Effect of feeding level and linseed oil on some metabolic and hormonal parameters and on fatty acid profile of meat and fat in growing pigs

In an experiment with 56 pigs, the effects of feeding level and linseed oil supplement on fattening and slaughter parameters, the weight of internal organs, the concentration of hormones and indicators of protein and lipid metabolism, and the fatty acid profile of m. semimembranosus and backfat were investigated. During the growing period, all animals received a feed supplemented with 4% linseed oil. At the end of the growing period (23-61 kg body weight), compared to semi-ad libitum fed animals, animals that were fed restrictively (25% less feed) during this period were characterized by lower daily gains (P <= 0.001), greater meatiness (P <= 0.01), lower weight of internal organs, higher level of growth hormone (P <= 0.05), lower levels of thyroid-stimulating hormone and blood urea nitrogen (P <= 0.05), and dietetically more beneficial profile of fatty acids (more polyunsaturated fatty acids [PUFA]). During realimentation (61-104 kg body weight), when all animals were fed semi-ad libitum diets with 0 or 4% linseed oil, daily feed intake and daily weight gains of the pigs that had previously been restrictively fed, were greater than in animals fed semi-ad libitum throughout fattening. Compensatory growth was found for the internal organs. Animals that received linseed oil diets throughout fattening were characterized during the finishing period by a higher rate of growth (P: 0.001), higher concentrations of triiodothyronine (T-3) and insulin (P <= 0.05), and a greater proportion of n-3 PUFA in the fatty acid profile of m. semimembranosus and backfat (P <= 0.001).