The use of sexual activity measurements to assess ejaculatory performance of boars

Abstract. The study involved 50 insemination boars at the age of 8–9 months at the beginning of the study. Each boar was assessed four times for its sexual activity: at the beginning of breeding service and after three, six and nine months into the insemination service. Ejaculates were collected for the purpose of the sexual activity parameters’ assessment. Physical parameters of the ejaculates were subsequently analysed. Pearson’s linear correlation was used to calculate the coefficients of a phenotypic correlation between sexual activity levels and physical parameters of the ejaculates. According to this an appropriate analysis was conducted concerning the changes in boars’ sexual activity throughout their dynamic, sexual development. It was proved, that ejaculate volume depends on the total time of copulation. The highest correlation between ejaculate volume and sexual urge levels was observed in the youngest boars at the beginning of insemination service. The correlation between the ejaculatory efficiency and a boar’s libido changes with age and sexual development. Changes in ejaculatory efficiency are the most dynamic at the age of approx. 1.5 years. At this age ejaculate volume and ejaculate sperm count dynamically increase. The insemination fitness forecasting in case of boars should include libido measurements taken at the beginning of an insemination service – within the first three months. Measurements taken at a more advanced age are of little use for the purpose of ejaculatory efficiency forecasting in case of boars.