Managing genetic diversity in pig populations: implications of optimal contribution selection in the Black Slavonian pig

Abstract

Implications of optimal contribution selection for litter size in the Black Slavonian pig were analysed using 23,882 litter records from 6764 sows. To obtain population parameters, pedigree analysis was performed for 7367 animals. The average inbreeding coefficient was 2.87%, the average inbreeding rate was 1.96%, and the effective population size was 25.52. The average maximum number of generations traced back was 4.12 and the average number of full generations was 1.17. Selection candidates were chosen using the following criteria: animals had no culling date in the record; animals had sufficient pedigree depth and an estimated breeding value. Using these criteria, 8 boars among 24 and 386 sows among 2028 were defined as selection candidates. Two scenarios were tested. The first scenario was based on the application of the traditional optimal contribution selection with the maximisation of genetic gain and restricting the mean kinship in the offspring accounting also for breeding values. The second scenario was based on minimising inbreeding by restricting the average kinship of the population. In the first scenario, different kinship constraints between candidates resulted in changing the number of selected animals and changed the average breeding values such that the number of selected candidates increased when the kinship constraint was stronger, with a simultaneous decrease in breeding values. The second scenario resulted in increased inbreeding when the additional weight on genetic gain was added. The results of the study showed that the use of optimal contribution selection in Black Slavonian is possible, however, with additional efforts to improve pedigree and data quality. HIGHLIGHTS Genetic diversity analysis and application of optimal contribution selection in the Black Slavonian pig were analysed using pedigree. Results indicate a recent loss of genetic variability in the Black Slavonian pig. Optimal contribution selection enabled simultaneous genetic improvement and achieving conservation goals.