1 Departamento de Fisiología y Bioquímica de la Nutrición Animal, Instituto de Nutrición Animal (INAN), Estación Experimental del Zaidín (CSIC), Cno. del Jueves s/n, 18100 Armilla, Granada, Spain.
Animal. 2013 Apr;7(4):688-98. doi: 10.1017/S175173111200184X. Epub 2012 Oct 2.
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 × Large White (LR × LW) barrows were offered one of two diets differing in CP content (13% or 17% as fed). A pair-fed procedure (0.8 × 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 × 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 (+5% on average; P < 0.01). Increased proportions of C18:2 n-6 and polyunsaturated FA (PUFA) were found in LR × 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 × CP content interaction was observed for C18:3 n-3 because of the increased concentration of this FA in LR × LW pigs when offered the 17% CP diet (P < 0.05). Higher C16:0 and SFA contents (+5%; P = 0.03) were found in pigs offered the 13% CP diet and slaughtered at 115 kg BW. There was a genotype × CP interaction for MUFA concentration because of the higher MUFA content observed in IB pigs offered the highest protein content diet (P = 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 × 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.
猪组织中的脂质含量和脂肪酸（FA）组成受基因型和营养供应的强烈影响，这对肉质有影响。从头合成的脂质和 FA 不饱和模式可能是不同品种之间整体能量利用效率差异的一个重要原因。为了测试猪基因型和 CP 供应对生长和育肥阶段背脂 FA 组成演变的影响，32 头伊比利亚（IB）和长白×大白（LR × LW）阉公猪被提供两种不同 CP 含量的饮食之一（作为饲料的 13%或 17%）。采用限饲程序（IB 猪的 0.8×自由采食量）。在大约 38、50、65、90 和 115 kg BW 时，在背腰区取皮下脂肪样品。在外层背脂中，50 和 115 kg BW 时，猪的总单不饱和脂肪酸（MUFA；P < 0.01）比例更高，总饱和脂肪酸（SFA；P < 0.01 至 0.05）比例更低。猪基因型影响两种皮下背脂层的 FA 组成。38 至 65 kg BW 时，IB 猪的 C18:0 和 SFA 在脂肪组织中的比例高于 LR × LW 猪，尤其是在外层。此外，IB 猪在 115 kg BW 时 MUFA 含量更高（平均增加 5%；P < 0.01）。LR × LW 猪无论生长阶段和背脂层如何，C18:2 n-6 和多不饱和脂肪酸（PUFA）的比例都增加（P ⩽0.02）。在 50 kg BW 时，饲喂高蛋白饮食的猪 C18:2 n-6、C18:3 n-3、C20:5 n-3 和 PUFA 含量最高。由于在提供 17% CP 饮食时 LR × LW 猪的这种 FA 浓度增加，因此观察到 C18:3 n-3 的基因型×CP 含量存在显著的互作（P < 0.05）。饲喂 13% CP 饮食并在 115 kg BW 时屠宰的猪 C16:0 和 SFA 含量更高（增加 5%；P = 0.03）。由于饲喂最高蛋白质含量饮食的 IB 猪 MUFA 含量较高，因此 MUFA 浓度存在基因型×CP 互作（P = 0.03）。我们的结果表明，从头合成脂质和 FA 不饱和模式的遗传变异可能有助于解释在相同营养管理下 IB 和 LR × LW 猪背脂 FA 组成的差异。它们也可能与 IB 猪营养和能量利用效率低有关。
