发酵豆粕缓解断奶仔猪腹泻的机理研究

断奶仔猪腹泻是导致仔猪生产性能下降甚至死亡的主要原因，大肠杆菌是引起断奶仔猪腹泻的主要病原微生物。添加抗生素是最有效的缓解断奶仔猪腹泻的方法，然而抗生素的使用必然会增加病原微生物的耐药性。前期研究表明，用发酵豆粕替代日粮中的豆粕，可以提高断奶仔猪的生长性能及营养物质消化率，减轻肠道损伤，对腹泻有一定的缓解作用。因此、本研究在已有工作积累的基础上提出，以大肠杆菌K88攻毒断奶仔猪为体内模型，研究饲喂发酵豆粕对断奶仔猪生长性能、腹泻率、肠道菌群和食糜中大肠杆菌肠毒素水平的影响；同时以猪肠上皮细胞系IPEC-J2为体外模型，研究发酵豆粕提取物对大肠杆菌K88的生长、肠毒素的分泌和对肠道上皮细胞粘附的影响。根本目的是研究发酵豆粕缓解仔猪腹泻的机理，从而为提高断奶仔猪健康和降低抗生素的用量提供理论依据。

Enterotoxigenic Escherichia coli (ETEC) is a major problem in the swine industry and results in scouring, increased mortality, and poor performance in the period postweaning. The traditional way to control this problem is to include subtherapeutic antibiotics in feed, however, this enhance the risk of antibiotic resistance. Beneficial effects for fermented soybean meal have been reported in improving growth performance, nutrient digestibility and intestinal morphology and reducing diarrhea incidence. On the basis of accumulated relevant work, this project is proposed to study the mechanism of diarrhea control by fermented soybean meal in vivo and in vitro, so that the health and productive performance of weanling piglets could be improved and the antibiotic could be replaced. The effects of fermented soybean meal on diarrhea incidence, microbiota composition and enterotoxin concentration in digesta of weanling piglets after E. coli challenge are investigated. Adhesion of E. coli to the intestinal epithelial cells (IPEC-J2), secretion of E. coli enterotoxin and growth of pathogenic E. coli are studied. Sciences and technologies of animal nutrition, molecular biology, RT-PCR, denaturing gradient gel electrophoresis (DGGE) and phase contrast microscopy is to be adopted.