Quantification of active population size effect on genetic progress in MOET breeding programmes applying bulls selection on collaterals

The results of simulation demonstrate that really, the active population size constitutes an important factor for the genetic efficiency in the breeding programs based on the MOET and bull selection on collaterals. Optimum size in the active population-that confer an acceptable efficacy (Delta G=2.5289%-2.5522%) is about 50000-60000 cows. The annual genetic progress recorded an ascendant evolution in the same time by increasing the population size, from Delta G=2.3037% (10000 cows) to Delta G=2.6638% (150000 cows). Increasing the genetic progress wasn't linear, the selection effect having the tendency to limit over about 50000-60000 cows. The results suggest it isn't justified to use very large active population in the activity of genetics breeding in dairy cattle, the gain in the genetic progress couldn't compensate for the supplementary costs for its producing.