Fixed effects in models for the genetic evaluation of backfat thickness and time on test in gilts

Fixed effects in the model for backfat thickness and the time on test were evaluated. Data records from large scale farm in period from January 1998 to December 2007 were analyzed. Two models were developed. Fixed effects of genotype, season and weight were included in the model for backfat thickness. The model for time on test was simpler than model for backfat thickness, containing only fixed effects of genotype and season. Choice of the model was based on coefficient of regression and degrees of freedom. The model for backfat thickness explained 56% of the variability, while the model for time on test explained 65% of variability. The results of this investigation will be useful in future development of the model for prediction of breeding values for gilts in field test.