to 100 daughters per bull. Only if the relative economic weight for the lowly heritable trait exceeds 0·60 and the progeny test is on 200 offspring are conventional systems superior. Testing additional paternal half-sib groups from a MOET scheme gives a considerable extra response, especially when lowly heritable traits have a dominating economic importance.