| Antibiotics and high copper have been used as growth promoters in animal production as well as their conventional use in therapy. Antibiotics resistance is now recognized as a major threat influencing our ability effectively to treat a range of diseases in human and animals. Moreover, both high copper and resistant bacteria may be excreted by animals and then spread in the environment which caused health harmfulness and environmental pollution. This article purposes is to develop a newly nano-feed additives which apply to animal production to solve these problems which above mentioned. In the present work, silicate as a vector, Cu(II)-exchange silicate was constructured by cation exchange reaction and connected with nano-technology to produce Cu(II)-exchange silicate nanoparticles(CSN). Four bacteria as indicators of intestinal tract of weanling pigs. Feasibility and possibility of antibiotics to be substituted were analyzed and investigated by Caco-2 cells culture, in vitro adsorption and bactericide and feeding trail.Adhesion and colonization properties of four strains in weanling pigs namely, E. coli ATCC K88, S. choleraesuis ATCC 50020, L. acidophilus ATCC 4356, and B. bifidum ATCC 15696, were determined in vitro using enterocyte-like Caco-2 cells. I also investigated the effect of LSN and CSN on Caco-2 cells, adhesion and invision of four bacteria on Caco-2 cells, and on intestinal mucosa.In this study, in vitro I investigated the characteristics of LSN and CSN. Then study on the adsorption of four bacteria onto the surfaces of two nanoparticles, LSN and CSN, as a function of time, particle size, pH, ionic strength, temperature, and bacteria: nanoparticles mass ratio, and approach to the mechanism.In vitro the bactericide activities of LSN and CSN were also investigated by determining the minimum inhibitory concentration (MICs), "halo" assay and modified vibate flask assay which as a function of contact time, concentration, particle size, and temperature. And antibacterial mechanisms were evaluated by structural integrity of cell walls of bacteria, enzymes activity, the rate of oxygen consumption, K+ efflux, and released Cu2+, etc.In feeding trial, 45 days experiments involving 160 crossbred pigs(Duroc X Landrace X Yorkshire) weaned at 28 + 2d of age (initial weight,7.5 + 0.3kg)were conducted to investigate the effects of 0.2% and 0.3% CSN, aureomycin, copper sulfate on the growth performance, intestinal microflora, enzymes activities of duodenum and pancreas, mucosa disacchridase activities and morphology of intestinal tract, and approach to the mechanism. Pigs were allotted into five groups based on sex, litter and weight, each of which was replicated four times with eight pigs per replicate. The five dietary treatments were basal diet (control group), basal diet + 250mg/kg of Cu, basal diet + 100mg/kg aureomycin , basal diet +2g/kg CSN, basal diet +3g/kg CSN. Theresult is shown below.1. The results of Caco-2 cells culture trial shown that all four bacteria showed a high ability of strong adherence to Caco-2 cells in vitro. Adherence were 12.2%, 11.7%, 15.6%, and 17.7%, respectively. It indicated that adherence of E. coli K88, S. choleraesuis was lower than L. acidophilus and B. bifidum(P<0.05). When the adhesion of enterotoxigenic strains to Caco-2 cells, caused decreasing significantly to viability .and proliferation of the cells. At viability, no differences were observed in the probiotic strains, but proliferation of the cells increased significantly (P<0.01).2. The results of toxicological of cells trial shown that the concentration of 1g/L LSN, 0.02g/L CSN was the most suitable to growth of Caco-2 cells. It indicated that nanoparticles were compatible with cells.3. When the adhesion of enterotoxigenic strains to Caco-2 cells 1h, caused releasing greatly LDH from cells, the LDH activity decreased significantly compared to control activity (P<0.01). ALP activity decreased significantly compared to control activity (P<0.01). In contrast to these effects, when the adhesion of probiot...
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