The Assessment of Breeding Value of First Farrowed Sows by the Method of Selection Indices

Abstract

The goal of this research paper was to assess the breeding value of first farrowed Swedish Landrace sows by the means of selection indices method. The traits on the basis of which the breeding value of animals was assessed are following: daily liveweight gain, average thickness of collected back fat measured at five sites and number of liveborn piglets in the first litter. The liveweight gain and carcass quality traits determined at the end of performance test were corrected for the body mass of 100kg by the method of basic indexes and following mean values were determined: for corrected daily liveweight gain (KZDP) 499.92g/day and for corrected average collected backfat thickness (KSL) 20.01mm. The first farrowed sows on average produced 8.09 liveborn piglets in the litter. Studying the effect of the gilts` birth year and season on KZDP and KSL it was determined that the gilts` birth year and season had no statistically significant influence (P>0.05) on KZDP variation but they had a statistically significant effect on KSL (P lt 0.01). The year and the season of farrowing and the class of backfat thickness in performance test did not display any statistically significant effect (P>0.05) on BZPL, while the KZDP class and the age at first farrowing had a statistically significant effect on the variability of these trait (P lt 0.05; P lt 0.01). All studied traits varied statistically significantly (P lt 0.01) under the impact of the gilts` sire or dam. Heritability coefficients were: h2= 0.402 for KZDP, h2= 0.261 for KSL and h2= 0.177 for BZPL. The relation between KZDP and KSL was of a medium strength both at phenotype and genetic levels (rph=0.491; rg=0.411), while the relation of these traits with BZPL did not exist, except for the genetic relationship between KSL and KZDP which was of a medium strength (rg=0.252). Three equations for the selection indexes were constructed among which as the most optimal was chosen the one which includes all three traits (KZDP, KSL and BZPL) and whose correlation coefficent of selection index and aggregate genotype was rIAG = 0.5473.