Phenotypic variability of fertility traits of pure breed sows in first three farrowings

Investigation of the phenotypic variability of fertility traits was performed on Swedish Landrace sows (926 sows) deriving from single herd in Serbia. Data was processed by method of least squares (Harvey, 1990), and following fixed factors were included into the model: sire, season, litter genotype and order of farrowing, as well as regression effect of age at first farrowing, duration of lactation and number of reared (raised) piglets per litter. Traits of litter size varied (P<0.01) under the influence of sire and order of parities (first two parities). Number of still born as well as reared piglets per litter depended on the litter genotype (P<0.01). Year and season had no effect on variation of litter size traits except LWW (first two and three parities). Age of sows at first farrowing demonstrated linear effect (P<0.01) on size of their litter at farrowing (first three parities). Litter size and weight at weaning were under regression effect of lactation duration as well as corrected litter size (CLS) or number of weaned piglets (NW). .