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Different genetic models for litter size in pigs were compared. (Co)variance components at different parities were estimated by REML in two Landrace populations. Maternal genetic effects were also assessed. Data consisted of 34417 and 16750 litters records collected on each population. Different analyses for the number of pigs born in total and alive using an animal model were performed: univariate analyses with direct and maternal genetic effects (using a repeatability animal model when more than one parity was involved) and series of bivariate and multivariate analyses with each of first five parities treated as a different trait (without maternal genetic effects). The estimates of direct heritability obtained by a repeatability animal model ranged from 0.05 to 0.07. Maternal genetic effects were not significant in any populations, neither in the first parity nor in all parities. The estimates of direct heritability in each of the …