Effects of dietary fat saturation on fatty acid composition and gene transcription in different tissues of Iberian pigs

• Diets enriched with SFA and PUFA were assessed in fattening Iberian pigs.
• SFA diet increases MUFA and MUFA/SFA ratio in all tissues.
• PUFA diet increases PUFA and n− 6/n− 3 ratio in all tissues.
• In liver, SCD, ACACA and ME1 genes are upregulated in SFA dietary group.
• Results support the employment of dietary SFA for endogenous synthesis of MUFA.

The effect of two diets, respectively enriched with SFA (S) and PUFA (P), on FA tissue composition and gene expression was studied in fattened Iberian pigs. The FA composition of adipose, muscular and liver tissues was affected by dietary treatment. S group showed higher MUFA and MUFA/SFA ratio and lower PUFA and n− 6/n− 3 ratio than P group in all analyzed tissues. In muscle and liver the extracted lipids were separated into neutral lipids and polar lipid fractions which showed significantly different responses to the dietary treatment, especially in liver where no significant effect of diet was observed in NL fraction. The expression of six candidate genes related to lipogenesis and FA oxidation was analyzed by qPCR. In liver, stearoyl CoA desaturase (SCD), acetyl CoA carboxylase alpha (ACACA) and malic enzyme 1 (ME1) genes showed higher expression in S group. SCD, ACACA, ME1, and fatty acid synthase (FASN) gene expression levels showed a wide variation across the tested tissues, with much higher expression levels observed in adipose tissue than other tissues. Tissue FA profile and gene expression results support the deposition of dietary FA, the lipogenic effect of dietary saturated fat in liver and the employment of saturated dietary fat for endogenous synthesis of MUFA in all the analyzed tissues.