| Experiment 1:Chinese Yam Polysaccharide(CYP) was selected as additive,and CYPF1,CYPF2,CYPF3 and CYPF4 were extracted from the Chinese Yam Polysaccharide with water-extracting-ethanol-precipitation method,when the end concentrations of the ethanol were 30%,45%,60%and 75%,respectively.And in this period,trichloracetic acid was used for deproteinization.Their contents(%) assayed by vitriol-anthracene ketone were 45.85,56.24,90.91 and 13.87,respectively.In addition,the protein content of the CYPs were 2.62%,2.71%,2.81%and 2.53% respectively,which were determined by the coomassie brilliant blue G-250 method (Bradford method).The four polysaccharides were prepared for the whole study.Experiment 2:The present experiments were conducted to determine the fermentation characteristics of four fractions of Chinese Yam Polysaccharides(CYPF) in vitro by evaluating the difference of fermentation kinetic parameters and fermentation productions among different CYPFs in order to investigate the possibility of CYPFs as functional dietary additives used in domestic animals and poultry.CYPF1,CYPF2,CYPF3 and CYPF4 were extracted from the experiment 1. Cecal digesta collected from SD rats fed normal diet was used as the inoculums and the four polysaccharides were used as the substrates during the in vitro fermentation. The slurry was fermented for 36 h in an anaerobic in vitro system,and then the fermentation kinetic parameters,pH value,NH3 content,production and composition of short-chain fatty acids(SCFA) in the fermentation broth were determined,in addition,DNA of the bacterias in the fermentation broth was extracted for PRC-DGGE course.Our data showed that the maximum volume and rate of gas production in CYPF3-supplemented group was higher(p＜0.05) compared with the other CYPFs-supplemented group and free-supplemented group,while the pH value and NH3 content in CYPF2,CYPF2 and CYPF3-supplemented group were lower extremely compared with free-supplemented group(p＜0.01).Contents of acetic acid and butanoic acid in the CYPF3-supplemented groups was higher compared with the other groups(p＜0.05),while of propionic acid and isobutanoic acid were lower compared with CYPF3-supplemented group.In addition,the contents of acetic acid, propionic acid and butanoic acid had correlation(p＜0.05) with pH value and NH3 content.Denaturing gradient gel electrophoresis analysis showed that CYPF3- and CYPF4-supplemented groups have high similarity(91%),and the microbial population of total anaerobic bacteria of increased and the microbial species decreased after in vitro fermentation.Collectively,CYPF3 and CYPF4 may be a good source of carbon and energy,and therefore modulate SCFA production patterns in hindgut of the SD rats.Experiment 3:The effect of Chinese Yam Polysaccharide on the growth performance and immune function of Sprague dawley(SD) rats were investigated in this study.The 40 male SD rats with 87±3 g body weight were assigned randomly to 4 groups(n=10).Groupâ… was fed with basal diet.Groupâ…¡,â…¢andâ…£diets were formulated based on groupâ… diet supplemented with 0.25g/kg,0.5g/kg and 1.0g/kg Chinese Yam Polysaccharide(CYP3) respectively.The data suggested that:1) compared with control groups,ADG of groupâ…¡was higher(p＜0.05) in two experiment periods,feed weight ratio was lower(p＜0.05) in the third week.And the growth performance was decreased following the elevation of Chinese Yam Polysaccharide supplementation in the diets.2) compared with control groups in two experiment periods,the level of serum IL-2 and TNF-αof groupâ…£were higher (p＜0.05),and the level of serum IL-2 and TNF-αin four groups was enhanced following the elevation of Chinese Yam Polysaccharide supplementation in the diets; however,the level of serum LDL,TC and TG of groupâ…£were lower(p＜0.05),and the level of serum LDL,TC and TG in four groups was decreased following the elevation of Chinese Yam Polysaccharide supplementation in the diets.3) compared with control groups in two experiment periods,the OD value of groupâ…¡was higher (p＜0.05),and the OD value was decreased following the elevation of Chinese Yam Polysaccharide supplementation in the diets.4) In the first week of experiments,the contents of Acetic acid and Butanoic acid in cecum chyme of Groupâ…¡andâ…¢were higher than the control group and groupâ…£(p＜0.05),and the content of propionic acid in cecum chyme of Groupâ…¡was higher than the other groups(p＜0.05).In the third week of experiments,the content of Acetic acid in cecum chyme of Groupâ…¡was highest in the all groups(p＜0.05).5) With the DGGE,we could find that the brightness of land about Lactobacillus salivarius and Bacillus subtilis were higher than the control group,and the amount of dominant bacterium clot in all groups supplemented with Chinese Yam Polysaccharide increased with the extend of experiment period,moreover,the comparability of repetition in the treats enhanced a little.The results of our research may suggest the 0.25 g/kg Chinese Yam Polysaccharide supplementation can enhance the growth performance and immune function of SD rats.Furthermore,the Chinese Yam Polysaccharide could be used by SD rats,which could change the cecum microbe zoology and the constitute and content of SCFA of SD rats.
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