The cost of heterosis
Heterosis has sometimes been referred to as a free opportunity for increased profitability. Although it may be worth more than it costs, heterosis is not free. Lt involves two types of costs.
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)