The target of this thesis was to study the impact on the number of insemination times of sows on the farrowing percentage on Niittypirtti farm. The commissioners of the thesis are Aija and Risto Aalto and they are owners of the farm. They wanted to know if double insemination on sows can improve the farrowing percentage and renewal percentage on their farm. Regeneration percentage was 20 % and farrowing percentage was 75,7 % on the farm in year 2008. The profitability of double insemination was also studied, because the cost for insemination is part of the 85 % variable costs on the farm.

A research was carried out on the farm, in which some of the sows in oestrus were inseminated or mated once and some twice. All impregnated sows were recorded and the results were calculated based on renewal- and farrowing percentage, gilts and at least once farrowed sows in both study groups separately. Renewal- and farrowing percentages were calculated separately also for each month.

The investigation revealed that doubling the insemination would be profitable in gilts. In the group of at least once farrowed sows the difference between single and double inseminations was very small. No autumn infertility was detected on the farm. The sows with low fertility or weak oestrus should be culled. The presence of a boar is especially useful for older sows’ oestrus observation and the boar on the farm should be good in making the sows pregnant.