Study On The Effect And Mechanism Of Lysozyme Fed To Broilers

This research aimed to study the effect and the mechanism of lysozyme fed to broilers. The micro-organism counts of fresh digesta are analyzed as index, and the response of relative mRNA expression of splenic cytokine, IGF-1 and the performance to lysozyme and antibiotics are also involved in this study. The experiment consist of 4 groups in which the broilers were fed basal diets, basal diets with antibiotics and basal diets with different dosages of lysozyme respectively, all broilers had unrestricted access to experimental diets and water throughout the experiment. The results showed that:(1) the fresh digesta from the treated group had less micro-organism counts such as the Clostridium and Coliforms than control group. Villous height of the broilers fed with lysozyme and antibiotics become higher than the control group and the crypt depth becomen deeper, which mean that the lysozyme could improve the intestinal health of broilers under the experimental situation. The lysozyme and antibiotic also decrease the plasma concentrations of ammonia in broiler in 42nd day(P<0.01).(2) the lysozyme and antibiotic low the indices of immune organ and serumal antibody titer of New castle disease of broilers, the diets supplemented with 300g/T lysozyme decreased significantly the splenic relative expression of IL-1βof 42d-day-old broilers(P<0.01).The splenic relative expression of TNF-αmRNA levels were not effected by the lysozyme and antibiotics in this experiment.(3) the diets with 150g/T and 300 g/T lysozyme could increase the IGF-1 mRNA levels in liver 12.5% and 10.4% respectively, but show no difference compared with the control group(P>0.05). Different treatment did not effect the IGF-1 mRNA levels in the pectoral muscle of 42d-old broilers(P>0.05).(4) the lysozyme and antibiotic did not affect the apparent digestibility of different nutrient in 42d-old broilers(P>0.05), the same as the ADFI(P>0.05), but the lysozyme improve the ADG and low the F/G during the 42d experiment. Compared with the chicks fed antibiotics, the chicks fed lysozyme did not show significant differences in terms of final performance (P>0.05).Generally, the results from the experiment demonstrated a potential of lysozyme to be used as a substitute for antibiotics in broiler diets.