The effect of alum addition on microbial communities in poultry litter

Comparison of the Ammonia Trapping Performance of Different Gas-Permeable Tubular Membrane System Configurations

The technology of gas-permeable tubular membranes (GPMs) is promising in reducing ammonia emissions from livestock manure, capturing NH₃ in an acidic solution, and obtaining final products suitable for valorization as fertilizers, in line with the principles of the circular economy. This study aimed to evaluate the performance of several e-PTFE membrane systems with different configurations for the recovery of NH₃ released from pig slurry. Ten different configurations were tested: only a submerged membrane, only a suspended membrane in the same chamber, only a suspended membrane in an annex chamber, a submerged membrane + a suspended membrane in the same chamber, and a submerged membrane + a suspended membrane in an annex chamber, considering in each case the scenarios without and with agitation and aeration of the slurry. In all tests, sulfuric acid (1N H₂SO₄) was used as the NH₃ capture solution, which circulated at a flow rate of 2.1 L·h^-1. The results showed that NH₃-N removal rates ranged from 36-39% (for systems with a single submerged or suspended membrane without agitation or aeration of the slurry) to 70-72% for submerged + suspended GPM systems with agitation and aeration. In turn, NH₃-N recovery rates were found to be between 44-54% (for systems with a single membrane suspended in an annex compartment) and 88-91% (for systems based on a single submerged membrane). However, when choosing a system for farm deployment, it is essential to consider not only the capture and recovery performance of the system, but also the investment and operating costs (ranging from 9.8 to 21.2 €/kg N recovered depending on the selected configuration). The overall assessment suggests that the simplest systems, based on a single membrane, may be the most recommendable.

Management and environmental factors influence the prevalence and abundance of food-borne pathogens and commensal bacteria in peanut hull-based broiler litter

In this study, we conducted a longitudinal sampling of peanut hull-based litter from a farm under a "no antibiotics ever" program. Our objective was to determine broiler management practices and environmental factors that are associated with the occurrence of food-borne pathogens (Salmonella and Campylobacter) and the abundance of commensal bacteria (Escherichia coli, Enterococcus spp., and Staphylococcus spp.). Litter (n = 288) was collected from 4 broiler houses over three consecutive flocks, starting with a complete house cleanout and fresh peanut hull. Litter was sampled at the beginning of each grow-out cycle and at the end of the cycle. Logistic and linear regression models were used to model the relationships between pathogen prevalence, commensal abundance and management practices, and environmental factors. The number of flocks raised on litter, grow-out period, broiler house, litter pH, litter moisture, and house temperature were associated with the prevalence of pathogens and the abundance of commensal bacteria in litter. The final logistic model for pathogens showed that a higher probability of detecting Salmonella in litter was associated with the number of flocks raised on litter and the grow-out period. A higher probability of detecting Campylobacter in litter was associated with the number of flocks raised on litter, broiler house and the sections of the house, and the pH of litter. Our results suggest that management practices and environmental factors affect Salmonella and Campylobacter differently and suggest that each pathogen will require its own tailored intervention to stop their persistence in broiler litter.

Modified dietary fiber from cassava pulp affects the cecal microbial population, short-chain fatty acid, and ammonia production in broiler chickens

The objective of this study was to investigate the effects of modified dietary fiber from cassava pulp (M-DFCP) supplementation in broiler diets on cecal microbial populations, short-chain fatty acids (SCFAs), ammonia production, and immune responses. A total of 336, one-day-old male broiler chicks (Ross 308) were distributed over 4 dietary treatments in 7 replicate pens (n = 12 chicks) using a completely randomized design. Chicks were fed the control diet and 3 levels of M-DFCP (0.5, 1.0, and 1.5%) for an experimental duration of 42 d. The M-DFCP contained total dietary fiber (TDF), soluble dietary fiber (SDF), insoluble dietary fiber (IDF), cello-oligosaccharides (COS), and xylo-oligosaccharides (XOS) of approximately 280.70, 22.20, 258.50, 23.93, and 157.55 g/kg, respectively. The 1.0 and 1.5% M-DFCP supplementation diets showed positive effects on stimulating the growth of Lactobacillus spp. and Bifidobacterium spp., enhancing SCFAs (acetic, propionic, butyric acid, and branched SCFAs) and lactic acid concentrations during growing periods. Broilers fed 1.0 and 1.5% M-DFCP also exhibited a significant increase in caecal Lactobacillus spp. and lactic acid concentrations during the finisher period as well. In addition, M-DFCP also reduced cecal digesta and excreta ammonia production in broilers over both periods (0-21 and 22-42 d of age). However, M-DFCP did not exhibit any effect on total serum immunoglobulin (Ig) or lysozyme activity. In conclusion, this study shows that M-DFCP can be used as a dietary fiber source in broiler diets, with a recommended level of approximately 1.0%.

Dynamics and Diversity of Microbial Contamination in Poultry Bedding Materials Containing Parts of Medicinal Plants

Microorganisms thriving in poultry bedding materials during their exploitation are involved in the development of several diseases and disfunctions of animals. They can also contaminate food products and pose risks to the environment and human health. This study provides an analysis of dynamics and diversity in microbiological contamination observed during the exploitation of poultry bedding materials containing parts of medicinal plants: Satureja hortensis, Origanum vulgare, Melissa officinalis, Salvia officinalis, and Thymus vulgaris, compared with standard types of beddings: straw chaff and straw pellets. The research was carried out in two 42-day experimental cycles involving in total 2400 broiler chickens. Each week, the total count of mesophilic bacteria, fungi and yeasts, the presumptive presence and count of Staphylococcus sp., Escherichia sp., Listeria sp., Salmonella sp., and Candida sp. were determined by culturing on selective media, along with pH and moisture measurements. After 35 days of the experiment, a reduction of the total count of mesophilic bacteria above 1 log compared to the control (11.86 vs. 13.02 log CFU/g) was observed. As the count of yeasts decreased after 21 days, an increase in the total count of bacteria was reported, which indicates a strong competition between microorganisms. The results improve our understanding of the temporal effects of using materials containing parts of medicinal plants on the microbial contamination in poultry litter.

The effect of an acidified-gypsum mixture on broiler litter urease-producing bacteria and nitrogen mineralization

Ammonia (NH₃ ) volatilization from broiler (Gallus gallus domesticus) litter is a microbially mediated process that can decrease bird productivity and serves as an environmental pollutant. The release of NH₃ is strongly influenced by the pH of litter. Flue-gas desulfurization gypsum (FGDG) has been suggested as a potential amendment to reduce NH₃ volatilization due to the pH buffering capacity of calcium carbonate (CaCO₃ ) precipitation. However, its effect on litter pH is not as pronounced as acidifying agents, such as aluminum sulfate (alum). The main objective of our study was to develop an acidified-FGDG amendment that has a more pronounced effect on litter pH and NH₃ volatilization than FGDG alone. We conducted a 33-d incubation in which litter pH, NH₃ volatilization, nitrogen mineralization, PLUP-ureC gene abundance, and CaCO₃ precipitation were measured. Treatments in the study included: broiler litter (BL), broiler litter + 20% FGDG (BL+FGDG), broiler litter + FGDG-alum mixture (BL+FGDG+A6), broiler litter + 6% alum (BL+A6), and broiler litter + 10% alum (BL+A10). Our FGDG+alum amendment decreased litter pH (0.68 pH units) and PLUP-ureC gene abundance (>1 log) compared with FGDG alone and the control (p < .05). This led to a 25% decrease in cumulative NH₃ loss after 33 d. The addition of FGDG alone did not have an effect on litter pH (p = .36) or cumulative NH₃ loss (p = .29) due to a lack of significant CaCO₃ precipitation. Treating litter with 6 and 10% alum was the most effective amendment for reducing pH and cumulative NH₃ loss.

Succession patterns of the bacterial community in poultry litter after bird removal and sodium bisulfate application

Sulfate-based acid amendments are used for treating litter between broiler chicken flocks and during grow-out for in-house ammonia abatement. These amendments reduce litter pH and inhibit ammonia volatilization by converting ammonia to nonvolatile ammonium. Research on the effects of acid amendments on litter microbiota is limited and usually done in microcosms, which do not replicate natural environments. In this study, we determined the changes in bacterial populations present in litter during downtime (the period after a flock was removed and before new broiler chicks were placed) and 24 h before and after the application of a sodium bisulfate (NaHSO₄ )-based amendment. We used DNA sequencing technologies to characterize the litter microbiota, elucidating microbial shifts in litter samples with respect to downtime, litter depth, and NaHSO₄ application. During downtime (∼18 d), the litter microbiota was dominated by Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria. Sodium bisulfate affected the microbiota in the top layer (3 cm) of reused litter topdressed with fresh pine shavings and resulted in an increase in Escherichia spp. and Faecalibacterium spp. and a decrease in members of the phylum Acidobacteria. Furthermore, culturable Escherichia coli decreased by 1.5 log units during downtime, but an increase was observed for topdressed litter after NaHSO₄ was applied. Although the effect of acidifiers on ammonia reduction, bird performance, and litter performance are well documented, their effect on litter bacteria is not well understood. Our results suggest that acidifiers may perturb litter bacteria when topdressed with fresh pine shavings and that further research is required.

Effect of sodium bisulfate amendments on bacterial populations in broiler litter

The accumulation of ammonia in poultry houses is of concern to bird and human health. Acidification of the litter by application of acidifying amendments such as sodium bisulfate (SBS) retains ammonia generated by microbial degradation of uric acid as harmless ammonium in the litter. Although some studies on the effects of litter amendments on specific bacteria and groups of bacteria have been carried out previously, wide gaps in knowledge remain. In the present study, 2 types of samples were prepared and either left unamended or amended with 2.5 or 10% SBS. One set of samples consisted of a 1:1 mixture of built-up litter and fresh poultry manure (L/M); the other of fresh wood shavings and fresh poultry manure (S/M). The samples were kept in the laboratory at room temperature for 35 d. The pH of unamended mixtures increased to 7.3 and 6.9 for L/M and S/M, respectively. A pH of 6.7 and 3.9 on day 35 was observed for L/M and SM with 2.5% SBS, respectively. The corresponding values for LM and SM amended with 10% SBS were 3.5 and 2.5, respectively. Plating data indicated that coliforms became less numerous in the unamended samples than the SBS-amended samples. This difference was also seen in data obtained by high-throughput sequencing of 16S rDNA. The sequencing data also indicated that sequences from the genus Oceanisphaera accounted for as much as 80% of the sequences from L/M and about 40% of those from S/M samples early on. Sequences from members of the order Clostridiales were enriched in L/M and S/M amended with 10% SBS as were sequences from the genus Turicibacter. Weisella species sequences were more prevalent in SBS-amended samples than in unamended ones. Sequences from the genus Corynebacterium, Brachybacterium, and Arthrobacter were more common in L/M samples than in S/M samples regardless of the SBS content. The data indicate that litter amendments affect some bacteria populations and not others. Further studies are required to determine if the observed population changes such as increased survival of coliforms warrant actions to improve the microbial quality of litter to be reused.

Suitability of litter amendments for the Australian chicken meat industry

The Australian chicken meat indutstry is rapidly expanding due to the increasing consumption of chicken meat. As a result, the industry has growing issues of sourcing new bedding materials and disposing of spent litter, which can be attributed, in part, to a lack of widespread litter re-use for rearing chickens. According to insights and perspectives recently gathered from industry stakeholders, it is believed that re-using litter will become more common in the future, so as to reduce production costs and ease pressures on both the supply of new bedding materials and disposal of spent litter. However, there are potential risks that need to be addressed if litter re-use increases, particularly with regard to the production and mitigation of ammonia, which can negatively affect chicken health if not managed correctly. The present review discusses the potential benefits reported for different types of litter amendments, which have the primary goal of reducing ammonia volatilisation, but may also contribute to improvements in bird performance, welfare, pathogen loads, fertiliser value of spent litter, and reduced costs associated with purchasing new bedding materials. Acidifiers have been shown to be the most effective of all amendment types, with sodium bisulfate or alum being among the most commonly tested products mentioned in research literature. Litter amendments are currently rarely used in Australia, but it is hoped that the information provided in the present review, based mostly on overseas usage and research, will help inform future decision-making on the use of these products in Australian poultry production systems.

Amending Poultry Broiler Litter to Prevent the Development of Stable Fly, Stomoxys calcitrans (Diptera: Muscidae) and Other Nuisance Flies

Spent poultry litter use as a fertilizer in horticulture supports stable fly Stomoxys calcitrans (L.) (Diptera: Muscidae) development. Stable fly continues to have an economic impact on livestock production and rural lifestyle in south-western Australia. The use of raw poultry manure is banned in 12 Shires surrounding Perth. The loss of market options for West Australian broiler growers has caused economic hardship. Hence, this study examined a range of chemical and biological amendments to spent poultry broiler litter in preventing stable fly and nuisance fly development. These included alkalizers (i.e., lime sand, quicklime, soda ash, and shell grit), acidifiers (aluminum sulfate, sodium bisulfate), gypsum, zeolite, spongolite, calcium cyanamide, and two fungal agents. The treated litters were placed under irrigation in horticulture with amendments added prior to them being exposed in the field as replicate 1-liter pads. In total, 19,559 stable flies developed from the spent litters exposed over five field experiments (88.7% of all flies recovered). House flies (Musca domestica L. (Diptera: Muscidae); 2,067 or 9.4%), false stable flies (Muscina stabulans Fallén (Diptera: Muscidae); 414 or 1.9%), and two sarcophagids (flesh fly) also developed from the litter. Borax completely prevented any fly development from the litter. Calcium cyanamide (1-2.5% v/v) and sodium bisulfate (10%) reduced stable fly numbers by as much as 99-100% when added to litter. Alkalizers, zeolite, spongolite, and entomopathogenic fungi had no significant impact on stable fly development. The addition of either calcium cyanamide or sodium bisulfate to raw litter can boost the fertilizer value of the litter while preventing stable fly development.

The Contrasting Effects of Alum-Treated Chicken Manures and KH2PO4 on Phosphorus Behavior in Soils

Alum [KAl(SO)⋅12HO] is often added to chicken manure to limit P solubility after land application. This is generally ascribed to the formation of Al-PO complexes. However, Al-PO complex formation could be affected by the matrix of chicken manure, which varies with animal diet. Alum was added to KHPO (as a reference material) and two manures from typical chicken farms in China, one from an intensive farm (CMIF) and another from free-ranging chickens (CMFR). These were subsequently incubated with soils for 100 d to investigate P transformations. Alum reduced water-soluble colorimetrically reactive phosphorus (RP) from soils amended with manure more effectively than in soils amended with KHPO. Alum addition lowered Mehlich-3 RP in soils with CMFR but had no influence on Mehlich-3 RP in CMIF- or KHPO-amended soils. A comparison of P in digested Mehlich-3 extracts with RP in undigested samples showed significantly increased P in digests of alum-treated CMFR only. Fractionation data indicated that alum treatment increased P in the NHF-RP (Al-P) fraction only in soils with KHPO, but not in soils with manure treatments. Furthermore, NaOH-extracted nonreactive P was markedly higher in soil with alum-treated CMFR relative to normal CMFR. The CMFR manure was assumed to contain higher concentrations of organic P because these chickens were fed grains only. These results suggest that the formation of alum-organic P complexes may reduce P solubility. By comparing alum-treated KHPO and manures, it appears that organic matter in manure could interfere with the formation of Al-PO complexes.

A quality enhancement green strategy for broiler meat by application of turmeric (Curcuma longa) powder as litter amendment to affect microbes, ammonia emission, pH and moisture

 In multi-cultural Sri Lankan conditions, poultry meat is paramount importance in ensuring food security and improving nutrition. Issues as contact dermatitis and ammonia emission in broiler industry which caused by diminished litter parameters cause reduction of meat quality, profits and environmental conditions. Therefore use of Turmeric (Curcuma longa) (TM) powder as an antiseptic litter amendment at several application levels to enhance litter parameters with microbial demolition was attempted. Three months old broiler litter (2 kg) sample was taken and initial pH and moisture was determined. Turmeric was used to mix at levels of 0%, 1%, 3%, 5% and 8% (w/w). After mixing, 150 g of mixed litter was placed in container for each level of the 4 replicates, incubated for 5h and analyzed for Total Plate Count (TPC), Yeast and Mold Count (YMC), total Nematode Count (NC), ammonia emission, pH and moisture. Significant reduction (p <0.05) of total bacteria was seen (20%, 46%, 95% and 96%) when 1%, 3%, 5% and 8% applications of TM. The YMC reduction was also significant (p <0.05) (34%, 41%, 55% and 65%). Total nematode reduction (p <0.05) was 22%, 45%, 62.5% and 70%. A significant (p <0.05) pH reduction with increment of TM also seen (0.1, 2, 3 and 3%). Moisture (%) was increased (p <0.05) (6, 0.78, 19 and 1%). Ammonia emission was significantly decreased (p <0.05) by increased TM (64, 68, 73 and 84%) against control. It was concluded that the bacterial, fungal, nematode counts, pH and Ammonia emission of broiler litter can be significantly reduced with the application of 8% (w/w) of turmeric powder.

Stacking Time and Aluminum Sulfate Effects on Polyether Ionophores in Broiler Litter

The use of ionophores as antiparasitic drugs plays an important role in US poultry production, especially in the broiler () industry. However, administered ionophores can pass through the bird's digestive system and appear in broiler litter, which, when applied to agricultural fields, can present an environmental hazard. Stacking (storing or stockpiling) broiler litter for some time might decrease the litter ionophore concentrations before land application. Because ionophores undergo abiotic hydrolysis at low pH, decreasing litter pH with acidic aluminum sulfate (alum) might also decrease ionophore concentrations. We assessed the change in ionophore concentrations in broiler litter in response to the length of time broiler litter was stored (stacking time) and alum addition. We spiked broiler litter with monensin and salinomycin, placed alum-amended litter (∼pH 4-5) and unamended litter (∼pH 8-9) into 1.8-m bins, and repeatedly sampled each bin for 112 d. Our findings showed that stacking broiler litter alone did not have an impact on monensin concentration, but it did slowly reduce salinomycin concentration by 55%. Adding alum to broiler litter reduced monensin concentration by approximately 20% relative to unamended litter, but it did not change salinomycin concentration. These results call for continued search for alternative strategies that could potentially reduce the concentration of ionophores in broiler litter before their application to agricultural soils.

Effects of Chicken Litter Storage Time and Ammonia Content on Thermal Resistance of Desiccation-Adapted Salmonella spp

Broiler chicken litter was kept as a stacked heap on a poultry farm, and samples were collected up to 9 months of storage. Chicken litter inoculated with desiccation-adapted Salmonella cells was heat-treated at 75, 80, 85, and 150°C. Salmonella populations decreased in all these samples during heat treatment, and the inactivation rates became lower in chicken litter when storage time was extended from 0 to 6 months. There was no significant difference (P > 0.05) in thermal resistance of Salmonella in 6- and 9-month litter samples, indicating that a threshold for thermal resistance was reached after 6 months. Overall, the thermal resistance of Salmonella in chicken litter was affected by the storage time of the litter. The changes in some chemical, physical, and microbiological properties during storage could possibly contribute to this difference. Moisture and ammonia could be two of the most significant factors influencing the thermal resistance of Salmonella cells in chicken litter. Our results emphasize the importance of adjusting time and temperature conditions for heat processing chicken litter when it is removed from the chicken house at different time intervals.

Effect of Alum Additions to Poultry Litter on In-House Ammonia and Greenhouse Gas Concentrations and Emissions

Alum [Al(SO4) ·14HO] addition to poultry litter has been shown to reduce ammonia (NH) concentrations in poultry houses; however, its effects on greenhouse gas (GHG; NO, CH, and CO) emissions is unknown. The objectives of this study were to determine the effects of alum additions on (i) in-house NH and GHG concentrations, (ii) NH and GHG emissions, and (iii) litter chemical properties. Two identical broiler houses located in northwest Arkansas were used for this study: one house was a control and the other was treated with alum between each flock of birds. Ventilation rates were coupled with in-house NH and GHG measurements to determine emission rates. Overall, alum additions significantly reduced the daily average in-house NH concentration by 42% (8.9 vs. 15.4 μL L), and the overall NH emission rate was reduced by 47% (7.2 vs. 13.4 kg d house). The average cumulative NH emission for the three flocks was 330 kg house flock for the alum-treated house and 617 kg house flock for the control. Concentrations and emissions of nitrous oxide (NO) and methane (CH) from the alum-treated house were not significantly different than the untreated house. However, carbon dioxide (CO) emissions were significantly higher from the untreated house than the alum-treated house. Alum also significantly increased litter N content and reduced the C/N ratio. These results indicate that the addition of alum to poultry litter is not only an effective management practice for reducing in-house NH concentrations and emissions but also significantly reduces CO emissions from poultry facilities.

Microbial communities present in the lower respiratory tract of clinically healthy birds in Pakistan

Commercial poultry is an important agricultural industry worldwide. Although dense living conditions and large flocks increase meat and egg production, they also increase the risk of disease outbreaks and zoonoses. Current pathogen identification methods mostly rely on culture-dependent techniques and, therefore, are limited to a very small number of bacteria present in the environment. Next Generation Sequencing allows for culture-independent characterization of lower respiratory microbiome of birds including the identification of novel commensals and potentially emerging pathogens. In this study, we collected tracheo-bronchoalveolar lavage of 14 birds raised at 3 different farms in the Punjab province of Pakistan. To characterize the lower respiratory microbiome of these birds, we sequenced hyper-variable regions of the 16S ribosomal subunit gene. Although dominated by bacteria belonging to a small number of taxonomic classifications, the lower respiratory microbiome from each farm was far more diverse and novel than previously known. The differences in microbiome among farms suggest that inter-farm differences affect the microbiome of birds more than breed, geographic location, or management system. The presence of potential and known pathogens in genetically similar specialty breeds of chickens kept at unnaturally high densities and under variable conditions presents an extraordinary opportunity for the selection of highly pathogenic bacteria. In some instances, opportunistic respiratory pathogens were observed in apparently healthy birds. Understanding and monitoring the respiratory microbiome of such populations may allow the early detection of future disease threats.

Acidification of animal slurry--a review

Ammonia emissions are a major problem associated with animal slurry management, and solutions to overcome this problem are required worldwide by farmers and stakeholders. An obvious way to minimize ammonia emissions from slurry is to decrease slurry pH by addition of acids or other substances. This solution has been used commonly since 2010 in countries such as Denmark, and its efficiency with regard to the minimization of NH3 emissions has been documented in many studies. Nevertheless, the impact of such treatment on other gaseous emissions during storage is not clear, since the studies performed so far have provided different scenarios. Similarly, the impact of the soil application of acidified slurry on plant production and diffuse pollution has been considered in several studies. Also, the impact of acidification upon combination with other slurry treatment technologies (e.g. mechanical separation, anaerobic digestion …) is important to consider. Here, a compilation and critical review of all these studies has been performed in order to fully understand the global impact of slurry acidification and assess the applicability of this treatment for slurry management.

A hybrid DNA extraction method for the qualitative and quantitative assessment of bacterial communities from poultry production samples

The efficacy of DNA extraction protocols can be highly dependent upon both the type of sample being investigated and the types of downstream analyses performed. Considering that the use of new bacterial community analysis techniques (e.g., microbiomics, metagenomics) is becoming more prevalent in the agricultural and environmental sciences and many environmental samples within these disciplines can be physiochemically and microbiologically unique (e.g., fecal and litter/bedding samples from the poultry production spectrum), appropriate and effective DNA extraction methods need to be carefully chosen. Therefore, a novel semi-automated hybrid DNA extraction method was developed specifically for use with environmental poultry production samples. This method is a combination of the two major types of DNA extraction: mechanical and enzymatic. A two-step intense mechanical homogenization step (using bead-beating specifically formulated for environmental samples) was added to the beginning of the "gold standard" enzymatic DNA extraction method for fecal samples to enhance the removal of bacteria and DNA from the sample matrix and improve the recovery of Gram-positive bacterial community members. Once the enzymatic extraction portion of the hybrid method was initiated, the remaining purification process was automated using a robotic workstation to increase sample throughput and decrease sample processing error. In comparison to the strict mechanical and enzymatic DNA extraction methods, this novel hybrid method provided the best overall combined performance when considering quantitative (using 16S rRNA qPCR) and qualitative (using microbiomics) estimates of the total bacterial communities when processing poultry feces and litter samples.

Microbial ecology, bacterial pathogens, and antibiotic resistant genes in swine manure wastewater as influenced by three swine management systems

The environmental influence of farm management in concentrated animal feeding operations (CAFO) can yield vast changes to the microbial biota and ecological structure of both the pig and waste manure lagoon wastewater. While some of these changes may not be negative, it is possible that CAFOs can enrich antibiotic resistant bacteria or pathogens based on farm type, thereby influencing the impact imparted by the land application of its respective wastewater. The purpose of this study was to measure the microbial constituents of swine-sow, -nursery, and -finisher farm manure lagoon wastewater and determine the changes induced by farm management. A total of 37 farms were visited in the Mid-South USA and analyzed for the genes 16S rRNA, spaQ (Salmonella spp.), Camp-16S (Campylobacter spp.), tetA, tetB, ermF, ermA, mecA, and intI using quantitative PCR. Additionally, 16S rRNA sequence libraries were created. Overall, it appeared that finisher farms were significantly different from nursery and sow farms in nearly all genes measured and in 16S rRNA clone libraries. Nearly all antibiotic resistance genes were detected in all farms. Interestingly, the mecA resistance gene (e.g. methicillin resistant Staphylococcus aureus) was below detection limits on most farms, and decreased as the pigs aged. Finisher farms generally had fewer antibiotic resistance genes, which corroborated previous phenotypic data; additionally, finisher farms produced a less diverse 16S rRNA sequence library. Comparisons of Camp-16S and spaQ GU (genomic unit) values to previous culture data demonstrated ratios from 10 to 10,000:1 depending on farm type, indicating viable but not cultivatable bacteria were dominant. The current study indicated that swine farm management schemes positively and negatively affect microbial and antibiotic resistant populations in CAFO wastewater which has future "downstream" implications from both an environmental and public health perspective.

The effect of alum coagulation for in-lake treatment of toxic Microcystis and other cyanobacteria related organisms in microcosm experiments

Microcosm and bottle experiments were conducted to evaluate the effects of alum treatment on cyanobacteria-lysing organisms and microcystin-degrading bacteria as well as Microcystis cells, and to provide detailed evidence of Microcystis cell damage by investigating precipitated Microcystis cells. The alum concentration to be pH 6.0 is the maximum which does not cause toxicity by monomeric Al, therefore, this concentration was defined as maximum dose. Microcystis cells were considerably damaged by the alum treatment with maximum dose and long contact time. Seven days post-treatment, intracellular microcystin-LR was released into the extracellular environment in excess of 95 percent and chlorophyll a is not easily released from inside the cell, chl.a of precipitated Microcystis cells was also decreased to approximately 50 percent. Moreover, alum treatment caused damage to cyanobacteria-lysing organisms and microcystin-degrading bacteria, as well as to Microcystis cells. Therefore, it could be concluded that alum treatment with maximum dose (48 mg L(-1) as AI) is not suitable for removing cyanobacterial bloom without the release of cyanotoxin in reservoirs and ponds.

Recovery of ammonia from poultry litter using flat gas permeable membranes

The use of flat gas-permeable membranes was investigated as components of a new process to capture and recover ammonia (NH3) in poultry houses. This process includes the passage of gaseous NH3 through a microporous hydrophobic membrane, capture with a circulating dilute acid on the other side of the membrane, and production of a concentrated ammonium (NH4) salt. Bench- and pilot-scale prototype systems using flat expanded polytetrafluoroethylene (ePTFE) membranes and a sulfuric acid solution consistently reduced headspace NH3 concentrations from 70% to 97% and recovered 88% to 100% of the NH3 volatilized from poultry litter. The potential benefits of this technology include cleaner air inside poultry houses, reduced ventilation costs, and a concentrated liquid ammonium salt that can be used as a plant nutrient solution.

Biosecurity-based interventions and strategies to reduce Campylobacter spp. on poultry farms

The prevention and control of Campylobacter colonization of poultry flocks are important public health strategies for the control of human campylobacteriosis. A critical review of the literature on interventions to control Campylobacter in poultry on farms was undertaken using a systematic approach. Although the focus of the review was on aspects appropriate to the United Kingdom poultry industry, the research reviewed was gathered from worldwide literature. Multiple electronic databases were employed to search the literature, in any language, from 1980 to September 2008. A primary set of 4,316 references was identified and scanned, using specific agreed-upon criteria, to select relevant references related to biosecurity-based interventions. The final library comprised 173 references. Identification of the sources of Campylobacter in poultry flocks was required to inform the development of targeted interventions to disrupt transmission routes. The approach used generally involved risk factor-based surveys related to culture-positive or -negative flocks, usually combined with a structured questionnaire. In addition, some studies, either in combination or independently, undertook intervention trials. Many of these studies were compromised by poor design, sampling, and statistical analysis. The evidence for each potential source and route of transmission on the poultry farm was reviewed critically, and the options for intervention were considered. The review concluded that, in most instances, biosecurity on conventional broiler farms can be enhanced and this should contribute to the reduction of flock colonization. However, complementary, non-biosecurity-based approaches will also be required in the future to maximize the reduction of Campylobacter-positive flocks at the farm level.

Impacts of poultry house environment on poultry litter bacterial community composition

Viral and bacterial pathogens are a significant economic concern to the US broiler industry and the ecological epicenter for poultry pathogens is the mixture of bedding material, chicken excrement and feathers that comprises the litter of a poultry house. This study used high-throughput sequencing to assess the richness and diversity of poultry litter bacterial communities, and to look for connections between these communities and the environmental characteristics of a poultry house including its history of gangrenous dermatitis (GD). Cluster analysis of 16S rRNA gene sequences revealed differences in the distribution of bacterial phylotypes between Wet and Dry litter samples and between houses. Wet litter contained greater diversity with 90% of total bacterial abundance occurring within the top 214 OTU clusters. In contrast, only 50 clusters accounted for 90% of Dry litter bacterial abundance. The sixth largest OTU cluster across all samples classified as an Arcobacter sp., an emerging human pathogen, occurring in only the Wet litter samples of a house with a modern evaporative cooling system. Ironically, the primary pathogenic clostridial and staphylococcal species associated with GD were not found in any house; however, there were thirteen 16S rRNA gene phylotypes of mostly gram-positive phyla that were unique to GD-affected houses and primarily occurred in Wet litter samples. Overall, the poultry house environment appeared to substantially impact the composition of litter bacterial communities and may play a key role in the emergence of food-borne pathogens.

Evaluation of nitrogen retention and microbial populations in poultry litter treated with chemical, biological or adsorbent amendments

Poultry litter is a valuable nutrient source for crop production. Successful management to reduce ammonia and its harmful side-effects on poultry and the environment can be aided by the use of litter amendments. In this study, three acidifiers, two biological treatments, one chemical urease inhibitor and two adsorber amendments were added to poultry litter. Chemical, physical and microbiological properties of the litters were assessed at the beginning and the end of the experiment. Application of litter amendments consistently reduced organic N loss (0-15%) as compared to unamended litter (20%). Acidifiers reduced nitrogen loss through both chemical and microbiological processes. Adsorbent amendments (water treatment residuals and chitosan) reduced nitrogen loss and concentrations of ammonia-producing bacteria and fungi. The use of efficient, cost-effective litter amendments to maximum agronomic, environmental and financial benefits is essential for the future of sustainable poultry production.

Bacterial diversity characterization of bioaerosols from cage-housed and floor-housed poultry operations

BACKGROUND

Although bioaerosols from both cage-housed (CH) and floor-housed (FH) poultry operations are highly concentrated, workers from CH operations have reported a greater prevalence of respiratory symptoms.

OBJECTIVE

The objective of this study was to directly compare bacteria, both quantitatively and qualitatively, in bioaerosols from CH and FH poultry facilities.

METHODS

Bioaerosols were collected from fifteen CH and fifteen FH poultry operations, using stationary area samplers as well as personal sampling devices. Dust, endotoxin and bacteria were quantified and bacterial diversity was investigated using PCR followed by denaturing gradient gel electrophoresis (DGGE).

RESULTS

Dust (p<0.001), endotoxin (p<0.05) and bacteria (p<0.05) were significantly higher in personal bioaerosols of FH poultry operations than CH bioaerosols. Although dust and endotoxin did not differ significantly between area and personal samples within each barn type, clustering analysis of DGGE profiles of bacteria revealed that area and personal samples shared less than 10% similarity. These data suggest that area samples are not representative of personal bacteria exposures, which may be affected by worker movement, bacteria carried on the worker and worker location. Personal DGGE profiles from CH and FH operations shared less than 20% similarity and composite analysis showed that bacteria were more prevalent in personal samples from CH bioaerosols than FH bioaerosols.

CONCLUSIONS

Bacteria concentration and diversity are significantly different between bioaerosols from CH and FH poultry operations.

Microbial mineralization of organic nitrogen forms in poultry litters

Ammonia volatilization from the mineralization of uric acid and urea has a major impact on the poultry industry and the environment. Dry acids are commonly used to reduce ammonia emissions from poultry houses; however, little is known about how acidification affects the litter biologically. The goal of this laboratory incubation was to compare the microbiological and physiochemical effects of dry acid amendments (Al+Clear, Poultry Litter Treatment, Poultry Guard) on poultry litter to an untreated control litter and to specifically correlate uric acid and urea contents of these litters to the microbes responsible for their mineralization. Although all three acidifiers eventually produced similar effects within the litter, there was at least a 2-wk delay in the microbiological responses using Poultry Litter Treatment. Acidification of the poultry litter resulted in >3 log increases in total fungal concentrations, with both uricolytic (uric acid degrading) and ureolytic (urea degrading) fungi increasing by >2 logs within the first 2 to 4 wk of the incubation. Conversely, total, uricolytic, and ureolytic bacterial populations all significantly declined during this same time period. While uric acid and urea mineralization occurred within the first 2 wk in the untreated control litter, acidification resulted in delayed mineralization events for both uric acid and urea (2 and 4 wk delay, respectively) once fungal cell concentrations exceeded a threshold level. Therefore, fungi, and especially uricolytic fungi, appear to have a vital role in the mineralization of organic N in low-pH, high-N environments, and the activity of these fungi should be considered in best management practices to reduce ammonia volatilization from acidified poultry litter.

Interrelations between the microbiotas in the litter and in the intestines of commercial broiler chickens

The intestinal microbiota of broiler chickens and the microbiota in the litter have been well studied, but the interactions between these two microbiotas remain to be determined. Therefore, we examined their reciprocal effects by analyzing the intestinal microbiotas of broilers reared on fresh pine shavings versus reused litter, as well as the litter microbiota over a 6-week cycle. Composite ileal mucosal and cecal luminal samples from birds (n = 10) reared with both litter conditions (fresh versus reused) were collected at 7, 14, 21, and 42 days of age. Litter samples were also collected at days 7, 14, 21, and 42. The microbiotas were profiled and compared within sample types based on litter condition using PCR and denaturing gradient gel electrophoresis (PCR-DGGE). The microbiotas were further analyzed using 16S rRNA gene clone libraries constructed from microbiota DNA extracted from both chick intestinal and litter samples collected at day 7. Results showed significant reciprocal effects between the microbiotas present in the litter and those in the intestines of broilers. Fresh litter had more environmental bacteria, while reused litter contained more bacteria of intestinal origin. Lactobacillus spp. dominated the ileal mucosal microbiota of fresh-litter chicks, while a group of bacteria yet to be classified within Clostridiales dominated in the ileal mucosal microbiota in the reused-litter chicks. The Litter condition (fresh versus reused) seemed to have a more profound impact on the ileal microbiota than on the cecal microbiota. The data suggest that the influence of fresh litter on ileal microbiota decreased as broilers grew, compared with temporal changes observed under reused-litter rearing conditions.

Matrix-based fertilizers reduce nutrient and bacterial leaching after manure application in a greenhouse column study

We tested the efficacy of matrix-based fertilizers (MBFs) to reduce Escherichia coli and Enterococcus spp., NH(4), NO(3), dissolved reactive phosphorus (DRP), and total phosphorus (TP) in leachate and soil after dairy manure application in greenhouse column studies. The MBFs are composed of inorganic N and P in compounds that are relatively loosely bound (MBF8) to more tightly bound (MBF9) mixtures using combinations of starch, cellulose, lignin, Al(2)(SO(4))(3)18H(2)O, and/or Fe(2)(SO(4))(3)3H(2)O to create a matrix that slowly releases the nutrients. One day after the first dairy manure application, E. coli numbers were greater in leachate from control columns than in leachate from columns receiving MBFs. After three dairy manure applications, E. coli and Enterococcus spp. numbers in leachates were not consistently different between controls and columns receiving MBFs. When MBF8 was applied to the soil, the total amount of DRP, TP, NH(4), and NO(3) in leachate was lower than in the control columns. Bermudagrass receiving MBFs had greater shoot, root, and total biomass than grass growing in the control columns. Grass shoot, root, and total biomass did not differ among columns receiving MBFs. Nitrogen and phosphorus bound to the Al(2)(SO(4))(3)18H(2)O or Fe(2)(SO(4))(3)3H(2)O-lignin-cellulose matrix become gradually available to plants over the growing season. The MBF8 and MBF9 formulations do not depend on organic or inorganic coatings to reduce N and P leaching and have the potential with further testing and development to provide an effective method to reduce N and P leaching from soils treated with animal waste.

Advances in enteropathogen control in poultry production

Poultry meat has been associated frequently and consistently with the transmission of enteric pathogens, including Salmonella and Campylobacter. This association has resulted in the development of HACCP-based intervention strategies. These strategies (hurdles) begin with elite breeder flocks and filter down the production pyramid. These hurdles include those already established, such as biosecurity, vaccination, competitive exclusion, pre- and probiotics, feed and water control, and those more experimental, such as bacteriophage or immunoglobulin therapy. The reduction in enteropathogens entering the processing plant, which employs critical control points, further reduce the exposure of consumers to these organisms. The synergistic application of hurdles will result in an environment that is restrictive and detrimental to enteropathogen colonization and contamination.

Effect of alum treatment on the concentration of total and ureolytic microorganisms in poultry litter

Microbial mineralization of urea and uric acid in poultry litter results in the production of ammonia, which can lead to decreased poultry performance, malodorous emissions, and loss of poultry litter value as a fertilizer. Despite the fact that this is a microbial process, little is known about how the microbial populations, especially ammonia-producing (ureolytic) organisms in poultry litter, respond to litter amendments such as aluminum sulfate (Al(2)(SO(4))(3).14H(2)O; alum). The goal of this study was to measure the temporal changes in total bacterial and fungal populations and urease-producing microorganisms in nontreated litter or litter treated with 10% alum. Quantitative real-time polymerase chain reaction was used to target the bacterial 16S rRNA gene, the fungal 18S rRNA gene, or the urease gene of bacterial and fungal ammonia producers in a poultry litter incubation study. Nontreated poultry litter had relatively high total (2.8 +/- 0.8 x 10(10) cells g(-1) litter) and ureolytic (2.8 +/- 1.3 x 10(8) cells g(-1) litter) bacterial populations. Alum treatment reduced the total bacterial population by 50% and bacterial urease producers by 90% within 4 wk. In contrast, at 16 wk after alum treatment, the fungal population was three orders of magnitude higher in alum-treated litter than in nontreated litter (3.5 +/- 0.8 x 10(7) cells g(-1) litter and 5.5 +/- 2.5 x 10(4) cells g(-1) litter, respectively). The decrease in pH produced by alum treatment is believed to inhibit bacterial populations and favor growth of fungi that may be responsible for the mineralization of organic nitrogen in alum-treated litters.