Evolution of the fatty acid profile of subcutaneous back-fat adipose tissue in growing Iberian and Landrace × Large White pigs

Abstract

The lipid content and fatty acid (FA) profile in pig tissues are strongly influenced by genotype and nutrient supply, with implications in meat quality. The de novo lipid synthesis and pattern of FA unsaturation could be an important cause of variation in the overall efficiency of energy utilization among breeds. To test the effects of pig genotype and CP supply on the evolution of back-fat tissue FA profile throughout the growing and finishing stages, 32 Iberian (IB) and Landrace 3 Large White (LR 3 LW) barrows were offered one of two diets differing in CP content (13% or 17% as fed). A pair-fed procedure (0.8 3 ad libitum intake of IB pigs) was used. Subcutaneous fat samples were taken at the dorso-lumbar region at ,38, 50, 65, 90 and 115 kg BW. Higher proportions of total monounsaturated FA (MUFA; P , 0.01) and lower proportions of total saturated FA (SFA; P , 0.01 to 0.05) were found in the outer back-fat layer of pigs both at 50 and 115 kg BW. Pig genotype affected the FA composition of both subcutaneous back-fat layers. The proportions of C18:0 and SFA in fat tissue were higher in IB than in LR 3 LW pigs from 38 to 65 kg BW, especially in the outer layer. In addition, MUFA contents were higher in IB pigs at 115 kg BW in both layers (15% on average; P , 0.01). Increased proportions of C18:2 n-6 and polyunsaturated FA (PUFA) were found in LR 3 LW pigs, irrespective of the stage of growth and back-fat layer (P<0.02). At 50 kg BW, pigs receiving the high-protein diet presented the highest C18:2 n-6, C18:3 n-3, C20:5 n-3 and PUFA contents. A significant genotype 3 CP content interaction was observed for C18:3 n-3 because of the increased concentration of this FA in LR 3 LW pigs when offered the 17% CP diet (P , 0.05). Higher C16:0 and SFA contents (15%; P 5 0.03) were found in pigs offered the 13% CP diet and slaughtered at 115 kg BW. There was a genotype 3 CP interaction for MUFA concentration because of the higher MUFA content observed in IB pigs offered the highest protein content diet (P 5 0.03). Our results suggest that genetic variation in de novo lipid synthesis and pattern of FA unsaturation might contribute to explain differences in back-fat FA profile of IB and LR 3 LW pigs under identical nutritional management. They could be also relevant to explain the low efficiency of nutrient and energy utilization in the IB pig.

Differential response of Iberian and lean pig crossbreeds to dietary linoleic acid administration

“…Moreover LW*GY pigs were six months old at slaughter while IB*D pigs were ten months old, which may possibly be one of the factors that could explain the differences in C18:2 n-6 concentration found in the present trial. However, the daily linoleic intake was in the range from 34.1 to 49.9 g for the LW*GY and from 30.5 to 58.5 g per day for the IB*D pigs, this fact means that the range of total linoleic intake in fresh matter was 1.8 times higher for IB*D than for LW*GY pigs, well above the amounts referenced in previous studies (Serra et al, 1998;Barea et al, 2013).…”

“…In a recent study, Barea et al (2013) showed that lean pigs fed a diet with 17% crude protein presented higher proportions of C18:2 n-6 and PUFA at 38 and 50 kg of body weight in the outer layer than when offered a low protein content diet (13%). In our experiment, we used the same level of crude protein in each genotype.…”

“…Serra et al (1998) and Morales et al (2003) and found that fat depots form IB pigs had higher MUFA (monounsaturated fatty acids) and lower PUFA (polyunsaturated fatty acids) proportions than those in a lean genotype (Landrace pigs), and attributed these differences to the higher lipogenesis of IB adipose tissues. Barea et al (2013) reported that genetic variation in de novo lipid synthesis and pattern of FA unsaturation might contribute to explain differences in back-fat FA prof ile of IB and Landrac × Large White pigs under nutritional management.…”

Utilization of milk fatty acids by the suckling Iberian piglets

“…At later stages of growth, our results suggest a genetic variation in the de novo lipid synthesis and pattern of FA unsaturation. Higher desaturase activity in the IB pig, in comparison with a lean pig genotype under the same nutritional regime (Barea et al, 2013) can be associated with lower efficiency of energy utilization for fat deposition found by Nieto et al (2012).…”

“…The results of a collaborative study of our research group (Barea et al, 2013) are relevant to the second question. In this study, a comparison was made on the pattern of changes of FA in subcutaneous fat of two pig genotypes which differ profoundly in growth rate and composition of growth: 32 IB and Landrace × Large White barrows were offered one of the two diets differing in CP content (13% or 17% as-fed) throughout the growing and finishing stages of growth.…”