The aim of the study was to determine the influence of the year's season (spring, sum-mer, autumn, winter) on farrowing rate of sows of Polish Large White, and number of piglets born litter, resulting from different methods of natural mating and insemination. After detection of the estrus in sows, the following procedures were carried out in the following months of the year: 1. double natural mating (189 of sows), 2. combined, first - natural mating, second - ar-tificial insemination after 12 hours (141 of sows), 3. double artificial insemination with the 12 hours interval (504 of sows). The sows were mated with boars of Polish Landrace breed, the insemination was carried out with the use of semen of boars of that breed. The results revealed that the farrowing rate of sows was the lowest in May, regardless of method of natural mating or insemination used, and the highest number of piglets was characteristic for litters born in summer and autumn. The method of natural mating or insemination did not influence the number of piglets in litters. Another important observation is that the farrowing rate did not decrease in summer, especially after insemination.

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