| The deep-litter system breeding technology has been promoted in many provinces in order to solve the severe pollution problems caused by manure of livestock. The deep-litter system breeding model is a breeding technology based on the use of natural or artificial microorganisms to reduce animal fecal contamination and improve animal housing environment. As the deep-litter system breeding technique has been widely applied, people paid more and more attention on health and safety of litter in the operational procedure.In this study, we investigated the changes of quantity and diversity of microorganism in the deep-litter system chicken breeding model using litter and the effects of deep-litter system with different years on chicken serum immunity indexes. And we also tested the levels of nitrite, heavy metals (lead, cadmium) and mycotoxins (total aflatoxin, zearalenone, deoxynivalenol, T-2toxin, ochratoxintoxins, fumonisin) in chicken and litter with different years. The results were as follows:1. When using the deep-litter system, we found that the populations of most microorganism in litter declined over time, but there were differences in the pace of decline among different types of microorganism. Probiotic bacteria (Bacillus, Lactobacillus) were stable as the dominant bacteria, lactic acid bacteria was first increased and then decreased, bacillus has been decreasing year by year. The amounts of harmful bacteria (Salmonella bacteria, Escherichia coli, mold) have dramatically decreased.2. The DGGE fingerprinting profiles showed that diversity of flora in the surface layer, intermediate layer and the bottom of litter has been declining over time. The average number of bands in the first-year, second-year and third-year deep-litter system decreased from39.9to21.3.3. Compared to the control group (common concrete surface), the levels of total protein, globin and globulin ratio in chicken blood serum in deep-litter system with different years improved, but there was no significant difference (P>0.05). Albumin concentration in the control group was significantly lower than the three-year experimental group (P<0.05). Immunoglobulin (IgA, IgM, IgG) concentration in chicken serum was higher than that of the control group. IgG concentration of1,2and3-year deep-litter system were47.59%,60.1%and43.39%higher than that of the control group, respectively, showing a significant difference (P<0.05). The amounts of IgA in2-year and3-year deep-litter system group were24.00%,17.59%more than that in the control group, showing a significant difference (P<0.05). IgM content in2-year deep-litter system group were42.86%more than that in control group and25.00%more than that in1-year deep-litter system group (P<0.05). As can be seen, non-specific immune system has been induced for the reason that chicken activity levels have been increased by different raising patten (fermentation bed) and chicken liked to peck at the litter for microorganisms.4. Lead, cadmium in deep-litter system with different years accumulated as time went on. The detected values in litter and chicken were within the limitation of national standards. The result indicated that the concentrations of lead, chrome and other heavy metals in deep-litter system confirmed to national security requirements during the whole service life.5. The detection values of mycotoxin (total aflatoxin, T-2toxin, deoxynivalenol, zearalenone, ochratoxin, fumonisin) in litter and chicken were lower than the detection limit, confirming to the national standards. The results showed that if we strictly control the factors that easily resulted in mold growth such as humidity, temperature, service life of the fermentation bed for breeding chicken, the concentration of mycotoxin will be remained within the limited scope of national standards. It could also ensure the quality of chicken and growth performance of chickens, consistent with the food safety requirements.6. The contents of nitrite in1,2,3-year deep-litter system and chicken were significantly increased (P<0.05), indicating that nitrite accumulated in the deep-litter system and chicken. But all of the sample detection values met the national standards. Using different years of deep-litter system reared chicken nitrite content of the safety and quality of agricultural products pollution-free livestock and poultry meat safety requirements, Fermentation bed for chickens mode met the food safety requirements as the nitrite level of chicken in deep-litter systems with different years confirmed with the safety standards of Pollution-Free Livestock Productions. |
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