Evaluation of the microbiome composition in particulate matter inside and outside of pig houses

Can environmental nebulization of lavender essential oil (L. angustifolia) improve welfare and modulate nasal microbiota of growing pigs?

The use of phytoextracts has been proposed as a method to improve animal welfare, also in pigs, by reducing stress and anxiety and improving performances. Lavandula angustifolia (Miller) essential oil (LaEO) is an interesting calming phytoextract that could be administered by inhalation for prolonged periods of time to help pigs coping with on-farm conditions. The aim of this study was to assess the effects of daily inhalation of vaporized LaEO on pigs' welfare and health indicators, and nasal microbiota, trying to understand whether this phytoextract represents a feasible tool to improve animal welfare under intensive farming conditions. Eighty-four crossbred barrows were randomly divided into 3 experimental groups: control (C); lavender (L): 3 vaporization sessions of 10 min each of a custom made 1% solution of LaEO; sham (S): same vaporization sessions of L group but only using the solution vehicle. Experimental readouts included growth parameters, behavioural traits, tail and skin lesions, hair steroids and nasal microbiota. L group animals did not show altered growth performance and seemed calmer (increased recumbency time), with decreased amount of skin lesions also associated with lower severity class for tail lesions. They also showed decreased CORT/DHEA ratio, potentially suggesting a beneficial effect of LaEO. Inhalation of LaEO significantly affected the nasal pig microbiome by reducing its diversity. Overall, the study suggests how inhalation of Lavender essential oil may be capable of improving welfare in growing pigs, yet it is pivotal to consider the microbial modulatory capabilities of essential oils before exploiting them on larger scale.

Genomic characterisation of bioaerosols within livestock facilities: A systematic review

Livestock facilities are widely regarded as reservoirs of infectious disease, owing to their abundance in particulate matter (PM) and microbial bioaerosols. Over the past decade, bioaerosol studies have increasingly utilised high throughput sequencing (HTS) to achieve superior throughput, taxonomic resolution, and the detection of unculturable organisms. However, the prevailing focus on amplicon sequencing has limited the identification of viruses and microbial taxa at the species-level. Herein, a literature search was conducted to identify methods capable of overcoming the aforementioned limitations. Screening 1531 international publications resulted in 29 eligible for review. Metagenomics capable of providing rich insights were identified in only three instances. Notably, long-read sequencing was not utilised for metagenomics. This review also identified that sample collection methods lack a uniform approach, highlighted by the differences in sampling equipment, flow rates and durations. Further heterogeneity was introduced by the unique sampling conditions, which makes it challenging to ground new findings within the established literature. For instance, winter was associated with increased microbial abundance and antimicrobial resistance, yet less alpha diversity. Researchers implementing metagenomics into the livestock environment should consider season, the microclimate, and livestock growth stage as influential upon their findings. Considering the increasing accessibility of long-read sequencing, future research should explore its viability within a novel uniform testing protocol for bioaerosol emissions.

Effects of microbes in pig farms on occupational exposed persons and the environment

In terms of pig farming, pig gut microbes have a significant effect on farmers and the farm environment. However, it is still unclear which microbial composition is more likely to contribute to this effect. This study collected a total of 136 samples, including pigs' faeces samples, farmers' faeces samples, samples from individuals who had no contact with any type of farm animal (referred to as 'non-exposed' persons), and environmental dust samples (collected from inside and outside pig houses and the farm) from two pig farms, pig farm A and pig farm B. Whereafter, 16S rRNA sequencing and taxonomic composition analysis were performed. According to the study, compared to non-exposed persons, pig farmers had a significantly higher abundance of 7 genera. In addition, the farmers were grouped according to the duration of their occupational exposure, and it was shown that 4 genera, including Turicibacter, Terrisporobacter, and Clostridium_sensu_stricto_1, exhibited a rise in more frequent contact with pigs. As compared to outside the pig house, the environmental dust has a greater concentration of the 3 bacteria mentioned before. Therefore, these 3 microbes can be considered as co-occurring microbes that may exist both in humans and the environment. Also, the 3 co-occurring microbes are involved in the fermentation and production of short-chain fatty acids and their effectiveness decreased as distance from the farm increased. This study shows that the 3 microbes where pig farmers co-occur with the environment come from pig farms, which provides fresh ideas for preventing the spread of microbial aerosols in pig farms and reducing pollution.

Potential airborne human pathogens: A relevant inhabitant in built environments but not considered in indoor air quality standards

Potential airborne human pathogens (PAHPs) may be a relevant component of the air microbiome in built environments. Despite that PAHPs can cause infections, particularly in immunosuppressed patients at medical centers, they are scarcely considered in standards of indoor air quality (IAQ) worldwide. Here, we reviewed the current information on microbial aerosols (bacteria, fungal and viruses) and PAHPs in different types of built environments (e.g., medical center, industrial and non-industrial), including the main factors involved in their dispersion, the methodologies used in their study and their associated biological risks. Our analysis identified the human occupancy and ventilation systems as the primary sources of dispersal of microbial aerosols indoors. We also observed temperature and relative humidity as relevant physicochemical factors regulating the dispersion and viability of some PAHPs. Our analysis revealed that some PAHPs can survive and coexist in different environments while other PAHPs are limited or specific for an environment. In relation to the methodologies (conventional or molecular) the nature of PAHPs and sampling type are pivotal. In this context, indoors air-borne viruses are the less studies because their small size, environmental lability, and absence of efficient sampling techniques and universal molecular markers for their study. Finally, it is noteworthy that PAHPs are not commonly considered and included in IAQ standards worldwide, and when they are included, the total abundance is the single parameter considered and biological risks is excluded. Therefore, we propose a revision, design and establishment of public health policies, regulations and IAQ standards, considering the interactions of diverse factors, such as nature of PAHPs, human occupancy and type of built environments where they develop.

Full-length 16S rRNA gene sequencing and machine learning reveal the bacterial composition of inhalable particles from two different breeding stages in a piggery

Bacterial loading aggravates the harm of particulate matter (PM) to public health and ecological systems, especially in operations of concentrated animal production. This study aimed to explore the characteristics and influencing factors of bacterial components of inhalable particles at a piggery. The morphology and elemental composition of coarse particles (PM₁₀, aerodynamic diameter ≤ 10 µm) and fine particles (PM_2.5, aerodynamic diameter ≤ 2.5 µm) were analyzed. Full-length 16 S rRNA sequencing technology was used to identify bacterial components according to breeding stage, particle size, and diurnal rhythm. Machine learning (ML) algorithms were used to further explore the relationship between bacteria and the environment. The results showed that the morphology of particles in the piggery differed, and the morphologies of the suspected bacterial components were elliptical deposited particles. Full-length 16 S rRNA indicated that most of the airborne bacteria in the fattening and gestation houses were bacilli. The analysis of beta diversity and difference between samples showed that the relative abundance of some bacteria in PM_2.5 was significantly higher than that in PM₁₀ at the same pig house (P < 0.01). There were significant differences in the bacterial composition of inhalable particles between the fattening and gestation houses (P < 0.01). The aggregated boosted tree (ABT) model showed that PM_2.5 had a great influence on airborne bacteria among air pollutants. Fast expectation-maximization microbial source tracking (FEAST) showed that feces was a major potential source of airborne bacteria in pig houses (contribution 52.64-80.58 %). These results will provide a scientific basis for exploring the potential risks of airborne bacteria in a piggery to human and animal health.

Characteristics and Traceability Analysis of Microbial Assemblage in Fine Particulate Matter from a Pig House

Fine particulate matter (PM2.5) can carry numerous substances and penetrate deep into the respiratory tract due to its small particle size; associated harmful microorganisms are suspected to increase health risks for humans and animals. To find out the microbial compositions of PM2.5 in piggeries, their interaction and traceability, we collected PM2.5 samples from a piggery while continuously monitoring the environmental indicators. We also identified pathogenic bacteria and allergens in the samples using high-throughput sequencing technology. We analyzed the microbial differences of PM2.5 samples at different heights and during different times of day and investigated the microbial dynamics among the PM2.5 samples. To better understand the interaction between microorganisms and environmental factors among different microbial communities, we applied the network analysis method to identify the correlation among various variables. Finally, SourceTracker, a commonly used microbial traceability tool, was used to predict the source of airborne microorganisms in the pig house. We identified 14 potential pathogenic bacteria and 5 allergens from PM2.5 in the pig houses, of which Acinetobacter was the dominant bacterium in all samples (relative abundance > 1%), which warrants attention. We found that bacteria and fungi directly affected the the microbial community. The bacterial community mainly played a positive role in the microbial community. Environmental variables mainly indirectly and positively affected microbial abundance. In the SourceTracker analysis using fecal matter and feed as sources and PM2.5 sample as sink, we found that fecal matter made the greatest contribution to both bacterial and fungal components of PM2.5. Our findings provide important insights into the potential risks of pathogens in PM2.5 to human and animal health and their main sources.

The impact of different diets and genders on fecal microbiota in Hanwoo cattle

Bovine fecal microbiota is important for host health and its composition can be affected by various factors, such as diet, age, species, breed, regions, and environments. The objective of this study was to evaluate the impact of diet and gender on fecal microbiota in Korean native Hanwoo cattle. The 16S rRNA gene amplicon sequencing of fecal microbiota was conducted from 44 Hanwoo cattle divided into four groups: (1) 11 heifers fed an oat hay plus total mixed ration (TMR) diet for breeding (HOTB), (2) 11 heifers fed an early fattening TMR diet (HEFT), (3) 11 steers fed the early fattening TMR diet (SEFT), and (4) 11 steers fed the late fattening TMR diet (SLFT). Firmicutes and Bacteroidota were the first and second most dominant phyla in all the samples, respectively. The Firmicutes/Bacteroidota (F/B) ratio associated with feed efficiency was significantly greater in the SLFT group than in the other groups. At the genus level, Romboutsia, Paeniclostridium, and Turicibacterwere the most abundant in the SLFT while Akkermansia, Bacteroides, and Monoglobus were the most abundant in the HOTB group. Although the same early fattening TMR diet was fed to Hanwoo heifers and steers, Marvinbryantia and Coprococcus were the most abundant in the HEFT group while Alistipes and Ruminococcus were the most abundant in the SEFT group. Shannon and Simpson diversity indices were significantly lower in the SLFT group than in the other groups. Distribution of fecal microbiota and functional genetic profiles were significantly different among the four treatment groups. The present study demonstrates that different diets and genders can affect fecal microbiota and the F/B ratio may be associated with feed efficiency in Hanwoo cattle. Our results may help develop strategies to improve gut health and productivity through manipulation of fecal microbiota using the appropriate diet considering Hanwoo cattle gender.

The Distribution Characteristics of Aerosol Bacteria in Different Types of Pig Houses

Simple Summary

Microbial aerosols from pig houses can be released into the environment, posing a serious threat to biosafety and public health. At present, there are few studies on the structural characteristics of aerosol bacteria in piggeries at different growth stages. It is important to understand the characteristics of aerosol bacteria in pig houses to solve the problems of air pollution and disease control in pig houses at different growth stages. In this study, bacterial aerosol concentrations and bacterial communities were compared in pig houses at different growth stages in Hebei Province, China. It was found that bacterial concentrations, community richness, and diversity in the air increased with the age of pigs. There are many pathogenic bacteria in the microbial aerosols of piggery. Our study highlights the importance of more comprehensive research and analysis of microbial aerosols in pig houses. Precautions for air pollution should be instituted in pig houses, including wearing masks, rigorous disinfection, and hygiene procedures.

Abstract

With the development of modern pig raising technology, the increasing density of animals in pig houses leads to the accumulation of microbial aerosols in pig houses. It is an important prerequisite to grasp the characteristics of bacteria in aerosols in different pig houses to solve the problems of air pollution and disease prevention and control in different pig houses. This work investigated the effects of growth stages on bacterial aerosol concentrations and bacterial communities in pig houses. Three traditional types of closed pig houses were studied: farrowing (FAR) houses, weaning (WEA) houses, and fattening (FAT) houses. The Andersen six-stage sampler and high-volume air sampler were used to assess the concentrations and size distribution of airborne bacteria, and 16S rRNA gene sequencing was used to identify the bacterial communities. We found that the airborne bacterial concentration, community richness, and diversity index increased with pig age. We found that Acinetobacter, Erysipelothrix, Streptococcus, Moraxella, and Aerococcus in the microbial aerosols of pig houses have the potential risk of causing disease. These differences lead us to believe that disinfection strategies for pig houses should involve a situational focus on environmental aerosol composition on a case-by-case basis.

Particulate Matter in Swine Barns: A Comprehensive Review

Particulate matter (PM) represents an air quality management challenge for confined swine production systems. Due to the limited space and ventilation rate, PM can reach relatively high concentrations in swine barns. PM in swine barns possesses different physical, chemical, and biological characteristics than that in the atmosphere and other indoor environments. As a result, it exerts different environmental and health effects and creates some unique challenges regarding PM measurement and mitigation. Numerous research efforts have been made, generating massive data and information. However, relevant review reports are sporadic. This study aims to provide an updated comprehensive review of swine barn PM, focusing on publications since 1990. It covers various topics including PM characteristics, sources, measurement methods, and in-barn mitigation technologies. As PM in swine barns is primarily of biological origins, bioaerosols are reviewed in great detail. Relevant topics include bacterial/fungal counts, viruses, microbial community composition, antibiotic-resistant bacteria, antibiotic resistance genes, endotoxins, and (1→3)-β-D-glucans. For each topic, existing knowledge is summarized and discussed and knowledge gaps are identified. Overall, PM in swine barns is complicated in chemical and biological composition and highly variable in mass concentrations, size, and microbial abundance. Feed, feces, and skins constitute the major PM sources. Regarding in-barn PM mitigation, four technologies (oil/water sprinkling, ionization, alternation of feed and feeders, and recirculating air filtration) are dominant. However, none of them have been widely used in commercial barns. A collective discussion of major knowledge gaps and future research needs is offered at the end of the report.