María Cambra-López

Airborne particulate matter from livestock production systems: a review of an air pollution problem.

Livestock housing is an important source of emissions of particulate matter (PM). High concentrations of PM can threaten the environment, as well as the health and welfare of humans and animals. Particulate matter in livestock houses is mainly coarse, primary in origin, and organic; it can adsorb and contain gases, odorous compounds, and micro-organisms, which can enhance its biological effect. Levels of PM in livestock houses are high, influenced by kind of housing and feeding, animal type, and environmental factors. Improved knowledge on particle morphology, primarily size, composition, levels, and the factors influencing these can be useful to identify and quantify sources of PM more accurately, to evaluate their effects, and to propose adequate abatement strategies in livestock houses. This paper reviews the state-of-the-art of PM in and from livestock production systems. Future research to characterize and control PM in livestock houses is discussed.

Particulate matter emitted from poultry and pig houses: source identification and quantification

There is need to identify and quantify the contribution of different sources to airborne particulate matter (PM) emissions from animal houses. To this end, we compared the chemical and morphological characteristics of fine and coarse PM from known sources collected from animal houses with the characteristics of on-farm fine and coarse airborne PM using two methods: classification rules based on decision trees and multiple linear regression. Fourteen different farms corresponding to seven different housing systems for poultry and pigs were sampled during winter. A total of 28 fine and 28 coarse on-farm airborne PM samples were collected, together with a representative sample of each known source per farm (56 known source samples in total). Source contributions were calculated as relative percentage contributions in particle numbers and then estimated in particle mass. Based on particle numbers, results showed that in poultry houses, most on-farm airborne PM originated from feathers (ranging from 4% to 43% in fine PM and from 6% to 35% in coarse PM) and manure (ranging from 9% to 85% in fine PM and from 30% to 94% in coarse PM). For pigs, most on-farm airborne PM originated from manure (ranging from 70% to 98% in fine PM and from 41% to 94% in coarse PM). Based on particle mass, for poultry most on-farm airborne PM still originated from feathers and manure; for pigs, however, most PM originated from skin and manure. Feed had a negligible contribution to on-farm airborne PM compared with other sources. Results presented in this study improve the understanding of sources of PM in different animal housing systems, which may be valuable when choosing optimal PM reduction techniques.

Ionization for reducing particulate matter emissions from poultry houses.

We evaluated the effect of ionization in reducing particulate and gaseous emissions in broiler houses and its effect on particle size distribution. Furthermore, we evaluated the performance of the tested ionization system and its influence on bird performance. The experiment was done during two consecutive rearing cycles in a pilot-scale broiler house with four identical rooms. We measured concentrations of PM10 and PM2.5, airborne micro-organisms, ammonia, and odor of the incoming and outgoing air. Emissions were calculated by multiplying measured concentration difference of each pollutant by measured ventilation exchange rates. Performance of the system was evaluated through quantifying ion concentration, ozone production, and ultrafine particle concentration. Moreover, we recorded bird weight gain, consumption variables, mortality, exterior quality, and foot pad lesions. Overall measured mass emissions reductions were 36% for PM10 and 10% for PM2.5. Total mass was reduced less for PM2.5 because reduction efficiency decreased to the end of the growing period (P < 0.10). This coincided with increased particulate concentrations, increased ventilation exchange rates, and dust accumulation on surfaces. Higher reduction efficiencies were observed in relation to increased particle size. Ionization did not have a significant effect on micro-organism, ammonia, or odor emissions or on bird performance. Ionization proved to be a practical and effective technique for particulate reduction, with minimal maintenance required for use in broiler houses. It is recommended to evaluate the use of ionization in commercial broiler houses to validate these results.

The use of agricultural substrates to improve methane yield in anaerobic co-digestion with pig slurry: effect of substrate type and inclusion level.

Anaerobic co-digestion of pig slurry with four agricultural substrates (tomato, pepper, persimmon and peach) was investigated. Each agricultural substrate was tested in co-digestion with pig slurry at four inclusion levels: 0%, 15%, 30% and 50%. Inclusion levels consisted in the replacement of the volatile solids (VS) from the pig slurry with the VS from the agricultural substrate. The effect of substrate type and inclusion level on the biochemical methane potential (BMP) was evaluated in a batch assay performed at 35 °C for 100 days. Agricultural substrates chemical composition was also analyzed and related with BMP. Additionally, Bacteria and Archaea domains together with the four main methanogenic archaeal orders were quantified using quantitative real-time TaqMan polymerase chain reaction (qPCR) at the end of the experiment to determine the influence of agricultural substrate on sludges microbial composition. Results showed that vegetable substrates (pepper and tomato) had higher lipid and protein content and lower carbohydrates than fruit substrates (persimmon and peach). Among substrates, vegetable substrates showed higher BMP than fruit substrates. Higher BMP values were obtained with increasing addition of agricultural substrate. The replacement of 50% of VS from pig slurry by tomato and pepper increased BMP in 41% and 44%, respectively compared with pig slurry only. Lower increments in BMP were achieved with lower inclusion levels. Results from qPCR showed that total bacteria and total archaea gene concentrations were similar in all combinations tested. Methanomicrobiales gene concentrations dominated over the rest of individual archaeal orders.

Characterization of gas emissions from a Mediterranean broiler farm

Gas emissions from broiler production have been the subject of intensive research. However, little experimental information exists for farms under the particular management and environmental conditions of the European Mediterranean area. In this study, ammonia, carbon dioxide, methane, and nitrous oxide concentrations and emissions were measured in a commercial broiler farm located in Spain. Gas concentrations were measured using a photoacoustic gas monitor, whereas the ventilation flow was evaluated by controlling the operation status of each fan. Two rearing periods were studied, one in summer and one in winter. All gas emissions increased with bird age. Ammonia emission rates averaged 19.7 and 18.1 mg/h per bird in the summer and winter, respectively, and increased with indoor temperature (r(2) = 0.51 in summer; r(2) = 0.42 in winter). Average CO(2) emission rates were 3.84 and 4.06 g/h per bird, CH(4) emission was 0.44 and 1.87 mg/h per bird, and N(2)O emission was 1.74 and 2.13 mg/h per bird in summer and winter, respectively. A sinusoidal daily variation pattern was observed in all emissions except for CH(4). These patterns were characterized in terms of time of maximum emission and amplitude of the daily variation.

The influence of broiler activity, growth rate, and litter on carbon dioxide balances for the determination of ventilation flow rates in broiler production

Carbon dioxide balances are useful in determining ventilation rates in livestock buildings. These balances need an accurate estimation of the CO(2) produced by animals and their litter to determine the ventilation flows. To estimate the daily variation in ventilation flow, it is necessary to precisely know the daily variation pattern of CO(2) production, which mainly depends on animal activity. The objective of this study was to explore the applicability of CO(2) balances for determining ventilation flows in broiler buildings. More specifically, this work aimed to quantify the amount of CO(2) produced by the litter, as well as the amount of CO(2) produced by the broilers, as a function of productive parameters, and to analyze the influence of broiler activity on CO(2) emissions. Gas concentrations and ventilation flows were simultaneously measured in 3 trials, with 1 under experimental conditions and the other 2 in a commercial broiler farm. In the experimental assay, broiler activity was also determined. At the end of the experimental trial, on the day after the removal of the broilers, the litter accounted for 20% of the total CO(2) produced, and the broilers produced 3.71 L/h of CO(2) per kg of metabolic weight. On the commercial farm, CO(2) production was the same for the 2 cycles (2.60 L/h per kg of metabolic weight, P > 0.05). However, substantial differences were found between CO(2) and broiler activity patterns after changes in light status. A regression model was used to explain these differences (R(2) = 0.52). Carbon dioxide increased with bird activity, being on average 3.02 L/h per kg of metabolic weight for inactive birds and 4.73 L/h per kg of metabolic weight when bird activity was highest. Overall, CO(2) balances are robust tools for determining the daily average ventilation flows in broiler farms. These balances could also be applied at more frequent intervals, but in this case, particular care is necessary after light status changes because of discrepancy between animal activity and CO(2) production.

Viral shedding and emission of airborne infectious bursal disease virus from a broiler room

1. The significance of airborne transmission in epidemics of infectious diseases in the livestock production industry remains unclear. The study therefore investigated the shedding route (faeces vs. exhaled air) of a vaccine strain of infectious bursal disease virus (IBDV) by broilers and the emission of airborne virus. 2. The experimental room contained 526 broilers which were orally inoculated at the age of 20 d. The airborne virus was sampled by three different bioaerosol samplers: Andersen six-stage impactor, all-glass impinger (AGI-30) and OMNI-3000. 3. Infected broilers started to shed virus in faeces on d 5 post inoculation (PI), and stopped shedding on d 12 PI. The faecal virus remained detectable for at least two d after drying under broiler room conditions. No virus was detected in the air exhaled by broilers. 4. Airborne virus was collected on d 5, 8 and 12 PI at 20 cm above the floor, and on d 8 and 12 PI in exhausted air. The emission rates of IBDV were 4·0 log10 50% tissue culture infectious dose (TCID50)/bird/d on d 8 PI, and 4·5 log10 TCID50/bird/d on d 12 PI. 5. We concluded that broilers shed IBDV mainly through their faeces. The presence of indoor airborne virus is associated with the viral presence in faeces. The successful recovery of airborne virus in exhausted air indicates there is a potential risk of virus spreading to the ambient environment via air.

Microbial examination of anaerobic sludge adaptation to animal slurry

The objective of this study was to evaluate changes in the microbial population of anaerobic sludge digesters during the adaptation to pig slurry (PS) using quantitative real-time polymerase chain reaction (qPCR) and qualitative scanning electron microscopy (SEM). Additionally, the relationship between microbial parameters and sludge physicochemical composition and methane yield was examined. Results showed that the addition of PS to an unadapted thermophilic anaerobic digester caused an increase in volatile fatty acids (VFA) concentration, a decrease in removal efficiency and CH4 yield. Additionally, increases in total bacteria and total archaea were observed using qPCR. Scanning electron micrographs provided a general overview of the sludges cell morphology, morphological diversity and degree of organic matter degradation. A change in microbial morphotypes from homogeneous cell morphologies to a higher morphological diversity, similar to that observed in PS, was observed with the addition of PS by SEM. Therefore, the combination of qPCR and SEM allowed expanding the knowledge about the microbial adaptation to animal slurry in thermophilic anaerobic digesters.

Source identification and quantification of particulate matter emitted from livestock houses

It is necessary to accurately identify and quantify sources which contribute to particulate matter (PM) emissions from livestock houses to develop adequate reduction strategies. To identify and quantify the contribution of different sources to fine (PM2.5) and coarse (PM10-2.5) PM emissions from poultry and pig houses, we compared the chemical and morphological characteristics of fine and coarse PM from known sources collected from livestock houses with the characteristics of on-farm fine and coarse airborne PM. Two methods were used to estimate source contributions: classification rules based on decision trees and multiple linear regression. Results showed that in poultry houses, most on-farm airborne PM originates from feathers (ranging from 4 to 43% in fine and from 6 to 35% in coarse PM) and manure (ranging from 9 to 85% in fine and from 30 to 94% in coarse PM). In broilers and turkeys, wood shavings contribute less than 34% of particle numbers. In pigs, most on-farm airborne PM originates from manure (ranging from 70 to 98% in fine and from 41 to 94% in coarse PM). The contributions of wood shavings in poultry and skin in pigs were less than 34%, varying with livestock categories. The contribution of manure to on-farm airborne PM was higher in coarse PM in poultry, but higher in fine PM in pigs. Feed had a negligible contribution to on-farm airborne PM compared with the rest of the sources. Results presented in this study improve the understanding of where PM comes from in different livestock housing systems. This can be valuable to choose the optimal dust reduction methods.

Detection of airborne Salmonella spp. in poultry farms using impingement: culture-dependent vs. culture-independent methods.

Presence of airborne Salmonella species (spp). in poultry houses can pose a risk of infection to human and animal through airborne transmission route. The objective of this study was to assess the performance of impingement technique, followed by culture-dependent and culture-independent methods to detect airborne Salmonella spp. in rooms with experimentally inoculated birds. Broilers were inoculated at 7 days of age with a marked strain of Salmonella enteritidis. The rearing cycle lasted 42 days over the summer. Airborne Salmonella spp. was weekly sampled in each room with all-glass impingers (AGI-30). Presence of Salmonella spp. was determined by three culture-dependent methods (dilutions and plating, Most Probable Number-MPN and ISO 6579:2002); and by one culture-independent method (polymerase chain reaction, PCR). Additionally, Salmonella spp. was sampled on feeders, drinkers, walls, and in the litter. No cultivable Salmonella spp. on room floor and wall, feed or litter was recovered before bird inoculation. Salmonella spp. was detected on room surfaces after inoculation, and quantified in the litter in both rooms thereafter.