| This experiment was designed to study the influence of lysozyme and other three additives (nosiheptide, kitasamycin and chlortetracycline) on performance, quantity of microrganism coenobium in cecum and index of immune organ of duck, so as to accumulate more documents for applicating lysozyme extensively.This experiment consists of lysozyme antibacterial test and animal experiments. In antibacterial test, the inhibitory effect of different concentrations of lysozyme solution on Escherichia coli standards was tested and provided the reference of the percentage of lysozyme added in animal feeds.The animal experiment used single factor trial design. Add lysozyme and other three additives (nosiheptide, kitasamycin and chlortetracycline) into basal diet. Seven hundred and fifty ducks divided into five groups stochasticly, with three replications per group and fifty ducks per replication. The nutrition standard of basal diet was according to NRC (1994) standard. After31days, performance and index of immune organ were investigated. At the 21-day-old, 12 ducks per group were selected randomly, and the quantity of Escherichia coli, Lactobacillus and Bifidobacterium in 1g of cecal contents was detected, and compared the inhibitory on the three microbes of lysozyme and the other three feed additives.Antibacterial tests showed that lysozyme in 200mg/kg has a inhibition zone with a diameter of 18mm, had a significant inhibitory effect and can be used as a feed additive with the concentration. Animal experiment showed: (1) lysozyme can improve ADG of duck, reduce daily feed intake and was outweigh the other three feed additives(nosiheptide, kitasamycin and chlortetracycline). Lysozyme can reduce the F/G and feed cost and outweigh nosiheptide and chlortetracycline while no significant difference compared with kitasamycin. Compared with the other three feed additives, lysozyme can improve ADG of duck and reduce daily feed intake which was outweigh the other three feed additives. Lysozyme can reduce the F/G and feed cost and outweigh nosiheptide and chlortetracycline while no significant difference compared with kitasamycin. (2)Lysozyme and the other three feed additives all had a increase trend in the index of bursa of Fabricius, while the difference was not significant (p>0.05). Lysozyme and the other three feed additives all can improved the thymus index while lysozyme was the best and had a significant difference compared with control (0.01< p <0.05). Lysozyme and the other three feed additives all can improve index of spleen, lysozyme and kitasamycin had significant difference (0.01 0.05). Compared with the control group, lysozyme and nosiheptide, kitasamycin, chlortetracycline have significant effect on inhibition of Escherichia coli(0.01 |
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