Variation of traits of fatteners under the impact of various factors.

The aim of this study was to determine the effect of the sire breed, sire within sire breed, genotype of fatteners, gender of fatteners, gender within sire breed, season of birth of fatteners and mass of warm carcass side on the following traits: back fat thickness - middle of the back (DSL), back fat thickness - lower back (DSK), meat yield of carcass sides (JUSKG) and percentage/share of meat in carcass sides (JUSPRO). The research was conducted in the experimental slaughterhouse and laboratory of the Institute for Animal Husbandry, Belgrade-Zemun, and included females and castrated male animals. Sires of fatteners were pure breeds: Swedish Landrace (SL, n = 10), Large White (LW, n = 3) and Pietrain (P, n = 3), while the offspring belonged to the following genotypes: pure breed - Swedish Landrace (SL, n=252), and crosses of Large White × Swedish Landrace (LW × SL) (n=170), Pietrain × Swedish Landrace (P × SL) (n=13), [Pietrain × (Large White × Swedish Landrace)] P × (LW × SL) (n=35), [Swedish Landrace × (Large White × Swedish Landrace)] SL × (LW × SL) (n=33) and [Large White × (Large White × Swedish Landrace)] LW × (LW × SL) (n=33). The study included total 536 offspring of which 276 are male castrated and 260 female animals. In the winter 24 piglets were born, in the spring 95, in the summer 148 and autumn 269 piglets. It was established that the sire within sire breed Pietrain (S:P) does not affect the variation of the studied traits of fattening pigs (P>0.05); sire within sire breed Swedish Landrace (S:SL) does not affect the varying of the trait JUSPRO (P>0.05); season of birth within the Model 1 does not affect the traits yield and share of meat (P>0.05); the offspring gender within genotype (Gender : Genotype) does not affect the variation of fat thickness at the centre of the back (P>0.05). All other factors (sire breed, sire within the sire breed - Large White, gender and genotype of fattening pigs, gender within sire breed, the mass of warm carcass side, and also birth season of fattening pigs in the Model 2) included in the models showed statistically significant impact on the variability of traits of fattening pigs (P<0.05; P<0.01 and P<0.001). [Projekat Ministarstva nauke Republike Srbije, br. TR 31081]