SWEDISH UNIVERSITY OF AGRICULTURAL SCIENCES (SLU)
PhD studies supported by MEKARN
Dietary modulation to improve pig health and performance
Tran Thi Thu Hong
Hue University of Agriculture and Forestry
The aim of this thesis was to estimate the presence of Salmonella and enterotoxigenic Escherichia coli in piglets, the effect of fermented liquid feed and rice distiller’s residue as a dietary modulation of the microbial population, the presence of microflora at different sites of the digestive tract, digestibility, and to evaluate the performance of pigs under small-scale farm conditions. The first experiment showed that Salmonella and E.coli were found in faeces from piglets without and with diarrhoea. All E. coli antigens were isolated from piglets without and with diarrhoea. However, the frequency of antigen was much higher in piglets suffering from diarrhoea. Nutrient supply for sows and for piglets was low in comparison with feeding standards. In the second experiment, there were no differences in pH and butyric acid concentration of ileal digesta in pigs fed raw (R), cooked (C) or naturally fermented (F) diets. However, on diet F concentrations of acetic, lactic and propionic acid in ileal digesta were higher than on diets R and C. The ileal apparent digestibility of crude protein, crude fiber and NDF were higher in diet F than in diets R and C. The total tract apparent digestibility of crude protein was higher in diet F than in diets R and C. In conclusion, when compared with the diet in raw form, fermentation influenced the gut environment and improved the digestibility of some dietary components, while cooking prior to feeding had no measurable effects. In the third trial, a naturally fermental diet (FE) resulted in a lower pH than a diet basal on rice distiller’s residue (RDR). Diet FE contained more organic acids, and had the lowest counts of E. coli and total coliforms, and the highest counts of lactic acid bacteria (LAB). Piglets fed diets FE and RDR had lower pH, and higher concentrations of organic acids in the stomach, ileum and mid-colon than piglets fed diet CO. Counts of LAB in stomach and ileum were higher in animals fed diets FE and RDR compared with diet CO, while the number of E. coli and total coliforms along the gastrointestinal tract was reduced. The ileal digestibility of crude protein and organic matter was improved in piglets fed diet RDR compared with piglets fed diet CO. Piglets fed diet RDR had a higher weight gain and a better feed utilization than piglets fed the other diets. In the final experiment DGGE analysis showed that animals fed diet FE had a much more uniform microbial flora in the stomach and the ileum compared to the other diets. Strains belonging to the genus Pediococcus were found in stomach and ileum of piglets fed diet FE and not on the other diets which probably arose from the feed.