Effect of n − 3 polyunsaturated fatty acid intake on its deposition in the body of growing-finishing pigs

• Fatty acids composition in the pig body is related to their composition in the diet.
• The increase of n − 3 PUFA intake increased their deposition in the pig body.
• The deposition of n − 3 PUFA in the body depended on the source of fat in the diet.
• The increase of n − 3 PUFA intake reduced its net deposition efficiency by pigs.
• Diet with linseed and fish oils the best improved body fatty acids composition.

The aim of the current study was to provide information about the relationship between n − 3 polyunsaturated fatty acid (PUFA) intake and their deposition in the body parts (meat, subcutaneous fat, viscera, and inedible parts) and whole body of growing-finishing pigs. Thirty crossbred pigs – ♂ Duroc × ♀ (Polish Large White × Danish Landrace) were divided into 4 groups (A–D) and grown to 60–105 kg body weight (BW) by feeding isoenergetic (average 13.5 ME MJ/kg) and isolysinic (average 7.4 g/kg standardised ileal digestible lysine) diets, where 10% metabolisable energy was replaced by fat mixtures totalling 3.5% per kg of the diet. Diet A contained 2% fish, 1% rapeseed oils, and 0.5% lard; diet B contained 2.5% rapeseed and 1% linseed oils; diet C contained 2.3% linseed, 1% rapeseed oils, and 0.2% lard; and diet D contained 2.5% linseed and 1% fish oils. The diets had similar linoleic acid (C18:2 n − 6, LA) amounts, but different amounts of linolenic (C18:3 n − 3, ALA, 2.07–8.75 g/kg), eicosapentaenoic (C20:5 n − 3, EPA, 0–0.689 g/kg), docosapentaenoic (C22:5 n − 3, DPA, 0–0.117 g/kg), and docosahexaenoic (C22:6 n − 3, DHA, 0.046–0.907 g/kg) acids. Dietary n − 6/n − 3 ratio was reduced to 4.78–1.76 (diet A–diet D, respectively) by changing the n − 3 PUFA content. The average total deposition of ALA was approximately two-fold greater in pigs fed diets with high rapeseed-oil contents (diet B; P < 0.01) and three-fold greater with diets rich in linseed oil (diets C and D; P < 0.01), than animals fed fish-oil diets (diet A). The average total deposition of EPA + DHA was approximately two-fold greater when pigs were fed fish-oil diets (diets A and D) compared with high linseed- (diet C) and rapeseed-(diet B) oil diets (P < 0.01). Higher deposition of ALA in whole body tissue was found in subcutaneous fat compared with meat (average 224 vs. 80 g; P < 0.01), while higher EPA + DHA deposition was in the meat compared with subcutaneous fat (average 28 vs. 19 g; P < 0.01). The net deposition efficiency (DE) of ALA in the whole pig body ranged from 50.4% (diet D) to 69.0% (group A; P < 0.001), while the net DE of EPA + DHA was approximately 48.7% (groups A and D), or they were partially synthesised de novo (group B and C) from their precursor.