Postweaning Genetic Parameters and Indexes for Swine

Data were analyzed on 5,952 pigs tested at the Ohio Swine Evaluation Station to estimate genetic parameters and compare testing strategies for selection for postweaning net merit. Net merit was defined as feed consumed from 20 to 90 kg, days to 90 kg and percentage lean cuts at 90 kilograms. Genetic parameters agreed well with those previously published. Theoretical examination of several indexes suggested that most breeders should test their pigs in groups on-the-farm and use an index combining growth and leanness. Approximately 10% improvement in changing net merit should result from measuring feed consumption. This could be worthwhile in testing stations and elite herds. Testing two littermate boars in a pen had a 6% advantage in predicting net merit compared to testing a single boar. Use of central test facilities for testing sibs to obtain slaughter data would not be recommended.