Effect of different selection criteria and crossbreeding on sire heterosis in pigs.

Research on sire heterosis was performed in parallel on 12 boars of pure breed and 12 F1 generations of fertile and terminal breeds of pigs: F1 D×P; F1 P×D than F1 Y×L; F1 L×Y. The following traits were analyzed: age at first and second jump fertility; libido; the volume, concentration and progressive motion of spermatozoa; and semen longevity.� All hybrid boars showed superiority in libido in relation to the pure boars. Thus, the crossing and the production of synthetic boar was justified. In such situations, it is always important that their progeny, animals for fattening, were uniform in production traits at the end of fattening as part of special tests and selection of pure breed. The time of maturity and readiness of the boars did not show significant differences. It was not the sire heterosis for these traits. In this example, the semen volume was found insire heterosis, greater in the white compared to the coloured breeds. Proportional to the volume of semen and number of doses showed the same trend, with the number of spermatozoa from 3 billion in a dose was standardized for all animals tested. The progressive motion of semen was very similar and there was no statistical difference, as well as longevity.� In conclusion, sire heterosis was manifested of the hybrid boars in the following traits: libido, amount the semen and number of doses per ejaculate that directly affect on increasing intensity of selection and genetic progress. The heterosis effect was not found for other traits.