日粮脂肪酸对仔猪断奶前后肠道健康和功能的影响
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时间:2020-04-29
脂肪酸在粘膜免疫反应、肠道上皮屏障功能、氧化应激和炎症反应发挥着重要作用。日粮脂肪酸组成和分子结构(脂肪酸链长度和双键数量)影响着脂肪酸消化吸收、代谢,及其生物活性。仔猪断奶后肠道发育不完善,尚未完全形成的免疫功能非常容易受到微生物的侵袭。通过母猪日粮调节乳脂肪酸组成,或者断奶仔猪日粮脂肪来源,可以改善断奶仔猪生长性能、肠道健康和功能。
中链脂肪酸可以直接吸收进入血液,并能给肠上皮细胞提供能量。此外,中链脂肪酸同短链脂肪酸一样具有抑菌效果,可能阻止肠道病原菌的过度生长。必需脂肪酸(亚油酸和α-亚麻酸)是合成长链多不饱和脂肪酸(n-3,n-6)的基础。亚油酸和α-亚麻酸到长链多不饱和脂肪酸(n-3,n-6)的转变影响着代谢物的分子结构和细菌感染后的炎症反应、其它免疫反应。通过调整哺乳母猪日粮管理影响n-3,n-6多不饱和脂肪酸从母乳向仔猪的转移,仔猪肠道组织和细胞膜对n-3,n-6多不饱和脂肪酸的吸收,在这些组织中脂肪酸对免疫反应和上皮屏障功能发挥着重要的生理活性。鱼油中的n-3多不饱和脂肪酸可以影响猪肠道健康和功能,这对仔猪断奶后容易发炎的过渡阶段具有重要意义。细胞膜上不饱和脂肪酸的比例影响其对氧化应激的耐受程度。伴随着感染性疾病的氧化应激、脂质过氧化物的形成和其它活性氧产物可能会损伤肠道屏障功能。来源于饲料的脂肪酸过氧化物可能与其它脂溶性物质一起被吸收,从而损害肠道功能。因此对于肠道细胞来说抗氧化保护非常重要。
总之,调节日粮脂肪酸组成会影响猪肠道健康和功能,并在生产中的应激阶段(如断奶)维持正常的免疫系统、调节机体对传染性疾病的抵抗力。
Effects of dietary fatty acids on gut health and function of pigs pre- and post-weaning
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.
文章来源:猪营养国际论坛
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