Describing backfat and Semimembranosus muscle fatty acid variability in heavy pigs: Analysis of non-genetic factors.

This study aimed to describe the multivariate structure of Semimembranosus muscle and backfat fatty acid (FA) composition in 798 Italian Large White heavy pigs and to investigate the effects of environmental factors and carcass characteristics on FA variations. The total FA variability in muscle and backfat was characterized by a negative correlation between saturated and polyunsaturated FAs, which strongly depended on the carcass adiposity. Slaughtering season was also relevant, with pigs slaughtered in autumn having more n-6 FAs and eicosadienoic acid in backfat, while pigs slaughtered in winter displayed more saturated FAs. Regarding Semimembranosus muscle, pigs with heavier belly cuts and slaughtered in autumn had higher proportions of cis-vaccenic and palmitoleic acids, while those slaughtered in summer had more saturated FAs. Slaughtering season emerged as a relevant factor shaping both backfat and muscle FA composition, indicating that more studies and attention should be paid to environmental factors, which may have effects on FA metabolism and deposition in finishing pigs.

Genetic parameters of muscle fatty acid profile in a purebred Large White heavy pig population.

Semimembranosus muscle samples from 795 Large White heavy pigs were used to determine their intramuscular fatty acid composition and to estimate the heritability and the genetic correlations of these traits. Muscle fatty acids showed heritability estimates of low-to-moderate magnitude, ranging from 0.157 for total fatty acids to 0.237 for docosahexaenoic acid. Only small differences in heritability appeared among fatty acids based on their chain length, saturation and double bond position. Omega-6 polyunsaturated fatty acids showed positive genetic correlations with carcass lean % (0.563 ± 0.005) and loin thickness (0.438 ± 0.005) while being negatively related to backfat thickness measured both by calibre (-0.225 ± 0.008) and Fat-O-Meat'er (FOM) apparatus (-0.603 ± 0.004). Interestingly, the monounsaturated fatty acid class was not correlated with carcass measures and presented only a weak positive genetic correlation with intramuscular fat (0.145 ± 0.002). This result suggests that in heavy pig breeds monounsaturated fatty acids in muscle could be selected for without interfering with carcass traits.