The fatty acid composition in feedstuff is studied especially for their influence on carcass value and meat quality. But the interest in their impact on reproduction efficiency of animals has been rising in recent years. The addition of fat in feed dose for pregnant and lactating sows can increase the store of energy and fatty acids in piglets and improve their vitality after the birth. The content of fat in sow colostrum and milk is also influenced by dietary fatty acids. The deficiency of EPA and DHA in sows decreases number of born piglets, causes higher litter variability, lower growth ability of piglets and increases piglet losses from birth to weaning.