| Traditional patterns of livestock and poultry industry often causes severe water,soil and air pollution,while the technology of litter bedding system(LBS)as one of the important measures can effectively reduce the environmental pollution from the source.At present,the fermentation bed breeding mode is still in the exploratory stage in Pekin duck.The study explored the application of functional bacteria into LBS to solve the problem of pollution on the Pekin duck farms and improve the indoor air environment.And the process of manure digestion in fermentation bed was simulated to investigate the fates of environmental indicators and reveal the mechanism of LBS.It would be helpful to provide theoretical support for the ecological culture of Pekin duck.Bacterial strains were screened with the function of ammonia-reducing and acid-producing.The 3 strains,YFFJ-2,NJ-6 and acid56 with high efficiency were then obtained and identified as Bacillus subtilis,B.licheniformis and B.megaterium.The mixed bacterial agent of the 3 strains(in 2:2:1 ratio)was incubated into the piled padding for the fermentation process.Results showed that the temperature reached up to 65℃ in 12 h at the depth of 10 cm of the stacking,and the maximum temperature was 70.70C during the fermentation process,with the pH of 7.25～7.61.The main cultured bacterium was B.subtilis which covered 85.23%of the total culturable bacteria.Then,the fermented litter was put into the Pekin duck house to conduct the fermented litter bed system(FBS)test.It was found that there was no malodor in the duck house.Moreover,with this system,the number of mold was reduced by 12.34%and 38.68%in the air and in the litter,respectively,and the ammonia was decreased by 14.60%compared with the control.The manure-in-litter-bed digestion process was simulated in laboratory,to explore the effect of the bacterial agents and pre-fermentation of litter on FBS.NH3 and GHG emission rate,the genes(amoA and hao)related with the nitrogen cycle were systematically determined and analyzed.The results showed that the relative high pH environment caused by manure could promote the release rate of CO2 and NH3,while inhibit that of N2O in the start stage of the digestion.In the middle stage of digestion,the emission rate of N2O reached the maximum and was positively correlated with pH.The increase of amoA and hao copies was in good relation with the increased release rate of N2O and decreased release rate of NH3 at the same fermentation degree of manure.The release rate of CH4 kept very low in all treatments.With high throughput sequencing technology,the diversity and abundance of bacterial communities and their interaction with gas emissions were studied during the whole digestion process.The results showed that the bacterial community diversity in the pre-fermented litter was richest due to the Shannon index was significantly higher than any other control.After analyzing the relative abundance of species in different stages,Deinococci was proved to be the main bacteria related to CO2 and NH3 emission,and Flavobacteriia and Thermomicrobia were the main communities responsible to N2O emissions,while the increase of relative abundance of Bacilli and Actinobacteria was beneficial to reduce N2O release rate.With the bacterial agent applied in the FBS,the addition of Bacillus into the litter increased the relative abundance of Bacilli,and reduced the emission of N2O.The bacterial community was analyzed in the litter that had been used for for 9 months.It was found that Gammaproteobacteria,Alphaproteobacteria,Sphingobacteriia,Flavobacteriia were the dominant bacterial community,among of which the main bacteria included B.sonorensis,B.subtilis,B.methylotrophicus,Arthrobacter nicotianae,B.megaterium.The relative abundance of 3 kinds of microbial inoculum kept stable as long as 3 months since the FBS was started.The decomposition ability of the litter in FBS retarded after working for 9 months base on NMR analysis.The products composted by the used bedding materials met the standard of bioorganic fertilizer.In this study,application of the FBS solved the problem of manure and effluent pollution in the duck farm,achieved zero emission and improved the indoor air environment.The ecological breeding technology of FBS showed the value of further research and popularization in the future. |
