Effects Of Chito-Oligosaccharides With Different Molecular Weights On Growth,Antioxidant And Immune Function Of Yellow-Feathered Broilers

Chito-oligosaccharides(COS)is a kind of natural oligosaccharides,which have antioxidant,antibacterial,immune and lipid metabolism regulation effects.This experiment was conducted to investigate the effects of COS on growth performance,antioxidant status and immune function of yellow-feathered(the fast-growing)broilers in terms of growth performance,tissue antioxidant status,immune organ development,serum biochemical indices and expression of related transcription factors.Using the single-factor completely random design method.A total of 240one-day-old yellow-feathered broiler hens(body weight 35.30±0.08g)were randomly divided into 4 groups with 6 replicates per group and 10 hens per replicate,which were control group and supplemented with 2400,4800 and 9600 Da COS(0.58%),respectively.The experiment lasted for 56 days.The results show that:(1)Supplementation of COS with different molecular weights had no significant effects on ADFI,F/G and mortality rate of broilers(P>0.05);However,adding 2400 Da COS tended to increase the final weight(P=0.094)and the whole ADG(P=0.092)of yellow-feathered broilers.(2)Compared with the control group,2400 Da COS significantly increased serum CAT activity(P<0.05).(3)Different molecular weight COS had effects on SOD,GSH-Px and CAT activities and MDA content in liver(P<0.05): The SOD activity in liver in 2400 Da COS group was significantly higher than that in control group and 4800 and 9600 Da COS groups(P<0.01),and the SOD activity in 4800 and 9600 Da groups was significantly lower than that in control group(P<0.01).GSH-Px activity and CAT activity in 2400 Da group were significantly higher than those in 4800 and 9600 Da COS groups(P<0.01).MDA content in 2400 Da group was significantly lower than that in control group(P<0.05),and 2400 Da COS had better antioxidant effect on liver of yellow-feathered broilers.(4)Different molecular weight COS affected the enzyme activities of GSH-Px and CAT and the content of MDA in breast muscle(P<0.05): the activity of GSH-Px in 4800 Da COS group was significantly higher than that in control group(P<0.01).CAT activity in COS group was significantly higher than that in control group(P<0.01),and MDA content in 2400 Da COS group was significantly lower than that in control group(P<0.05).(5)Different molecular weights of COS affected thymus index of yellow-feathered broilers(P<0.05).The thymus index of yellow-feathered broilers in2400 Da COS group was significantly higher than in control group(P<0.05).There was no significant difference in indexes of other immune organs among groups(P>0.05).(6)Different molecular weight COS had no effect on serum Ig G of yellow-feathered broilers,but 2400 Da COS group had a tendency to increase serum Ig G of broilers(P=0.068).(7)Different molecular weight COS affect the expression of GPx4 in liver of yellow-feathered broilers(P<0.05).GPx4 expression in the 2400 Da COS group was significantly higher than that in the other two COS groups.Different molecular weight COS tended to decrease NF-κB expression in liver of yellow-feathered broilers(P=0.075).(8)Different molecular weight COS also had certain effects on slaughter performance and meat quality of yellow-feathered broilers.The 4800 Da COS significantly increased breast muscle percentage and decreased abdominal fat percentage(P<0.05);In 2400 Da COS group,the dripping loss of breast muscle was decreased(P=0.067),and the content of inosinic acid in breast muscle was significantly increased(P<0.01).In conclusion,the dietary supplementation of different molecular(2400,4800 and 9600 Da)COS(0.58%)in diets had significant effects on growth,antioxidant ability and immune function of yellow-feathered broilers.The 2400 Da COS feeding had higher effects on improving growth,antioxidant ability and immune function for the indigenous yellow-feathered broiler in terms of the increased antioxidant enzyme activities,the decreased oxidized metabolites in liver and muscle,the improved thymus development and immune protein content as compared to COS with molecular weight of 4800 and 9600 Da.