Construction And Application Evaluation Of A Probiotic Agent For Deodorant Emission Reduction For Pig

Pig farming harbors the dominant status in Chinese livestock industry.However,the continuous intensification and expansion of farming scale led to diverse environmental contamination issues,especially the malodorous gases.Odor gas could seriously endanger both physical and mental health of residents,which is the most important pollutant during environmental management.Current odor gas control methods relied on endpoint remediation,while the routes for reduction of source emission remained absent.Therefore,this study aimed to establish a feeding microbial agent with both odor abatement and probiotic effects.The performance of this agent was assessed by intestinal simulation test before practical application in large-scale hoggery,then a comprehensive evaluation including odor abatement effect,growth performance,and pork quality indices were performed to determine the effect of the microbial agent.Meanwhile,the regulation effect of feeding agent on the intestinal flora of pigs was by high-throughout sequencing.Finally,a specialized microbial feeding agent was developed,as well as the corresponding production and operation instructions,which could be beneficial to reduce odor during pig farming and support the sustainable development of Chinese intensive hog breeding industry,resulting in reassurance of food and environmental safety.The main research results are as follow.1.To obtain microbes with intestinal probiotic and odor abatement properties,specific medium cultivation,digestive resistance characteristics,and other methods were used isolate and screen a variety of probiotic strains.These candidate strains should be within the directory promulgated by MOA,which restricted the classification of microbes allowed in breeding industry.After comprehensive analyses,including molecular biology identification,physiological and biochemical identification,and microscopic morphological observation,the suitable strains for microbial agent formulation were identified as Bacillus subtilis KC4,B.licheniformis SY3,Enterococcus faecalis DS4-3 and Saccharomyces cerevisiae 1421.2.To evaluate the effect of different strain combinations on odor reduction of pig intestinal contents,strain antagonism experiments and in vitro intestinal simulation tests were performed.The final composition of the microbial agent was formulated as"0.075%B.subtilis KC4+0.075%B.licheniformis SY3+0.075%S.cerevisiae 1421+0.075%E.faecalis DS4-3".Compared with control group,the optimized bacterial agent showed a 24.92%reduction of NH₄⁺-N ratio,36.12%reduction of S^2--S ratio,and a 55.86%reduction of VFAs content during intestinal simulation experiment.3.In order to evaluate the capacity of“odor abatement-probiotics”agent in hoggery,animal feeding experiments were conducted with 16 piglets weighing about12.5 kg.The results showed that compared with control group,the average daily weight gain of piglets in probiotic agent group increased by 19.57%,the average feed consumption weight gain ratio decreased by 15.22%,and the eye muscle area significantly increased by 26.87%.The pork yellowness value was b*,while and the fat content in probiotic agent group was significantly reduced.The NH₃concentration in the pens of the probiotic-fed group was maintained at a relatively stable and low level,which concentration was 5-10 ppm during the trial period from day 4 to 45.However,the OU value was more fluctuant,but remained significantly lower than the control group for most days of the feeding period.4.In order to investigate the effective site and influence of the“odor abatement-probiotic microbial”agent in pig gut,the microbial community of the fresh contents of pig intestines at different locations after feeding probiotic agent was analyzed by16S and ITS amplicon sequencing.It was found that the effective site of the probiotic agent was mainly in the ileal section of the digestive tract.The abundance of odor-emission bacterium Clostridium＿sensu＿stricto＿1 was significantly reduced from6.03%to 0.62%,and the abundance of Lactobacillus spp.,which were beneficial to the intestine,was significantly increased from 0.61%to 7.11%in probiotic agent group compared with the control group,while the effect on the core dominant microbial flora was not significant.The directional regulation of feeding agent exhibited odor abatement and probiotic properties without breaking the balance of gut microbes,resulting in the gut stability and animal health.