Fatty acids (FA) play a major role in relation to mucosal immune responses, epithelial barrier functions, oxidative stress, and inflammatory reactions. The dietary FA composition and the molecular structures (chain length and number of double bonds) influence digestion, absorption and metabolism, and the bioactivity of the FA. Piglets post-weaning having an immature intestine and not fully formed immune functions are very vulnerable to invading microorganisms. Manipulation of the milk FA composition via sow nutrition, or inclusion of dietary fat sources in the feed for newly weaned pigs, may be used as a strategic tool to enhance pig performance and their gut health and function pre- and post-weaning. Medium-chain fatty acids (MCFA) are absorbed directly into the portal blood and may contribute to immediate energy for the enterocytes. In addition, the MCFA, similarly to the short-chain fatty acids (SCFA), possess antibacterial effects and may thereby prevent overgrowth of pathogenic bacteria in the gastrointestinal tract. The essential FA, linoleic (LA) and α-linolenic (ALA) FA, form the building blocks for the long-chain polyunsaturated n-3 and n-6 FA. The conversion of ALA and LA into n-3 and n-6 eicosanoids, respectively, influences the molecular structures of metabolites and inflammatory reactions and other immune responses upon bacterial challenges. Dietary manipulation of the lactating sow influences the transfer of the n-3 and n-6 polyunsaturated fatty acids (PUFA) from the sow milk to the piglet and the incorporation of the FA into piglet enteric tissues and cell membranes, which exerts bioactivity of importance for immune responses and the epithelial barrier function. Especially, the n-3 PUFA present in fish oil seem to influence the gut health and function of pigs, and this is of importance during the transition periods such as post-weaning in which piglets are prone to inflammation. The proportion of unsaturated FA in the cell membranes influences the susceptibility to oxidative stress. Oxidative stress accompanies infectious diseases, and the development of lipid peroxides and other reactive oxygen products may be harmful to the epithelial barrier function. Fatty acid peroxides from the feed may also be absorbed with other lipid-solubles and thereby harm the intestinal function. Hence, antioxidative protection is important for the enteric cells. In conclusion, manipulation of the dietary FA composition can influence the gut health and function in pigs and may support a normal immune system and modulate resistance to infectious diseases during especially stressful phases of a pig's life such as post-weaning.

中文翻译：

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日粮脂肪酸对断奶前后猪肠道健康和功能的影响。

脂肪酸 (FA) 在粘膜免疫反应、上皮屏障功能、氧化应激和炎症反应中发挥着重要作用。膳食FA组成和分子结构（链长和双键数量）影响消化、吸收和代谢以及FA的生物活性。断奶后的仔猪肠道尚未成熟，免疫功能尚未完全形成，非常容易受到微生物的入侵。通过母猪营养来控制牛奶 FA 组成，或在新断奶猪的饲料中添加日粮脂肪来源，可作为增强猪生产性能及其断奶前后肠道健康和功能的战略工具。中链脂肪酸 (MCFA) 直接吸收到门静脉血中，可能为肠上皮细胞提供即时能量。此外，与短链脂肪酸（SCFA）类似，中链脂肪酸也具有抗菌作用，从而可以防止胃肠道中病原菌的过度生长。必需的 FA，亚油酸 (LA) 和 α-亚麻酸 (ALA) FA，构成长链多不饱和 n-3 和 n-6 FA 的构建模块。ALA 和 LA 分别转化为 n-3 和 n-6 类二十烷酸，影响代谢物的分子结构以及细菌攻击时的炎症反应和其他免疫反应。泌乳母猪的日粮控制会影响母猪奶中 n-3 和 n-6 多不饱和脂肪酸 (PUFA) 向仔猪的转移，以及 FA 融入仔猪肠组织和细胞膜中，从而发挥重要的生物活性用于免疫反应和上皮屏障功能。特别是，鱼油中存在的 n-3 PUFA 似乎会影响猪的肠道健康和功能，这在仔猪易发炎症的断奶后等过渡期非常重要。细胞膜中不饱和脂肪酸的比例影响氧化应激的敏感性。氧化应激伴随感染性疾病，脂质过氧化物和其他活性氧产物的产生可能损害上皮屏障功能。饲料中的脂肪酸过氧化物也可能与其他脂溶物一起吸收，从而损害肠道功能。因此，抗氧化保护对于肠细胞很重要。总之，控制日粮 FA 成分可以影响猪的肠道健康和功能，并且可以支持正常的免疫系统，并在猪生命中特别紧张的阶段（例如断奶后）调节对传染病的抵抗力。