INTRABREED MATING PAIR SELECTION METHODS FOR IMPROVEMENT OF NONLINEAR MERIT FROM ADDITIVE GENETIC INHERITANCE - A REVIEW

Pair selection used for the assignment of mating pairs can be applied to dairy cattle. Intrabreed mating pair selection was reviewed for gain in additive genetic traits with nonlinear merit. Gain from pair selection was compared with that from mate selection; separate selection of sires and of dams was followed by assignment of mating pairs that used a supplementary pair selection criterion. Pair selection achieved up to 10% greater gain than from mate selection followed by random mating if the trait had a high heritability and an abrupt merit peak near the population mean. Pair selection, a modified group selection (selection of the best groups of sires and of dams relative to all other same sized groups), and special pairing among preselected sires and dams achieved gain in nonlinear merit partially with change in the progeny genetic variance and in the genetic means. Selection that changed the variance of progeny genetic traits could accelerate long-term improvement toward intermediate merit plateaus. If the multiple-trait goal in genetic means for nonlinear merits is known, then the use of linear indexes for sire and dam selection can approach a nonlinear merit goal from fewer cycles of selection than nonlinear indexes. For specific populations, greater understanding is needed of 1) when pair selection can provide greater merit gain than separate sire and dam selection and 2) how to express a comprehensive economic goal assessed from the time of AI for potential mating pairs.