Adaptation To Different Types Of Fiber In Growing-finishing Swine And Changes Of Hingut Fermentation And Microbiota

The problem feed resourses shortage becomes more seriously with the rapid development ofanimal husbandry in China. Many by-products of Grain, oil and food industry with high fiber contentare used in pig diets increasingly. It is very important and significant to improve fibers degradation rateof these by-products in pig hintgut and to make full use of its potential energy for improving pigproductivity and eviation of feed resource shortage problems. In this thesis, experiments were designedto study the adaptation to semi-purified diet with high different types of fiber and the effects of differenttypes of fiber on pig hindgut microbiota and fermentation characteristics, to probe into the key factorsinfluencing fiber utilization by growing-finish pigs and guide application of different types of fibers inpig diet. At the same time, cellulose-degrading bacterias from the pig large intestinal was isolated andcharacterisated to provide meterials for studies of fiber degradation regulation in vitro.Adaptation to different types of diary fiber in growing-finishing pigs. Twelve pigs(80±2.5kg) wereassigned to three different semi-purified basal diets supplemented with wheat bran, soybean hull or cornbran. The apparent digestibility of diary fiber were mearsured during2,4,6weeks. Fecel samples fromday15,30,45were collected for determination of xylanase and cellulase enzyme activities. DGGE andRT-PCR were used to evaluate changes of microbial communities.The results of the test are as follows:with extension of feeding time, NDF digestibility of wheat bran and corn bran increasing significantly(P<0.05). NDF digestibility of soybean hull didn’t change(P>0.05); ADF and cellulose digestibility ofthe three fibers significantly increased (P<0.05). but hemicellulose digestibility of the three fibersdidn’t change(P>0.05). NDF、ADF、cellulose and hemicelluloses digestibility of soybean hull werehigher than wheat bran and corn bran(P<0.05).This showed long time may be necessary forgrowing-finishing pigs to digest wheat bran and corn bran and short time to digest soybean hull.Xylanase and cellulase enzyme activity didn’t change over time(P>0.05). PCR-DGGE profiles showeddensity of some bands changed with time, and sequens analysis showed this bands belong toClostridiaceae、Lachnospiraceae、Veillonellaceae、Lactobacillaceae、Oscillospiraceae、Bacteroidaceae、Porphyromonadaceae、Prevotellaceae and Brachyspiraceae bacterium. Types of diary fiber also greatlyinfect microbial communities. Real-time PCR results showed the quantity of Lactobacillus spp.,Ruminococcus albus and Ruminococcus obeum significantly changed(P<0.05).The quantity ofLactobacillus spp., Ruminococcus albus and Ruminococcus obeum of Wb and Cb were higher thanSh(P<0.05). The changes of microbes also show growing-finishing pigs need time to adapt high fiberdiets and the time needed depended on the types of diary fiber. Soybean hull may be better forgrowing-finishing pigs.The effects of types of diary fiber on hingut fermentation. After7weeks, pigs were sacrificed andcaecum, colon and rectum contents were collected for determination of pH、volatile fatty acid (VFA)concentration and xylanase and cellulase enzyme activity, DGGE and RT-PCR were used to evaluatemicrobial communities. Results showed that the pH of Sh in the colon was lower than Wb andCb(P<0.05).The Total VFA concentration of Sh were higher than Wb and Cb(P<0.05); The changes of Acetate、Propionate、Butyrate were similar with Total VFA. The results indicated soybean hull. wereHighly fermentated by growing-finishing pigs. Fiber types also had a significant effect on xylanase andcellulase enzyme activity (P <0.01).The enzyme activity of Sh were significantly higher than Wb andCb. PCR-DGGE profiles and sequencing results showed that Sh has relatively richer bands than Wb andCb. Real-time PCR results show that fiber types effect the quantity of Rumincoccus flavefaciens、Fibrobacter succinogenes and Clostridium cluster IV(P<0.05).The segment had significant effect on thepH、VFA concentration and xylanase and cellulase enzyme activity and microbial communities. Thismay be caused by different fiber had different fementation segment. These results indicate that fibertypes have a significant impact on the pig large intestinal microorganism fermentation.Indicating thatregulating the composition of the fiber in the diet to regulate hingut fermentation. Soybean hull have abetter fermentation characteristics and can be added in growing-finishing pig diets.Isolatation, identification and fiber-degrading ability of fiber-degrading bacteria from pig hingut.An anaerobic xylan-degrading bacteria was isolated from pig hingut digasta and named M9. Lightmicroscopy revealed the cells of M9were rod-shaped, Gram positive and had spores. M9was identifiedas Clostridium sp..by16S rDNA sequence analysis and API20A anaerobe identification system. Whencultured in xylan, wheat bran, corn bran or soybean hull medium, the xylanase activity of M9didn’tchange obviously within24-96h, but increase rapidly within96-108h. The NDF and ADF degradationrate of wheat bran, corn bran or soybean were measured. With the extension of fermentation time, NDFand ADF degradation increased. M9showed high NDF and ADF digestion rate to wheat bran, indicatedthat M9has strong fiber degrading characteristics.