EN
Pigs of Pietrain (P) and Polish Synthetic line of 990 (S) were slaughtered at 25, 70, 90, 110 and 130 kg BW and the chemical composition of musculus longissimus dorsi and its fatty acid profiles were determined. The Pietrain pigs were characterised by lower (P<0.01) concentration of intramuscular fat, total SFA (P<0.05) and MUFA (P<0.01) than pigs of the synthetic line 990 at each BW (P<0.05).Simultaneously the Pietrain breed were characterised by higher (P<0.01) concentration of all acids belonging to PUFA group. Concentration of total SFA increased (P<0.01) along with increased body mass of pigs. MUFA was similar at each investigated BW. However, in the case of Pietrain breed increasing concentration of the PUFA was observed till animals reached approximately 110 kg BW, while in Synthetic line only till 70 kg BW. Similar course was observed in the change of C18:2n-6 concentration. However, the concentration of C18:3n-3 decreased (P<0.05) along with the growth of the animals. The course of changes in concentration of C20:3n-6 and C20:4n-6 generally agreed with the course detected for total amount of PUFA. Activity of the Δ5 desaturase was higher (P<0.01) in the pigs of the synthetic line. The activity of the investigated enzymes did not differ between breeds. Activities of the elongase and Δ5 desaturase decreased during the growth of the pigs. Estimated values of the Pearsons’ correlation between body mass/age of the pigs and activity of investigated enzymes showed the opposite relationship between them. However, they were stronger and statistically more significant for the synthetic line of pigs.