Selection of dam breeds under stable and declined conditions

Reproductive selection index of two dam pig breeds was established five years ago to enhance the reproductive ability of sows. Since then, positive genetic progress in the population and some economic disorders (e.g. the input and output prices disproportion) appeared in the swine sector. The study aimed to revise index according to the current circumstances and further ensure the desired gain. In three index variants, the current, optimal, and adjusted trait proportion was assessed. Economic weights (EWs) of the breeding objective traits were applied in two alternatives to evaluate the index for future stable and deteriorated conditions. Under the current index construction and stable EWs, the favourable selection gain in piglets born alive (NBA) and slight extension of farrowing interval (FI) is indicated. The optimal index construction would result in a favourable gain of both traits in one breed. The adjusted index maintained the increasing litter size equal to the current index and achieved favourable gain in FI in both breeds. The same was true for deteriorated economic conditions except for the optimised index variant, where expected higher genetic progress in one breed. Nevertheless, this genetic gain was insufficient to compensate the declined EW of traits, and the overall financial benefit was almost half of those in stable conditions. For both alternatives of evaluated economic conditions, the current index should be revised in terms of a slightly higher proportion of FI to reach favourable genetic gain in both breeding goals.