First there is the cost involved in meeting the nutritional requirement for the additional performance. The higher performance of the cross-bred animal tends to reduce the cost per unit of production, because the cost for maintenance becomes a smaller fraction of the total requirement, but there is a cost for the extra production.
A second type of cost associated with potential changes in population structure. These costs may include 1) reductions in the size (and a corresponding increase in the level of inbreeding) of an original pure-bred population which occurs because of the need to accommodate the cross-bred population, and 2) a reduced opportunity to select for female productivity in a population where some of the cross-bred females are not considered to be candidates for selection (as in any terminal-sire system)