Effect of dietary fish oil supplied to pigs from weaning to 60 kg liveweight on performance, tissue fatty acid composition and palatability of pork when slaughtered at 100 kg liveweight

From weaning to approximately 60 kg liveweight, 24 castrated pigs were assi gned to one of 4 diets. The diets were barley-wheat-soyabean meal based and contained either 6% animal fat (diet 1, control), 3% animal fat + 3% fish oil (diet 2), 60% Fish oil (diet 3), or 6% of a mixture of fish oil and coc onut oil (2/1) (diet 4). The fish oil was an unrefined sand launce oil. The reafter, all pigs were switched to the finisher-diet added 2% tallow, which was fed until slaughter at approximately 100 kg liveweight. Subcutaneous f at and muscle samples of the loin were obtained by biopsy in the period 50- 60 kg liveweight and analysed for fatty acid composition. In addition, samp les of belly fat, the subcutaneous fat and the loin muscle obtained from th e carcass were evaluated in terms of fatty acid composition and iodine valu es. There was no difference between the four experimental groups with regar d to the growth performance. Fish oil supplementation increased particularl y the concentration of C22:6n-3 (DHA), C20:5n-3 (EPA), and C22:5n-3 (DPA), and addition of coconut oil increased the concentration of the Fatty acids C12:0 and C14:0 in the subcutaneous fat and muscle samples. The concentrati on of these fatty acids was lower in samples obtained from the carcass than from biopsies, but the effect of the dietary oil treatments was still sign ificant at slaughter. Thus, fish oil supplementation increased the level of DHA, EPA, and DPA in muscle and fat tissue: and decreased the n-6/n-3 rati o. However, feeding of 3-6% unrefined fish oil until approximately 60 kg li veweight caused off-flavour of the pork, which was therefore not suitable f or human consumption.