Introduction:
The supplementation of preterm infant formulas with n-3 fatty acids is now well accepted, while the benefits of adding n-3 fatty acids to formula milk for term infants remains controversial.

Objective:
To investigate the effect of fish oil supplementation of maternal diet during pregnancy and lactation, and the effect of fish oil addition to formula milk on gene expression and fatty acids composition in the small intestine, liver, and quadriceps femoris muscle of offspring in the first month of life.

Material and Methods:
Four groups of piglets were used: PC – piglets fed milk from control sows from birth for 28 days, PS – piglets fed milk from sows supplemented with 10 mL/d menhaden oil from birth for 28 days, PF – piglets fed formula from control sows from day 7 after birth for 28 days, and PFS – piglets fed formula with 1 mL/d menhaden oil from control sows from day 7 after birth for 28 days. On day 28, all piglets were slaughtered and samples of plasma, small intestine, liver and muscle were collected.

Results:
The results provided evidence that maternal dietary supplementation with fish oil significantly increased the expression of PPARα and FABP genes involved in fatty acids transport and metabolism, in comparison to the levels observed in offspring fed the supplemented formula milk.

Conclusions:
The differences in genes’ expression, as well as n-3 LP-PUFA concentration in plasma and tissue between PS and PFS groups of piglets were insignificant. We suggest that fish oil supplementation of formula milk for term infants constitutes a sufficient way to increase piglets’ plasma and tissue concentrations of n-3 fatty acids, producing a similar effect to maternal diet supplementation with these fatty acids.