The Antibacterial Activity Of Cu²⁺-chitosan/montmorillonite Composite And Its Applied Effects In Broilers

Antibiotics take an important part in growth-promoting, diseases preventing and curing and feed conversion rate increasing. However, abuse or overuse of antibiotics causes various side-effects, which results in the emergence and increase of bacteria resistant to antibiotics and environmental contamination,and threaten human healthy.More and more countries prohibit using antibiotics. In order to ensure the good health of livestock and decrease economic lose,therefore, it's urgent to develop a new antibacterial material which can replace antibiotics as feed additive.Chitosan/montmorillonite composite was prepared with Na+ -montmorillonite and chitosan solution.X-ray diffraction indicated the chitosan molecules had already inserted into the interlayers of montmorillonite.The chitosan/montmorillonite composite and CuSO4 were used to prepare Cu2+-chitosan/montmorillonite (CCM) by chelateding. The nature exchangeable cation and intercalation of MMT and the function of sequestration of chitosan were used to prepare the nanocomposite, anticipate a kind of antibacterial materials that contains two active ingredients.Feed experiments were conducted to study the effects of CCM on growth performance, digestibility, microflora and intestinal morphology of Broilers.The research was conducted to determine the effect of CCM on the growth performance of Broilers and approach to the mechanism.Three hundred healthy 1-day old Avian Broilers were randomly divided into 5 treatments, each including 3 replicates (20 birds per replicate).The birds were fed with a corn-soybean based diet containing different treatment levels for 71 days. Control group was supplemented with basal diet,trails were supplemented with basal diet and 0.15% CSN for test 1,basal diet and 0.05%CCM for test 2,basal diet and 0.10%CCM for test 3 and basal diet and 0.15%CCM for test 4, respectively.All broilers were provided with light for 24 hours every day for the whole stage, feed and water were supplied freely. Thirty Broilerss(two Broilerss each replicate) were slaughtered and sampled on the 71th day. The results were as followss:1,The results of antibacterial activity showed:The antibacterial activity of CCM on common pathogenic bacteria was studied. The minimum inhibitory concentration and bactericidal concentration of CCM on E. coli, S. typhimurium and S. aureus were 0.270,0.135,0.135 mg/ml, respectively. The mechanism for the antibacterial activity of CCM may involve the enhanced affinity of CCM for bacteria and the antibacterial activity of Cu2+ ion, moreover, CCM contains two active ingredients, which may bring about synergistic effect and promote the antibacterial activity。2,The results of growth performance showed:(1) ADG,①In 0 to 21 day, supplementation with 0.15% CCM apparently increased the ADG (P<0.05)in contrast to the control, the ADG of 0.10% CCM and 0.15% CM group were improved(P>0.05);Compared with 0.10% CCM and 0.15% CM group,the 0.15% CCM group had a tendency to improve the ADG.②In 21 to 42d, supplementation with 0.15% CCM apparently increased the ADG (P<0.05) compared with the control, and supplementation with 0.15% CM had a tendency to increase(P>0.05);③In 42-71 day, supplementation with 0.15% CCM apparently increased the ADG (P<0.05) in contrast to the control, and addition of 0.10% CCM, and 0.15% CM had a tendency to increase, however had no significant difference(P>0.05);And addition of 0.15% CCM had a tendency to surpass the ADG of 0.10% CCM and 0.15% CM group.(2) Feed conversion ratio,①In 0 to 21 day, supplementation with 0.10 %,0.15% CCM和0.15% CM improved the feed conversion ratio significantly (P<0.01) and the feed conversion ratio of 0.15% CCM group was superior to 0.10% CCM group and had a tendency to be superior to the 0.15% CM group;②In 21 to 42 day, supplementation with 0.10%,0.15% CCM had a tendency to increase the feed conversion ratio (P>0.05);③In 42 to 71 day, supplementation with 0.10 %,0.15% CCM and 0.15% CM improved the feed conversion ratio significantly (P<0.05) in contrast to the control group, supplementation with 0.05% CCM improved the feed conversion ratio (P>0.05);In 0 to 71d, supplementation with 0.10% CCM and 0.15% CM had no significant influence on the ADG and feed conversion ratio.3,The results of digestion showed:(1)As compared with the control, supplementation with 0.15%CM had a tendency to improve the apparent digestion of DM,CP and EE (P>0.05), supplementation with 0.05%CCM had a tendency to inprove the apparent digestion of EE nd CP (P<0.05);supplementation with 0.10%CCM had sifinificantly improved the digestion of DM and CP(P<0.05) and had a tendency to improve the apparent digestion of EE (P>0.05); supplementation with 0.15%CCM had sifinificantly improved the digestion of DM, EE and Ca (P<0.05) and had a tendency to improve the apparent digestion of CP(P>0.05).(2) Supplementation with 0.15%CCM could (P>0.05) improve the apparent digestion of DM and EE in contrast to the 0.15%CM and 0.10% CCM group, and the apparent absorption of Ca increased with the rise of CCM concentration; Supplementation with 0.10%CCM had a tendency to increase the apparent absorption of Ca (P<0.05)compared with 0.05% and 0.10%CCM.4,The results of intestinal microecology showed:(1)As compared with the control group,①Supplementation with 0.15%CCM sifinificantly reduced the biomass of E coli and salmonella of small intestine contents (P<0.05), sifinificantly reduced the biomass of salmonella of cecum contents (P<0.05),had a tendency to degrade the biomass of the total cecum aerobic bacterial counts, increased the biomass of cecum bifidobacteria, however had no significant difference(P>0.05).②Supplementation with 0.15%CCM sifinificantly reduced the biomass of E coli and salmonella of small intestine contents and the salmonella of cecum contents(P<0.05),and sifinificantly increased that of lactobacilli and bifidobacteria of cecum contents(P<0.05).③Supplementation with 0.10%CCM sifinificantly reduced the biomass of the total aerobic bacterial counts, E coli and salmonella of small intestine contents and the total cecum aerobic bacterial counts (P<0.05), and sifinificantly increased that of lactobacilli (P<0.05),had a tendency to increase the biomass of cecum bifidobacteria and reduce that of salmonella, however had no significant difference (P>0.05).④Supplementation with 0.05%CCM reduced the biomass of E coli of small intestine contents and the total cecum aerobic bacterial counts, and increased the biomass of lactobacilli (P>0.05).(2) Compared with other group,①As compared with the 0.10CCM group,0.15%CCM group reduced the biomass of salmonella of cecum contents(P>0.05);Compared with the 0.10CCM group,0.15%CCM group updegrade the biomass of bifidobacteria of cecum contents(P>0.05).②As compared with the 0.15CM group,0.15%CCM group reduced the biomass of E coli of small intestine contents(P<0.05),and significantly increased the biomass of bifidobacteria of cecum contents(P<0.05),and increased the biomass of lactobacilli of cecum contents(P<0.05).③The biomass of the total aerobic bacterial counts, salmonella, lactobacilli and bifidobacteria had no significant difference between 0.15CM and 0.10%CCM group.5,The results of small intestine contents digestive enzyme showed:(1)As compared with the control,①The 0.15%CCM group significantly improved the activities of protease, trypsin,amylase, and chymotrypsin (P<0.05),and had a tendency to increase the activities of lypase.②Addition of 0.10%CCM significantly improved the activities of lypase and chymotrypsin (P<0.05),and increaded the activities of trypsin.③Supplementation with 0.05%CCM significantly improved the activities of protease(P<0.05), and had a tendency to improve the activities of lypase.④Supplementation with 0.15%CM significantly improved the activities of chymotrypsin and amylase (P<0.05).and had a tendency to improve the activities of lypase and trypsin.(2) Supplementation with 0.15%CCM significantly improved the activities of protease in contrast to the 0.10% CCM and 0.15% CM group; The activities of chymotrypsin of 0.10%CCM group was higher than 0.15% CM group,and amylase was lower than 0.15% CM group.6,The results of intestinal villus showed:(1)Supplementation with 0.15%CCM apparently improved length of villus as well as the V/C rate in duodenum, jejunum and ileum; Supplementation with 0.10%CCM apparently improved length of villus in duodenum, jejunum and ileum, as well as the V/C rate of duodenum and ileum; Supplementation with 0.05%CCM apparently improved length of villus in jejunum and ileum as well as the V/C rate of ileum;Supplementation with 0.15%CM significantly improved length of villus in duodenum, jejunum and ileum,as well as the V/C rate of ileum.(2) The 0.15%CCM group was significantly superior to 0.10% CCM group in length of villus in duodenum and the V/C rate of jejunum, and had a tendency to improve the length of jejunum;Supplementation with 0.15%CCM significantly increased villus length of jejunum and the V/C rate of duodenum,and had a tendency to improve length of duodenum and the V/C rate of jejunum. There were no significant differences between the 0.10% CCM and 0.15% CM group.7,The results of intestinal microvillus showed:(1)As compared with the control, Supplementation with 0.10%,0.15% CCM and 0.15% CM significantly increased the length and density of intestinal microvillus (P<0.05);Supplementation with 0.05%CCM increased the length and density of intestinal microvillus(P>0.05).(2) Addition of 0.15%CCM significantly increased the density of intestinal microvillus in contrast to other three groups; There were no significant differences in the length and density of intestinal microvillus between the 0.10% CCM and 0.15% CM group.The results above suggested that CCM exhibits antibacterial activity. It can effectively inhibit the growth and proliferation of pathogenic bacteria and promote the growth and proliferation of beneficial bacteria in the intestinal tract.and promote the digestion and absorption of dietary nutrition, adjust intestinal micrlflora, and improve intestinal morphology. All the results showed that CCM had a positive effects on the growth performance of Broilers.