The aim of this study is to evaluate the quality of ejaculates of purebred boars born in different seasons of the year. The material for the studies consisted of 49,734 ejaculates sam- pled from 363 boars of 6 breeds (Polish Landrace (PL), Polish Large White (PLW), Duroc, Hampshire, Pietrain Line 990) used in the years 1994–2006 in the Małopolskie Centre of Biotechnology, the Boars Exploitation Station in Czermin. The ejaculates were evaluated on the basis of: volume, percentage of progressively motile spermatozoa, the concentration of spermatozoa, percentage of spermatozoa with major, percentage of spermatozoa with minor, total number of progressively motile spermatozoa, number of insemination doses obtained from a single ejaculate. It was concluded in the studies that the quality of the ejaculate of boars of the breeds evaluated was diverse in all birth seasons. The results indicate that the birth season of a boar may be an effective factor of organising the breeding use. A high reproductive potential expressed by the number of insemination doses is presented by the Polish Landrace breed boars born in autumn and winter, the Polish Large White boars from spring and summer births, the Duroc boars born in summer, the Hampshire boars born in spring and autumn, Line 990 boars born in winter, and the Pietrain boars from every birth season.

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