Effects Of Recombinant Lysozyme On Growth Performance And Immune Function In Broilers

The objective of this experiment was to investigate the effects of recombinant lysozyme on the growth performance,nutrient substance metabolism,structure of intestine mucosa,and immune function of broilers, and finally to discuss the possibility to displace the antibiotics and to determine the optimal concentration. The broilers were divided randomly into 5 groups,of which,3 groups for 0.1%,0.2%,and 0.3%of lysozyme respectively,one group for antibiotic and one group for control.The results were showed as follows:Experiment 1.Four hundred and fifty AA chickens at age of 1 day were divided randomly into five groups.The experiment lasted for 42 days,and finally the broilers were abataged to study the effects of recombinant lysozyme on the growth performance and quality of naked body.The results showed that,from 1 to 21 days,the ADG of 0.1%group was significantly higher than other four groups(P<0.05),but no obvious differences were observed among the other four groups.There were obvious differences in the ratio of feed to gains between 0.1%group and other three(P<0.05),but no obvious differences were observed with flavomycin group(P>0.05).From 22 to 42 days,there were no obvious differences in growth among the five groups(P>0.05).The ratios of feed to gains in 0.3%groups and flavomycin group were significantly higher than other three groups(P<0.05).Experiment 2.Sixty broilers were divided randomly into five groups to study the effects of recombinant lysozyme on nutrient substance metabolism.The results showed that,the metabolizable energy was the highest when flavomycin was added in the diet.Compared with that of the control group,both flavomycin group and 0.2%group improved the metabolizable energy by 9.38%and 7.64%,respectively,while all the lysozyme groups had no significant differences(P>0.05).While that of the metabolizable energy,CP and EE were not significantly different from control group(P>0.05),when 0.2%recombinant lysozyme was added in the diet.The lenth of intestinal villi of 0.2%group were higher significantly,compared with the control group at the day of 21 and 42,and also the ratio of the lenth of intestinal villi and the depth of cryptae of the day of 42. The lenth of duodenum intestinal villi of flavomycin group were higher significantly,compared with the control group at the day of 21 and 42(P<0.05),and also the ratio of the lenth of intestinal villi and the depth of cryptae of the day of 42.The effects of 0.3%group were the same as the flavomycin group.Experiment 3.Compared with control group,the relative weights of bursas of Fabricius and spleens of experimental groups increased significantly in 3 week(P<0.05),and 0.2%group had the best effects,but the relative weight of thymuses were decreased in recombinant lysozyme groups.The diet added recombinant lysozyme could promote T lymphocyte transformation,that meant the recombinant lysozyme could improve the specific immunity.The level of IgA of the 0.2%group was significantly higher than that of other groups (P<0.05),and the 0.3%group enhanced level of IgM(P>0.05),that meant the recombinant lysozyme could increase the contents of immunoglobulins.