GENETIC CHANGES FOR PERFORMANCE TRAITS IN SLOVENIAN PIG NUCLEUS HERDS

In Slovenian pig nucleus herds, the genetic trends for performance traits in boars were investigated using mixed model methodology. Altogether, data sets from four farms with test stations consisted of 60709 records for five breeds: Swedish Landrace (SL), Large White (LW), Duroc (D), Pietrain (P), and German Landrace (GL) boars from years 1975 to 1999. Separate analyses were performed for each farm using the PEST package. Breed, season, and weight on test within breed were fixed effects, while common litter environment and additive genetic effect were treated as random. Genetic trends for days on test from 30 to 100 kg (DoT30100), feed conversion efficiency from 30 to 100 kg (FCE30100), and ultrasonically measured backfat thickness (BF100) were expressed as linear regression of the averages of predicted breeding values on the year of birth. Estimates for genetic changes varied between farms and breeds from +0.0046 to –0.374 day, +0.0019 to –0.013, and +0.262 to –0.221 mm per year for DoT30100, FCE30100, and BF100, respectively.