Production of odors is a complex process. Many bacterial species are involved in the production of an extensive array of key odor compounds in stored pig slurry. Understanding of basic microbial communities and their role during storage periods is an essential way to control and prevent the odors generations. In this aspect, the pig slurry samples were taken directly from deep pits of finisher pig building every two weeks, their biochemical changes were analysed, and the indigenous bacterial communities that involve in offensive odor producing compounds were identified. The SCFA, BCFA, phenols, and indoles levels altered drastically in the slurry during storage periods. The COD, BOD, SS, P2O5, TKN, and NH4-N were increased in the stored slurry. Bacterial ecology indicates Firmicutes and Bacteroidetes phyla were dominantly found in pig slurry. Odorants produced in pig slurry were correlated with bacterial communities. Phenols, indoles, SCFA, and BCFA productions were positively correlated with bacteria species which comes under phyla of Firmicutes and Bacteroidetes. It seems that bacterial species under Firmicutes and Bacteroidetes phyla play an important role in the offensive odor compounds production. Taken together, the prevention of these phyla bacterial growth and early discharge of pig slurry might reduce the offensive odor production.

Traditionally slurry is used as source of nitrogen, phosphorous, and potassium in bio fertilizers to improve crop production. However, poorly managed slurry causes a hazardous effect to the environment by producing greenhouse gases, causing the eutrophication of water bodies, and polluting the groundwater. It has been largely reported that the microbial presence in slurry causing a diverse effect on its storage and disposal system. However, the diversity of bacterial populations in pig slurries remains largely unexplored. Here we report the bacterial diversity present in the slurry from slurry pits, and the effect of storage time on bacterial population. We collected 42 samples from three different pig slurry pits, as three replicates from each one until the 14th week. We used the 16S rRNA, Quantitative Insights Into Microbial Ecology (QIIME) and Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) protocols for the metagenomic downstream analysis. Taxonomic annotation using the Greengenes metagenomic database indicated that on an average 76.2% Firmicutes, 14.4% Bacteroidetes, 4.9% Proteobacteria, etc. microbial populations were present. Comparative microbial analysis showed that the population of Firmicutes decreased from the first to the 14th week, whereas the population of Bacteroidetes increased from the first to the 14th week. Through principal coordinate analysis (PCoA), (linear discriminant analysis effect size (LEfSe), and Pearson’s correlation analysis, we found microbial biomarkers according to the storage time point. All bacterial populations were well clustered according to the early, middle, and last weeks of storage. LEfSe showed that Actinobacteria, Lachnospiraceae, Ruminococcaceae, and Bacteroidia are dominantly present in first, seventh, ninth, and 14th week, respectively. Lachnospiraceae and Ruminococcaceae are ubiquitous gastrointestinal non-pathogenic bacteria. KEGG pathways, such as membrane transport, carbohydrate and amino acid metabolism, genetic replication and repair, were significant among all samples. Such a KEGG pathway may indicate the association between the host organism’s metabolic activity and the microbes present in the gastro intestinal tract (GIT).

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In this study, we aimed to determine the ammonia emission characteristics through analysis of ammonia concentration, ventilation rate, temperature, and relative humidity pattern in a mechanically ventilated swine finishing facility in Korea. Three pig rooms with similar environmental conditions were selected for repeated experimentation (Rooms A–C). Ammonia concentrations were measured using a photoacoustic gas monitor, and ventilation volume was estimated by applying the least error statistical model to supplement the missing data after measurement at several operation rates using a wind tunnel-based method. The mean ammonia concentrations were 4.19 ppm, and the ventilation rates were 24.9 m3 h−1 pig−1. Ammonia emissions were calculated within the range of 0.40–5.01, 0.25–4.16, and 0.37–5.68 g d−1 pig−1 for Room A, Room B, and Room C, respectively. Ammonia concentration and ventilation rate showed a weak negative correlation (r = −0.13). Ammonia emissions were more markedly affected by ammonia concentration (r = 0.88) than ventilation rate (r = 0.31). This indicates that ammonia concentration reduction can be effective in reducing ammonia emissions. The mean daily ammonia emissions, which increased exponentially over the finishing periods, were calculated as 1.78, 1.57, and 1.70 g d−1 pig−1 for Room A, Room B, and Room C, respectively (average 1.68 g d−1 pig−1).