Dietary energy source largely affects tissue fatty acid composition but has minor influence on gene transcription in Iberian pigs1

Abstract

A trial was performed to compare the effects of different dietary sources of MUFA on the fatty acid (FA) composition, lipid metabolism, and gene transcription in different tissues of Iberian pigs. Twenty-seven Iberian male pigs of 28 kg live weight (LW) were divided in 2 groups and fed with 1 of 2 isocaloric diets: a standard diet with carbohydrates as energy source (CH) and a diet enriched with high-oleic sunflower oil (HO). Ham adipose tissue was sampled by biopsy at 44 and 70 kg LW. At 110 kg LW pigs were slaughtered and backfat, loin, and liver tissues were sampled. Animals of the HO group showed higher MUFA content and lower SFA in all the analyzed tissues (P < 0.001). These main effects were established early during the treatment and increased only slightly along time. Small diet effects were also detected on PUFA, which showed differences according to sampling time, tissue, and lipid fraction. Effects of diet on gene expression were explored with a combined approach analyzing adipose tissue transcriptome and quantifying the expression of a panel of key genes implicated in lipogenesis and lipid metabolism processes in backfat, muscle, and liver. Backfat transcriptome showed small effects of diet on gene expression, in number and magnitude. According to the posterior probabilities (PP) of the probe-specific expression differences between dietary groups (PP < 0.01), 37 genes were considered differentially expressed (DE). Gene ontology allowed relating them with several biological functions including lipid metabolic processes. Quantitative PCR confirmed several DE genes in adipose tissue (RXRG, LEP, and ME1; P < 0.0001, P < 0.05, and P < 0.0001, respectively), but no DE gene was found in loin or liver tissues. Joint results agree with a metabolic adjustment of adipose tissue FA levels by the subtle effect of the diet on the regulation of several lipid metabolism pathways, mainly FA oxidation and prostanoid synthesis, with LEP, RXRG, and PTGS2 genes playing mayor roles.

Influence of outdoor rearing and oleic acid supplementation on lipid characteristics of muscle and adipose tissues from obese Alentejano pigs

“…The fact that muscle composition was less affected by this treatment than the other tissues (see below) could reflect an effect at the transcriptional or enzymatic activity levels, as previously observed by Óvilo et al. ().…”

“…(), Ventanas et al. () and (Óvilo et al., ), neutral SFA as well as MUFA and PUFA in DSFo layer were more sensitive to dietary modifications than intramuscular neutral FA proportions, suggesting different patterns in dietary FA deposition between these tissues. In fact, IMF is the last fat depot to develop, and it may respond to dietary manipulations in a different manner when compared to other adipose tissue depots (Dannenberger et al., ; Doran et al., ).…”

“…In fact, during the last 10 days of trial, OUT pigs were submitted to a ~24% reduction in average maximum and minimum temperatures, while IND pigs thrived in similar temperatures (see Martins et al., ). The effects of MUFA‐enriched diets on gene transcription are less known than those of SFA and PUFA, and have not been investigated in Iberian (Óvilo et al., ) and Alentejano pigs. When compared to LO‐fed pigs, HO‐fed ones presented a reduced expression of ACACA and a down‐regulated FASN gene ( − 10 and − 65% respectively).…”

“…Meanwhile, SCD expression was not affected by the lipid content of diets. The expression and activity of this gene in mammals is known to be repressed in several tissues by dietary PUFA (Benítez et al., ; Dannenberger, Nuernberg, Nuernberg, & Priepke, ; Doran et al., ; Ntambi, ) and to a lesser (Jeffcoat & James, ; Landschulz, Jump, Macdougald, & Lane, ) or no extent (Óvilo et al., ) by oleic acid, as well as induced by SFA (Hu, Qing, & Chen, ; Ntambi, ). Therefore, the content of these dietary FA and their variations among experimental diets (with a three‐fold higher, three‐fold lower and ~two‐fold higher content in LO diet respectively) may have had opposite effects, contributing to a lack of significant diet effect.…”

Nutrigenomics in Farm Animals

“…In this breed, interactions genome-nutrition are expected to have a main role on phenotype, and different diets regarding energy source and FA profile have been essayed in order to study their effects on composition and lipid metabolism in adipose, muscular and hepatic tissues. For this purpose, isoenergetic and isoproteic diets of different lipid composition were compared, supplemented with 6% high oleic sunflower oil or carbohydrates as source of energy [11,12]. At the level of tissue composition, the results showed both the direct deposition of nutrients and also their influence on endogenous synthesis, with a higher proportion of saturated fat in carbohydrate-based fed animals, as a consequence of increase de novo lipogenesis in this group, while animals fed with high oleic diet show more monounsaturated fat in their tissues.…”