Development and optimization of a selection index equation for multitrait evaluation in Yorkshire pigs

Maximum genetic progress in economically important traits in pig populations depends on the efficiency of their evaluation of breeding qualities, selection strategy in breeding groups and organization of selection of parental pairs to produce offspring of high breeding value. The most effective method is the selection of individuals based on a multiple-traits production, taking into account their relationship and economic importance. This paper presents farrowing records (number of piglets born alive (NBA), average piglet weight in the litter (ABW) and fattening and meat quality data (average daily weight gain until reaching 100 kg (ADWG) and backfat thickness over 10–11 ribs (BF) in Yorkshire pigs. The economic values of reproduction traits, meat and fattening qualities of pigs were determined, and the heritability coefficients of these traits were calculated in this study. For the traits NBA, ABW, ADWG and BF in the Yorkshire pigs the heritability was 0.14, 0.20, 0.40 respectively. The results of optimization of the selection index equation for evaluation breeding value of pigs by traits depending on the use of animals in different breeding systems (purebred, crossbreeding) are presented. Based on the developed selection indexes, the formation of breeding groups was analyzed. Using the rank correlation coefficient, the level of relation between the same animals, which were estimated by single trait and different variants of selection index, was determined (the range of variation ranged from -0.21 to +0.65 on total index and from +0.11 to +0.84 on optimized selection index).