The libido of a boar is a very important factor which determines the male’s suitability for insemination. Before a breeder is included in the semen production cycle, its libido has to be estimated, which may significantly contribute to the improvement of the organization of work in breeding stations. Many factors influence a boar’s libido. Among others, it is the male’s age and breed. In this work the influence of the breed and age on the sexual behaviour of boars is estimated, as well as the phenotype correlations between a boar’s libido and the parameters of the semen are defined. It has been proved that among the analysed breeds and hybrids the highest libido characterized PIC hybrids, and hybrids such as: Pietrain x Duroc and Duroc x Pietrain, and among the pure breed boars –Duroc breed. It has also been proved that the sexual activity of boars decreases with age. Significant correlations between a boar’s libido and some features of the semen have been shown.

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