The Nosogensis Of Diarrhea And Regulation By Bio-Active Substances On Weanling Rabbits

The enteritis and diarrhea of the weanling rabbits have become a big problem when the number and the size of the warren have been increased in china, especially, for the poor management practices farms in our country, the mortality of young rabbit reaches 50%~70% , 80 percent of which is diarrhea disease-causing. During farm operations, antibiotics generally are used to treat the diarrhea, which not only results in drug residues in meat or milk, but also have negative effect on the rabbits Solving the big problem of the warren has become a research interest due to the possible health benefits afforded humans consuming meat.Our objectives were to determine the mechanism and pathogenesis of the weanling diarrhea and find bio-active substances to substitute for antibiotics. Three trials were involved in the research: First, ascertain the diarrhea pathogenesis for weanling rabbits that were low fiber level in diet, antibiotics-inducing, stress of feed change and pathogen contaminated; Secondly, discussing the mechanism of the weanling diarrhea including its beginning, development and animal's death, according to the change of cecum microorganism, test for blood physiological and biochemical index, the change of pH value and content of alimentary tract; Thirdly, to ensure the diarrhea can be effectively controlled, three fields were planed to study and reached such targets that the nosogenesis can be determined, pathogenesis found, and biological regulating way, according to further nutritional regulating ways that included Bifidobacterium preparation, complex preparation of probiotics, oligosaccharides, allitridum and so on.Analysis of dietary data suggested the correlation between fiber level in diet and the incidence of the diarrhea is negative. The diarrhea can be induced for the weanling rabbit fed the diet with low fiber levels (CF7% and CF9%). The 12% fiber level in ration for the weanling rabbit was recommended considering the gain per day, the ratio of feed to weight, nutrients digestive rate etc.The nitrogen free extract increased in cecum content to some extent for the weanling rabbit having diarrhea induced by low fibber diet, which partially supports Cheeker-Patton theory "intestine overload of carbohydrate", but in the condition of strict controlling sanitary environment and coccidiosis, only did the mucous enteritis happen with low fiber diet. We believed some changes occurs in the digestive tract (the starch contents in cecum, VFA, pH etc.) under the low fiber diet condition, which led that the animal was more susceptible to pathogens (salmonella, colibacillus and Clostridium perfringens etc.) infection and proliferation, and normal microbial clump had altered, which made the weanling rabbit sub-clinical state. The enteritis and diarrhea would erupt under the circumstance of poorsanitary environment, cocci to invade and external stress.The diarrhea can be induced for the weanling rabbits by low fiber diet, feed contaminated and feed abruptly altered or ampicillin drinked with large dosage. The diarrhea incidence reached from 45% (when CP/o diet fed) to 80% (when CP/o diet fed) as we fed the every weanling rabbit 0.2g /d cecum contents of the ill (contained colibacillus 632000 pfu, Clostridium perfringens 79600 pfu); The diarrhea incidence can reach 75% to 100% with the oral dosage 600KJU/day/rabbit ampicillin; the diarrhea occurred for all rabbit when two diets changed alternatively between CF10% and CF14%. Four factors above were main reasons to diarrhea of the weanling in rabbitry.The diet with low CF led to a severe decrease in the amount of useful microorganism including Bifidobacterium, Bacteriodes, lactobacillin and digestive cocci, and a increase in the amount of colibacillus and salmonella, an disorder in normal flora. It was concluded that the optimal flora ratio of Bifidobacterium, Bacteriodes, lactobacillin and digestive cocci to E. coli for healthy weanling rabbit were 17:1, 100:1, 12:1 and 20:1, respectively. The diarrhea can be induced by feed contaminated and abrupt change or ampicillin for the weanling rabbit, and the beneficial microorganism above decreased greatly in cecum, those adverse effects ampicillin brought most, and sequentially the feed contaminated, feed abrupt change. The harmful microorganism such as E.coli and Clostridium perfringens increased markedly. The benefitful microorganism was related negatively to the harmful. Intestinal flora disorder resulted from the different factors was main reason for diarrhea.The pH value in digestive tract increased usually when rabbit suffered from diarrhea, which was not only the result of digestive disorder, and signs of intestinal microbial disorder. It supplied better environment for the proliferation of the harmful microorganism.For diarrhea resulted from low fiber diet, probiotics made the best curable effect, EM, ollicin and olligofuctose in sequence. No co-operated effect existed between two active substances between probiotics, ollicin and olligofuctose to prevent the illness. It had different effects for diarrhea caused by different factors, which decreased diarrhea rate induced by ampicillin and polluted feed at 15%, 20 to 40%, respectively. It suggested that 0.2% probiotics prevent the weanling rabbit from diarrhea induced by feed abrupt change. The research can supply theoretic and practical support for safe rabbits production.The probiotics and bifidobacterium ado lescentis had special effects on diarrhea resulted from low fiber diet with 98% and 100% curable rate. It produced certain effect on the illness by abrupt change in feed, polluted feed and ampicillin with different addition level of probiotics, and the curable rate was related to dosage. When 7.5 ml probiotics was injected per rabbit each time, the cure rate of three kinds of diarrhea was 76.92%, 68.18% and 0.71%, respectively. The research can supply theoretic and practical evidence for antibiotics replaced by probiotics in rabbit and others.Such serum indices for the ill rabbit increased as alkaline phosphatase, glutamic-oxalacetictransaminase (GOT), glutamic-pyravatic transainase (GPT) and urea nitrogen to some degree compared with the healthy; The more serous diarrhea was, the more severely the viscera of rabbits damnified, further the serum indices ascended. So these can be a sort of signs of weanling rabbit's organ damnification as a biological diagnosis way.The author made a series of pathology image by systematical study on pathogen dissection and nosogenesis regulation to provide reference to diagnosis of diarrhea.