Untersuchungen zur Wirkung nichtantibiotischer Futterzusätze auf die Darmflora sowie den Verlauf einer experimentellen Escherichia coli- bzw. Salmonella Derby- Infektion bei Schweinen

Aim of the present study was to investigate the effect of 0,5% coated acid mixture (45% fumaric acid, 20% citric acid), 5% lactulose and 2,4% coated pancreatin on the composition on the gut flora in the last third of the small intestine and the ascending large intestine. During the investigation the experimental group (with feed additives) and the control group was fed over a period of 6 up to 15 days. The total number of aerobe and anaerobe microbial counts as well as some selected indicator counts (streptococci/enterococci, Escherichia coli, gram-negative anaerobic bacteria, lactobacilli and Clostridium perfringens) were analysed. The animals were sacrificed 6 hours after last feeding. In addition to this study , in the Institute of Animal Nutrition, School of Veterinary Medicine Hannover, STUKE (Diss. in prep.) measured pH, concentration of lipopolysaccharides, L-lactate, ammonia and volatile fatty acids of the samples to characterize microbial activity. The results of these tests have been compared to the data of bacteriological investigation. Non of the tested feed additives affected significantly the bacterial counts or the microbial colonization and activity of the intestinal flora. The weaner pigs showed tendency in reduced E. coli-counts in the last third of the small intestine by addition of lactulose (lg 5,1 opposite lg 7,1 /g) and coated pancreatin (lg 6,1 opposite 6,9/g) compared with the control group. During addition of lactulose the counts of bifidobacteria were measured in intestinal samples of experimentally infected pigs. But no stimulating effect on microbial counts of bifidobacteria was found. In a further step the influence of the mentioned food additives on the course of an oral infection by enterotoxemic E. coli-O139:K82, F18+ stock culture was investigated. The animals were fed over a period of 5 days and then infected by ca. 109 c.f. u. In this study the feed additives were given to half of the pigs whereas the control group got no feed additive. Counts of E. coli-O139:K82 were investigated every second day in samples of faeces. Until piglets either succumbed to colientertoxemia or at the end of the feeding phase of 8 up to 10 days they were euthanized. At that time intestinal samples were taken and microbial counts of the inoculated E. coli stock and the microbial activity was determined. No reduction of the E. coli-O139:K82 counts as well as the microbial activity was detected in the faeces and intestinal samples and the number of piglets showing clinical signs of edema disease were similar in treated and control groups. To check this model of infection a control group of 5 piglets got Colistinsulfat. Following this application of antibiotics an significant decrease in the number of E. coli-O139:K82 was detected in samples of faeces and intestinal contents and no piglet showed clinical signs of edema disease. In addition the influence of lactulose on the course of an experimental infection by Salmonella Derby culture was investigated. On day 2. p.i. the excretion of Salmonella Derby was 70-100% and 10-20% on day 13. p.i. The observation of Salmonella infected animals lasted from 14 up to 42 days. Salmonella Derby was investigated in samples of ileum, colon, tonsils, ln jejunalis and ln. ileocolicus. In more pigs of the treatment group (ileum: 100%; colon: 80%) than in controls (ileum: 20%; colon: 30%) Salmonella Derby was detected in samples of the small intestinal (part 3) and colon mucosa and chyme. The frequency of translocation of Salmonella Derby in lymph nodes was not reduced by addition of lactulose (treated group: 40%, control group: 10%)