Selecting for female fertility: What can be learned from the dairy experince

Genetic improvement programs in dairy cattle have until recently focused on increasing net profit by increasing gross income per cow, rather than reducing costs of production [1]. Strong selection pressure on yield traits coupled with management practices aimed at maximizing production may have resulted in undesirable side effects related to decreased fitness [2]. These concerns have been confirmed by work on reproductive efficiency done among others by Lucy [3] and VanRaden et al. [4]. There are strong motives for including reproduction in selective programs, both economical and welfare related [5].