Comparative Study On Digestive Dynamics And Antinutritional Effects Of Soybean Agglutinin In Different Species Of Animals

Four experiments were conducted to investigate the digestive dynamics and antinutritional effects of soybean agglutinin(SBA) in different species of male animals aged middle maturity (sheep as ruminant, dog as carnivore, rabbit as rodent, pig as omnivore and chicken as fowl), as well as purification and determination of SBA inbefore.Samples of pure SBA were prepared by N-acetyl-D-galactosamine- epoxy-sepharose6B affinity chromatography system and Guar affinity chromatography system. The purity(identified by SDS-PAGE) and biotic activity(characterized by hemagglutinining) of the SBA were equal to the standard SBA. The yields and absorbing capacities of the two systems were significantly different (P＜0.05). It showed that N-acetyl-D-galactosamine -epoxy-sepharose 6B affinity chromatography system was better than Guar system to prepare SBA. The polyclonal antibody of rabbit to SBA were made and the quantitive determination method—indirect inhibiting ELISA were established. The lowest limit of the determination was less than 10ng/mL with credible sensitivity, which could meet the need of the studies.Survival rate of SBA in the chyme within different parts of digestive tracts of different species of animals were tested. Animals were fed on diet containing 20% raw soybean and 1%Cr₂O₃ (as exogenous indicator). Two hours after the last meal of two weeks' feeding, the chymes in duodenum, front-jejunum, middle-jejunum, behind-jejunum, ileum, appendix and colon were sampled and stored in—20℃. SBA in the chymes and feeds were detected by ELISA, and total Cr in the chymes and feeds were detected by atomic absorption spectrometry. The results showed that SBA existed in all of the parts of digestive tracts, while survival rates of SBA in different parts showed a downtrend from duodenum to colon. The survival rates from duodenum to front-jejunum were significantly different (P＜0.05) in all of the five speices. There were differences for survival rates in the same parts of digestive tracts in different species. Rabbit possesed the lowest rates in all the parts. Sheep and chicken were higher than pig and dog from duodenum to behind-jejunum. Pig, sheep and chicken showed higher survival rates than the others in ileum, appendix and colon.Degradation of SBA under simulated gastric/intestinal environments were tested. SBA of different concentrations (1, 2, 3, 4 and 5mg/mL) were mixed iso-volume with the simulated gastric/intestinal fluids(37℃) and the reactions were terminated at different times(15s, 30s, 60s, 2min, 4min, 8min, 15min, 30min and 60min). The SBA left in the system were detected by the two methods of SDS-PAGE and ELISA established in experimentâ… . The results showed that the pepsin hydrolyzing SBA took place mainly at the initial phases of reaction and the speed of degradation turned down as the time going, but the reactions were going on constantly. The degradation speed increased with the concentration of SBA from 1 mg/mL to 5mg/mL, but longer times were needed for thorough degradation. Times for thorough degradation distributed from 9.5min to 25min. Trypsin showed no degradation effect on hydrolyzed SBA.SBA of different concentrations(0.5, 1.0and 3.0 mg/mL) were injected into intestinal loops of the five species of animals under anaesthesia in order to study the binding, absorption and survival of SBA in jejunum and its effects on intesrinal tissues. The results of binding, absorption and survival rates were different among species. Rabbit showed the highest absorption and the lowest survival rate. On the contrary, sheep possesed the highest survival rate and the lowest absorption rate. It showed similar situations in chicken to rabbit, but rabbit possesed lower survival and higher absorption than chicken. Compared to chicken and rabbit, pig and dog showed higher binding and lower absorption capacity. All the pecies showed stronger capacity of absorption under lower concentrations of SBA.The results of this study indicated that there are different survival rates in different species of animals and in different parts of intestinal tracts. The facts that the SBA disappeared faster from duodenum to jejunum showed that absorption, binding and/or degradation of SBA in all the five specis took palace mainly in the front parts of intestines. SBA can be degraded by pepsin in certain degrees, but time is needed. Trypsin do not degrade complete SBA. The sensitivity and tolerance of intestinal mucosa to SBA were different among species. Ruminant is less sensitive to SBA than the others. However, the abilities of absorption and binding to SBA in mono-stomach species are stronger than that of ruminant. Permeability of the intestinal mucosa of rabbit is the highest in the mono-stomach animals because of its strongest absorption, so it is easy to arise the antinutritional effects caused by absorbing SBA. The tendency of chicken is similar to rabbit, however, the ability to absorption SBA of the intestinal mucosa is lower than that of rabbit. Pig and dog have lower permeability and higher specific bindings to SBA, therefore, it is easy to make the antinutritional effects caused by binding SBA. The degrees and mechanisms of antinutritional effects of SBA are incompletely different among different species.