| Summary: | 碩士 === 國立臺灣大學 === 動物科學技術學研究所 === 100 === Chitooligosaccharide (COS) is obtained by chemical and enzymatic hydrolysis of chitosan. COS has not only the same biological functions as chitosan, but also has lower viscosity and higher water solubility than chitosan. Furthermore, COS supplementation had been confirmed that could enhances the performance and apparent digestibility of broiler. Due to environmental pollution and cost, it is better to produce COS by enzymatic than chemical method. Several Bacillus spp., including B. licheniformis, have chitosanase activity. Thus, this study was conducted to investigate the effect of supplementation of B. licheniformis CK1 and its chitosan fermentation broth (CFB) on growth performance of broilers.
First of all, the growth and chitosanase activity of B. licheniformis CK1 cultured in medium containing 1% chitosan, 1% tryptone, and 1% sodium chloride were determined. B. licheniformis CK1 attained to maximum bacterial counts after 24 hours of incubation (108 CFU/mL) and had highest chitosanase activity after 12 hours of incubation (4.7 U/mL).
Then, for the animal trial, 0-day-old Arbor Acres broilers were randomly assigned into four groups, including control group, CK1 group (supplementation of B. licheniformis CK1 in a concentration of 108 CFU/kg), CK1+CFB group (supplementation of CFB with B. licheniformis CK1 in a concentration of 108 CFU/kg), and COS group. There were four replicates of 10 broilers within each group. In the first trial, the results showed that B. licheniformis CK1 and its fermented chitosan broth supplementation significantly decreased feed intake (FI) but increased feed conversion ratio (FCR), and had no adverse effects on the organ, as well as blood characteristics. In the second trial, the results of FCR of the broilers in the CK1+CFB group during 4-6 wk and during 0-6 wk were the same as those in first trail. Compared with the control group, serum immunoglobulin G levels of broilers in the other treatment groups were slightly higher during 0-6 wk. Moreover, the broilers in the CK1+CFB group and COS group showed a slight increase of Lactobacillus counts and decrease of Escherichia coli counts in the gut microflora during 0-3 wk. The villi of broilers in the CK1 group and the CK1+CFB group were more complete, compact and higher than those in the control group or commercial chitooligosaccharides group.
In summary, supplementation of B. licheniformis CK1 and its chitosan fermentation broth in broiler feed improved FCR and might possess better nutrient states. Besides, both of them perhaps could modulate immunity in broiler. These findings revealed that B. licheniformis CK1 and COS have potential for use as feed supplementations to broilers.
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