| Summary: | We aimed to determine whether the response of linoleic acid (C18:2 n-6) tissue concentration to dietary C18:2 n-6 administration, in the finishing period, is done in a different way in Iberian pig compared with a lean genotype. Therefore, 48 pigs, 24 of a lean genotype (Large White × Great York) and 24 of a fat genotype (Iberian × Duroc) were offered three commercial diets, for each genetic type, in order to provide three levels of C18:2 n-6, but maintaining constant the concentration of saturated and linolenic fatty acids (FA) in each genotype. Samples from adipose tissue (subcutaneous backfat and intramuscular fat (IMF) from Longissimus dorsi muscle) were taken. Six pigs of each genotype (two per each C18:2 n-6 level) were slaughtered at the start of the trial to estimate initial fatty acids composition. The C18:2 n-6 proportions at slaughter were higher in the subcutaneous backfat outer layer than in subcutaneous backfat inner layer for both genetic types. In both backfat layers, as the dietary C18:2 n-6 increased, the C18:2 n-6 proportions also increased in both genotypes. In IMF, the concentration of C18:2 n-6 was also altered in lean genotype according to dietary treatment, but no response was observed in Iberian pigs. Linoleic acid concentrations was higher in lean pig genotypes than in the Iberian pig, both in subcutaneous and IMF throughout the whole range of dietary linoleic acid concentration used in this experiment. These results indicate the resistance of Iberian pig to modify the proportion of linoleic in their tissues, particularly in the IMF.
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