Effect of dietary linseed oil and α-tocopherol on selected properties of pig fat

Abstract

The effect of linseed oil and α-tocopheryl acetate on the fatty acid composition, the susceptibility to oxidation of pig adipose tissue and the subcutaneous fat consistency was studied. Fifty female pigs were penned individually at approximately 25 kg and fed a conventional diet until 48.1 ± 3.5 kg. Pigs were then randomly assigned to one of five diets including: C, control (3% sunflower oil); L and LE (3% linseed oil) and LO and LOE (1.5% of linseed oil plus 1.5% of olive oil). LE and LOE had 200 mg α-tocopheryl acetate added per kilogram of diet whereas C, L and LO had 20 mg α-tocopheryl acetate added per kilogram of diet. Animals were slaughtered at 100.1 ± 7.1 kg. In the lard of the control diet animals the concentration of n-6 fatty acids rose markedly during the first 4 wk, and then stabilised. The concentrations of these fatty acids in the lard of L and LE group were not modified over time. In the lard of animals fed on LO and LOE diets, a moderate linear rise in the concentration of n-6 fatty acids was found. The addition of linseed oil to pig diets either as the only source of dietary fat or in combination with olive oil produced a higher (P < 0.0001) C18:3n–3 and total n-3 fatty acids concentration in adipose tissue lipids. The n6/n3 ratio was sharply reduced (from 9.88 in the control batch to at least 2.48) when pigs were fed diets enriched in linseed oil. It was concluded that the higher the dietary concentration of n-3 fatty acids the greater and faster the response of pig tissue. The α-tocopherol content of adipose tissue from pigs fed diets enriched with α-tocopheryl acetate (200 mg kg-1 feed) was significantly greater (P < 0.001) that those from pigs receiving a basal diet of 20 mg kg-1 feed. Adipose tissue from pigs fed diets enriched in C18:3n-3 showed higher susceptibility to oxidation than that from pigs fed diets containing high levels of C18:2n-6, but dietary supplementation with α-tocopheryl acetate markedly reduced the pig fat oxidation in groups fed diets enriched in n-3 fatty acids, eliminating the difference in the oxidative status between the two treatment groups. No effect of dietary treatment on lard rheological parameters (hardness, adhesiveness, springginess, gumminess and chewiness) of fat was observed. Conclusively, the diet enrichment in both linseed and α-tocopherol is a very effective approach to produce a healthier fat and to prevent the lipid oxidative deterioration. Key words: Pig, adipose tissue, linseed oil, fatty acid, α-tocopherol