Effect Of Chitooligosaccharide On The Growth Performance, Carcass Traits, Immunologic Function And Bone Parameters Of Broiler Chickens

Effects of chitooligosaccharide(COS) on the growth performance, carcass traits, immunologic function and bone parameters of broiler chickens were studied in our research. A total of one hundred fifty male AA broiler chickens(1 d) were randomly allocated to 5 treatments, 6 replicates in each treatment and each replicate of 5 broilers. Different levels of Ca and COS were designed in our study(Control group: basal diet + 0 mg/kg COS;Treatment 1: basal diet + 150 mg/kg COS;Treatment 2:basal diet + 300 mg/kg COS; Treatment 3: low-calcium diet + 0 mg/kg COS;Treatment 4: low-calcium diet + 300 mg/kg COS.). The experimental phase included the starter(1-21 d)and grower phases(22-42 d). Results:1. Growth performance Adding amount of 300 mg/kg COS significantly increased body weight gain of 1-42 d and feed intake of 1-21 d and 1-42 d(P<0.05);Compared with the broilers of the control group, feed intake and body weight gain of treatment 1( basal diet + 150 mg/kg COS) at each stage were enhanced in some degree but not reaching significant level(P>0.05); Feed conversion ratio of each stage among groups showed no significant difference(P>0.05) while 1-21 d feed conversion ratio in Treatment 4(low-calcium diet + 300 mg/kg COS)was reduced by 9.812% compared with the Treatment 3(P>0.05).2. Carcass traits Comparing with the control group, 42 d live body weight was eveluated significantly in broilers fed treatment 2 and treatment 4 diet(P<0.05). Broilers fed basal diet with 150 mg/kg COS had better percentage of 42 d breast muscle yield(P<0.05) but lower thymus weight of 21 d(P<0.05) than those fed basal diet without COS. The other carcass traits of 42 d broiler chickens showed no significant difference(P>0.05).3. Serum biochemical indexes No difference was found for total cholesterol(CH), triglyceride(TG), glucose(GLU), high-density lipoprotein(HDL), low density lipoprotein(LDL), HDL/LDL and Ca among basal diet groups and low-calcium diet groups(P>0.05). Comparing with control group,the content of 21 d serum P of treatment 2(basal diet + 300 mg/kg COS) was increased by 80.876%(P<0.05).4. Immunologic function and intestinal structure Basal diet supplementiation of 150 mg/kg COS lowed the weight and index of thymus of 21 d broiler chickens when compared with the control group and treatment 2. The ratio of CD4 / CD8 of treatment 1( basal diet + 150 mg/kg COS) was 2.032 times of that in control group(P<0.05). Broilers fed low calcium diet with 300 mg/kg COS achieved better thymus index and duodenum villus height of 21 d which were 153.026%(P<0.05) and 184.466%(P<0.05) of that in treatment 3(P<0.05), while spleen index and thymus index of 42 d were lowered(P<0.05).5. Bone parameters Comparing with the control group, the calcium contents in tibia of 21 d, tibia length of 42 d, weight and length of 42 d femora of treatment 2( basal diet + 300 mg/kg COS) were increased by 29.536%(P<0.05), 6.079%(P<0.05), 29.790%(P<0.05) and 7.598%(P<0.05), respectively, but the other bone parameters between basal diet groups showed no significant difference(P>0.05). The calcium contents in tibia(21 d) and ash content in femora(42 d) of Treatment 4(Low-calcium diet + 300 mg/kg COS) were reduced by 33.139%(P<0.05) and 3.890%(P<0.05) while better results of the weight and length of tibia and femora length of 42 d were achieved(P<0.05) when compared with Treatment 3.Conclusions Broilers fed basal diet with 300 mg/kg COS obtained the best growthpromoting effect and bone parameters while for lymphocyte parameters, the optimal dosage is 150 mg/kg. Ading COS in low calcium diet could achieve better growth performance, villus height of duodenum, bone parameters and development of immune organs of 1-21 d broilers.