| The results of this experiment were to evaluate the performance of AA broilers by different doses effects of human lysozyme expressed by Pichia pastoris by feeding test,the effects of microbial flora,serum biochemical indices and immune function of intestinal microflora were the basis for the expression of the suitable dosage instead of antibiotics in broiler diets.720 AA healthy broiler chickens of 1 day old were random Ly divided into 6 treatment groups on the basis of similar weight.Each group was divided into 6 replicates with 20 duplicates each,male and female were mixed.The blank control group was fed corn-soybean meal basal diet,The antibiotic group added 72 mg / kg Salinomycin + 4 mg / kg Flavomycin to the basal diet.Groups I,II,III and IV were supplemented with 2.0,4.0,6.0 and 8.0 g / kg human lysozyme expressed by Pichia pastoris(4702U/g).The test period is 42 days.one male or female be random Ly selected from each repeat to make metabolic test about chicken for a period of 4 days at 35 days of age.Experiment 1:The effects of human lysozyme expressed by Pichia pastoris on the growth performance and slaughter rate of broiler were studied.The results showed as follows: 1)During the 1-21 days of age,there was no significant difference between group ?,group ?,group ?,group ?,antibiotic group and control group at weight,mortality,ADG,ADFI and F/G(P > 0.05).At 42 days of age,the body weight and ADG of groups ?,? and ? was significantly higher than that of control group(P<0.05),but there was no significant difference between group ?,?,?,? and antibiotic group(P>0.05).The F/G of control group was significantly lower than that in group ?,group ?,group ? and antibiotic group(P<0.05),group ? was the best.During the 1-42 days of age.The ADG of control group was significantly lower than group II,group III,group IV(P<0.05).There was no significant difference in each group compared with antibiotic group.The F/G of control group was significantly higher than group II,group III,group IV(P<0.05).There was no significant difference in mortality and ADFI among treatment groups.2)There was no significant difference in slaughter rate and leg muscle rate among treatment groups(P>0.05).The halfeviscerated rate of the antibiotic group and human lysozyme expressed by Pichia pastoris was significantly higher than that of the control group(P<0.05).The rate of pectoralis muscle in group ? was significantly higher than that in control group(P < 0.05).And the rate of breast muscle in group ?was significantly higher than that in group?,?and?(P<0.05).Therefore,the human lysozyme expressed by Pichia pastoris can improve the weight of broiler chickens and reduce the weight ratio,improve the quality of the carcass,to promote growth,and the effect of antibiotic group is more consistent,it is proved that it can be directly added to feed to replace antibiotics,to add 4.0g/kg human lysozyme expressed by Pichia pastoris on the growth of broiler chickens.Experiment 2:This experiment mainly discussed the effects of human lysozyme expressed by Pichia pastoris compared with antibiotics on digestibility of broilers and intestinal microflora.The results showed as follows:1)The digestibility of CP,EE,CA and TP in broilers was not significantly different from that of the control group(p>0.05)after the human lysozyme expressed by Pichia pastoris with antibiotics or different additive amounts.2)Group ?,? decreased the number of escherichia coli in jejunum and cecum(P < 0.05).The human lysozyme expressed by Pichia pastoris in different dosage groups can significantly reduce the number of Clostridium difficile(P<0.05),and there was no significant difference compared with antibiotic group(P>0.05).The results showed that the human lysozyme expressed by Pichia pastoris in different doses of Pichia pastoris had no significant effect on the number of Lactobacillus and Bifidobacterium in Jejunum and cecum of Broilers(p>0.05).Adding the appropriate amount of human lysozyme expressed by Pichia pastoris could improve the utilization rate of dietary nutrients of broilers.Significant reduction in the number of harmful microorganisms such as Escherichia coli and Clostridium in the intestine.Had no effect on beneficial bacteria such as Lactobacillus and Bifidobacterium in the intestine.The addition of 4.0 g / kg and 6.0 g / kg had better effect than other dosage groups.Experiment 3:This experiment mainly discussed the effects of human lysozyme expressed by Pichia pastoris on serum biochemical indexes and immune function of broilers compared with antibiotics.Test results show that:1)There was no significant effect on immune organ index of broilers in antibiotic group and human lysozyme test group(P>0.05).Antibiotics and human lysozyme expressed by Pichia pastoris test showed a trend of increasing the thymus index of the broilers than that of the control group(P=0.066).Among them,the experimental group III had the best effect on raising the thymus index of the broilers,followed by the test group II,the test group IV,the antibiotic group respectively increased by 5.84%,4.38%,4.38%,2.95%.Compared with the control group,each treatment group had a trend of increasing the bursa index of 42-day-old broilers(P=0.073),group?and group?were better.The descending order was that of antibiotic group,group I,group IV,which were respectively increased by 17.39%?17.39%?14.49%?7.25%?7.25%.2)the content of serum lysozyme in broilers was significantly increased by the treatment of human lysozyme expressed by Pichia pastoris than that of the control group(P<0.05).The effect of experimental group ? was the best and 12.91% higher than that of the control group.3)3 There were no significant differences in WBC number,RBC quantity and Plt quantity in each treatment group(P>0.05),indicating that the human lysozyme expressed by Pichia pastoris could maintain the health level of the organism to some extent.4)The levels of ALT in serum of antibiotic group and group ?,?,? were significantly lower than those of control group(P <0.05).There was no significant difference in serum ALT content between antibiotic group and human lysozyme expressed by Pichia pastoris fermentation products group(P> 0.05).Compared with control group,antibiotic group,group ? and ? significantly reduced serum AST content in broilers(P<0.05).There was no significant difference between group ?,? and serum AST of broilers(P> 0.05).GLU levels of Serum in antibiotic group,group ? and group ? were significantly lower than those in control group and group?(P<0.05).Serum GLU of group ? and group ? has no significant difference than that of antibiotic group(P> 0.05).Cholesterol is the main lipid in the serum,and its content in the serum affects the health of the body.Compared with control group,antibiotic group,group ?,?,? and ? can reduce serum CHOL content to some extent.It shows that effects of human lysozyme expressed by Pichia pastoris can regulate cholesterol metabolism.Therefore,effects of human lysozyme expressed by Pichia pastoris can promote the development of immune organs to some extent.Serum lysozyme in serum were Enhanced.Improve liver function of broilers,promoting the transfor mation and utilization of GLU,regulating cholesterol metabolism,thus enhancing the immune and metabolic functions of the body.it beneficial to gain weight.The human lysozyme expressed by Pichia pastoris can be used as a substitute for antibiotics in the diet of broilers,addition of 4g / kg and 6g / kg is best. |
PDF Full Text Request