Decuypere J A, Dierick N A
Department of Animal Production, Faculty of Agricultural and Applied Biological Sciences, Ghent University, Proefhoevestraat 10, B-9090 MELLE, Belgium.
Nutr Res Rev. 2003 Dec;16(2):193-210. doi: 10.1079/NRR200369.
In the search for alternatives to banned in-feed antibiotics, a concept was developed based on studies with medium-chain fatty acid-containing triacylglycerols (MCTAG) and selected lipases for in situ generation of diacylglycerols, monoacylglycerols and medium-chain fatty acids (MCFA) in the stomach and proximal gut of piglets. MCFA are known to have strong antibacterial properties but can hardly be used as such because of their repellent odour and taste. Those problems could be overcome by the generation of MCFA in situ. The concept was tested in vitro and validated in vivo with gastric-cannulated piglets and under field conditions, including effects on zootechnical performance, with classical antibacterial growth promoters or organic acids acting as positive controls. Furthermore, the metabolic and dietary constraints on the nutritional and nutritive use of MCTAG and/or MCFA (for example, the effects on digestive physiology, gut flora, feed intake, performance, carcass composition) are reviewed. The role of natural preduodenal lipase activity, the presence of endogenous plant lipase activity in raw materials and the feasibility for exogenous lipase addition to the feed are discussed, in order to optimize the concept. The present review illustrates the similarity of the action of MCFA and commonly used antimicrobials on the flora (total flora, Gram-positive flora, Gram-negative flora, potential pathogens) and epithelial morphology and histology in the foregut. These observations are believed to be the basis for obtaining optimal growth performances. In addition, these naturally occurring antimicrobial agents have little or no human or animal toxicity and induce no problems of residues and cross-resistance induction. They are proposed as a valuable alternative to in-feed antibiotics, used for growth promotion, and even for the preventive and curative treatment of gastrointestinal diseases.
在寻找禁用的饲料抗生素替代品的过程中，基于对含中链脂肪酸甘油三酯（MCTAG）的研究以及选择的脂肪酶，提出了一个概念，即在仔猪的胃和近端肠道中就地生成甘油二酯、甘油单酯和中链脂肪酸（MCFA）。已知MCFA具有很强的抗菌特性，但由于其令人厌恶的气味和味道，很难直接使用。通过就地生成MCFA可以克服这些问题。该概念在体外进行了测试，并在体内用安装了胃瘘管的仔猪以及在田间条件下进行了验证，包括对畜牧生产性能的影响，以经典的抗菌生长促进剂或有机酸作为阳性对照。此外，还综述了MCTAG和/或MCFA在营养和营养利用方面的代谢和饮食限制（例如对消化生理、肠道菌群、采食量、生产性能、胴体组成的影响）。讨论了天然十二指肠前脂肪酶活性的作用、原料中内源性植物脂肪酶活性的存在以及向饲料中添加外源脂肪酶的可行性，以优化该概念。本综述阐述了MCFA与常用抗菌剂在前肠对菌群（总菌群、革兰氏阳性菌群、革兰氏阴性菌群、潜在病原体）以及上皮形态和组织学的作用相似性。这些观察结果被认为是获得最佳生长性能的基础。此外，这些天然存在的抗菌剂对人和动物几乎没有毒性，也不会引起残留和交叉耐药性问题。它们被提议作为饲料抗生素的一种有价值的替代品，用于促进生长，甚至用于胃肠道疾病的预防和治疗。
