| Chitosan is the only edible animal fiber with cation in the nature, and is the sixth basal nutrition (protein, sugar, fat, vitamin and minerals) .It is called a type of new additives which has the effectiveness of antibiotic activity, antivirus activity, adjusting metabolism of fat and improving immunity and so on. The experiment was conducted to study the effect of the different concentration of chitosan on performance, availability of nutrition and immunological function by feeding trial, metabolic trial and slaughter trial. And the antibacterial effect of chitosan with different concentration and different deacelylated degree against chicken pathogenic bacteria in vitro was studied.120 Arbor Acre broilers (1d of age) were randomly divided into five groups, with three replications per group, and per replication was eight broilers. The control group ( Group â… ) was fed with corn-soybean meal basal diet, the trial groups ( Group â…¡, â…¢, â…£ and â…¤ ) with basal diet plus 10g/kg, 20g/kg, 30g/kg chitosan, and 5mg/kg Flavomycin, respectively. The raising period is seven weeks. Weights, gains and feed intakes of every replication were weight every weekend, and average daily gains, feed intakes and feed efficiency were calculated. The result showed that from 1 to 49 day, daily gains of all groups were 48.73g, 45.86g, 44.01g, 45.60g, 48.85g, respectively. Chitosan supplement decreased daily gains ( p < 0.05 ) and feed intakes ( p > 0.05 ) during the whole growing stage, and there was no difference between chitosan groups ( p > 0.05 ) . Daily gains and feed intakes of Flavomycin group were higher than these of chitosan groups and the control group. During every raising stage, from 1 to 21 day, daily gains of groups were 29.26g, 28.83g, 26.07g, 25.75g, 29.65g respectively. Daily gains and feed intakes of chitosan 10g/kg group had no difference with the control group, these of â…¢,â…£ groups decreased significantly ( p < 0.05 ) . From 22 to 49 day, daily gains of groups were 63.34g, 58.64g, 57.47g, 60.48g, 63.26g ,respectively. Daily gains of â…¡, â…¢ group were lower than the control and Flavomycin groups significantly ( p <0.05) .Metabolic trial began from 17d to 21d. The result showed that in contrast with the control and Flavomycin groups, chitosan supplement decreased differently availability of energy , protein , calcium and phosphorus , but there was no difference between chitosan groups ( p > 0.05 ) .At 2 Id, 35d and 49d, blood samples were obtained from one broiler of each group to measure T lymphocytes percentage, T lymphocytes blastogenic response to ConA in blood, HI titers, IgA, IgG, IgM in serum and indexes of immune organs of Thymus gland, Bursa of Fabricius and spleen. The result showed that chitosan supplement had no difference on indexes of thymus gland, Bursa of Fabricius and spleen. Chitosan supplement improved T lymphocytes percentage, and it had an increased current with the increase of supplement. In the whole growing stage, chitosan supplement improved HI titers; serum Ig had an increased current with the increase of chitosan supplement at 21d,but there were no difference at 49d.The influence of chitosan with different concentration and different deacelylated degree were observed on the growth of chicken pathogenic bacteria cultured in vitro with Agar Pervasion Paper Method The experimental results demonstrated that four chicken pathogenic bacteria (Escherichia coli, Salmonella pullorum, Staphylococcus aureus, Pasteurella multocida) could be inhibited to different degrees by chitosan. The antibiotic activity of chitosan with the same deacelylated degree was enhanced with the increase of concentration of chitosan, and showed the best in the concentration from 2% to 2.5%. The antibiotic activities of three descelylated degree chitosan was enhanced with the increase of descelylated degree.Chitosan inhibited the growth of Pasteurella multocida more effectively than other three pathogenic bacteria. |
