| In our research, we modified montmorillonite, zeolite and vermiculite with copper ions or quaternary ammonium salts, then examine the antibacterial effect on E. coli and S. suis. The in vitro study mainly include the adsorption regularity of DODMAB-MMT on E.coli and S. suis, and effect of temperature(15℃-37℃), pH (3-11) and oganic matters (0.5%-2%) on the adsorption rate. In animal experiment,210 7-day-old broilers were divided into the following 7 groups according to their initial weight:l)basal diet; 2) basal diet+0.2% MMT;3) basal diet+0.5% MMT;4) basal diet+0.2% Cu-MMT;5) basal diet+0.5% Cu-MMT; 6) basal diet+0.2% DODMAB-MMT;7) basal diet+0.5% DODMAB-MMT. The effect of adding montmorillonite or modified montmorillonite to broiler's on growth performance, deposition of micro metallic elements and calcium and phosphorous, amount of microorganism in small intestines and cecum were studied..The main results were as follows:In vitroThe adsorption rate of montmorillonite, zeolite and vermiculite on E.coli and S. suis were low(10-15%), however, adsorption rate were largely increased after modification, DODMAB-MMT has the highest adsorption rate(>95% of both bacterials) among all modified clays.The adsorption rate increased when the medium temperature rised, as well as the medium pH far from pH=7, and the concentration of organic matter decreased. In acertain concentration of bacterials, the adsorption rate increased with the elevated concentration of bacterials. Nevertheless, if concentration of bacterials continue rising, adsorption rate would decrease.High concentration of DODMAB-MMT in soil has antibacterial effects on E.coli and S. suis, which indicated that DODMAB-MMT has the potential of being used as antibacterial agents for soil.Animal experimentResults of in vivo study mainly involve three impacts:growth performance, deposition of micro metallic elements and calcium and phosphorous, amount of microorganism in small intestines and cecum. Growth performance:Montmorillonite (0.2-0.5%) had no effect on ADFI, ADG and F/G in broilers(P>0.05). Add of 0.5%Cu-MMT increased F/G in broilers significantly (P<0.05). DODMAB-MMT(0.2-0.5%) had no effect on F/G in broilers(P>0.05).Deposition of Zn,Fe,Cu,Mn,Ca and P:Cu-MMT(0.5%) and DODMAB-MMT(0.2-0.5%) increased Zn concentration in liver (P<0.05). Cu-MMT(0.5%) decreased Zn,Fe and P concentration in tibia (P<0.05). DODMAB-MMT(0.5%) also has a tendency to decrease Fe and P concentration in tibia(P>0.05).Microorganism in small intestines and cecum:No significant effect was found in total aerobic bacteria,total anaerobic bacteria,E.coli and lactic acid bacillus count in small intestines and cecum(P>0.05).Conclusions:The above results indicate that the adsorption rate of montmorillonite, zeolite and vermiculite on E.coli and S. suis were low and much higher after modification. Temperature, as well as the medium pH and the concentration of organic matter, all can affect the adsorption rate of DODMAB-MMT. DODMAB-MMT in soil has antibacterial effects on E.coli and S. suis as the concerntration were over 25mg/g or 50mg/g, seperataly. When adding 0.2%-0.5% MMT or Cu-MMT or DODMAB-MMT to broilers'feed, no effects on microorganism in small intestines and cecum were found, however, deposition of minaral elements may decrease. |
