A.J.A. Aarnink

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.

Odour from animal production facilities: its relationship to diet

Though bad odour has always been associated with animal production, it did not attract much research attention until in many countries the odour production and emission from intensified animal production caused serious nuisance and was implicated in the health problems of individuals living near animal farms. Odour from pig production facilities is generated by the microbial conversion of feed in the large intestine of pigs and by the microbial conversion of pig excreta under anaerobic conditions and in manure stores. Assuming that primary odour-causing compounds arise from an excess of degradable protein and a lack of specific fermentable carbohydrates during microbial fermentation, the main dietary components that can be altered to reduce odour are protein and fermentable carbohydrates. In the present paper we aim to give an up-to-date review of studies on the relationship between diet composition and odour production, with the emphasis on protein and fermentable carbohydrates. We hypothesise how odour might be changed and/or reduced by altering the diet of pigs. Research so far has mainly focused on the single effects of different levels of crude protein and fermentable carbohydrates on odour production. However, also important for odour formation are the sources of protein and fermentable carbohydrates. In addition, it is not only the amount and source of these compounds that is important, but also the balance between them. On the basis of our review of the literature, we hypothesise that odour nuisance from pig production facilities might be reduced significantly if there is an optimum balance between protein and fermentable carbohydrates in the diet of pigs.

Ammonia emissions from pig houses in The Netherlands, Denmark and France

In recent decades pig production has been intensified in most European countries. This has resulted in a surplus of manure and a serious concern about the effect of ammonia emissions on environmental acidification and the pollution of ground and surface water. In the Netherlands, Denmark and France approximately 50% of the ammonia emissions from pig production is from pig housing and slurry storage. Ammonia emissions from pig houses can be reduced by: (1) lowering the concentrations of urea and ammonia in the slurry; (2) lowering the temperature of the slurry; (3) reducing the emitting surface area; (4) reducing the pH of the slurry. Various housing techniques have been developed to reduce ammonia emissions. Most of these techniques are costly but cheaper systems are becoming available. A combination of housing and feeding measures seems most promising to achieve a substantial reduction in ammonia emissions at relatively low costs. Lowering the protein content of the diet, including non-starch polysaccharides and adding acidifying salts instead of CaCO3 are the main possibilities at the moment to reduce the ammonia emission by dietary means.

Nitrogen and phosphorus consumption, utilisation and losses in pig production: The Netherlands

In recent years pig production has been intensified in most European countries. This has resulted in a surplus of manure, exceeding the nutrient needs of the plants. In The Netherlands different laws have been introduced since 1984 to reduce these environmental problems. In this paper the development of pig production in The Netherlands, the environmental pollution by pigs and the policies to limit it are described. In addition, the approach in The Netherlands to reducing phosphorus and nitrogen excretion and ammonia emissions by means of nutrition is discussed. Finally, the potential and means for reducing the environmental problems in practical pig farming in the future by feeding and management measures are described.

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.

Effects of dust and airborne dust components on antibody responses, body weight gain, and heart morphology of broilers

Pathogen-associated molecular patterns (PAMP) such as lipopolysaccharide (LPS), lipoteichoic acid, beta-glucans (BGL), and possibly many others are important parts of (fine) dust in animal houses. When intratracheally (i.t.) administered, PAMP affected specific primary and secondary humoral immune responses to concurrently i.t. or systemically administered antigens and BW gain (BWG) of layer chickens. In the present study, we evaluated the effects of i.t. challenge with various PAMP known to be present in dust: LPS, lipoteichoic acid, zymosan-A (containing 1,3 BGL), next to heat-inactivated dust particles as a representative of mechanical stress, a combination of the former components, and NH3 as a chemical component of dust on primary and secondary (total) systemic antibody (Ab) responses and (isotype) IgM and IgG responses to concurrently i.t.-administered human serum albumin (HuSA) in broilers. Birds were challenged via the trachea for 2 consecutive days at 3 and 7 wk of age, respectively. All treatments affected immune responses at several moments, BWG, and heart morphology. beta-Glucans and LPS affected the birds most pronounced and for a prolonged period. Intratracheally administered LPS and BGL significantly enhanced primary and secondary total Ab, IgM Ab, and IgG Ab responses to HuSA. All birds that were challenged with dust, PAMP, or NH3 concurrently with HuSA showed a decreased BWG especially after primary, but also after secondary challenge. Weight, width, and length of hearts were enhanced in dust and PAMP-treated birds as well when these birds were challenged with HuSA. The present results indicated that components of dust such as PAMP when i.t. administered affect humoral immune responsiveness of broilers, which may lead to an enhanced status of immune reactivity. Furthermore, our results suggest that the hygienic status of the environment influences BWG and may affect heart morphology, and as a consequence physiology in broilers. The consequences of our findings with respect to dust, (airborne) PAMP, hygienic conditions in the barn, and immune responsiveness of broilers are discussed.

EFFECTS OF ENVIRONMENTAL FACTORS ON ODOR EMISSION FROM PIG MANURE

Altering environmental factors may change odor emission from pig manure. The main objective of this laboratory-scale study was to examine the effects of temperature, ventilation rate, emitting area, and manure dilution ratio on odor emission from growing pig manure, while also testing their effects on manure characteristics. Manure was placed in vessels with different surfaces (303, 475, and 595 cm2), and water was added to create different dilution ratios (0%, 50%, and 100%). The vessels were connected to glass capillaries with different ventilation rates through the headspace (0.5, 1.0, and 1.5 L min-1) and were placed in climate-controlled rooms with different temperatures (10°C, 20°C, and 30°C). We used a face-centered central composite design with 54 experimental units in two rounds of three blocks. Odor samples were taken at the end of experiment (after seven days). Manure samples were collected at the start and at the end of the experiment. The mean odor emission from the manure vessel was 2326 ouE h-1 m-2. Increased temperature, ventilation rate, and dilution ratio increased odor emission. Emitting area did not influence odor emission, but positively influenced total-N loss. Total-N loss increased as temperature and ventilation rate increased, but decreased as dilution ratio increased. Lowering temperature and ventilation rate can be considered as starting points to reduce odor emission from pig manure in practical conditions. The effects of dilution ratio and emitting area on odor emission could not be fully separated from the effect of headspace volume in this study and should be further studied.

EFFECTS OF FLOOR COOLING DURING HIGH AMBIENT TEMPERATURES ON THE LYING BEHAVIOR AND PRODUCTIVITY OF GROWING FINISHING PIGS

Given that exposing rapidly growing pigs to high ambient temperatures can induce heat stress, which reduces their welfare and production, this study looked at the influence of floor cooling on pigs’ behavior and performance. Pens in room 1 had a solid floor (60%) and a metal slatted floor (40%). The pens in room 2 had a concrete slatted floor at the front (15%), then a convex solid floor (45%), and a metal slatted floor at the back (40%). Each room was stocked with 144 pigs with a starting weight of around 29.3 kg (±4.1 kg). The area per pig was approximately 1.0 m2. In half of the pens in each room, the floor could be cooled by cold water. The floor cooling was activated at ambient temperatures above 25°C in week 3 and above 20°C from week 7 onwards. Feed and water were accessible ad libitum. Cooling lowered the surface temperature of the solid floor (25.0°C vs. 26.8°C, P < 0.001), reduced the percentage of pigs lying on the slatted floor (15.0% vs. 22.2%; P < 0.001), and increased feed intake (2.04 vs. 1.95 kg d-1 pig-1, P < 0.01) and growth rate (753.2 vs. 720.4 g d-1; P = 0.017). Cooling and pen design affected fouling of the solid floor. The cooled pens were cleaner than the uncooled pens, and the pens in room 2 were cleaner than those in room 1. These results show that floor cooling can improve the thermal comfort and performance of intensively reared growing and finishing pigs during hot weather.

Life cycle assessment of segregating fattening pig urine and feces compared to conventional liquid manure management

Gaseous emissions from in-house storage of liquid animal manure remain a major contributor to the environmental impact of manure management. Our aim was to assess the life cycle environmental consequences and reduction potential of segregating fattening pig urine and feces with an innovative V-belt system and to compare it to conventional liquid manure management, that is, the reference. Moreover, we aimed at analyzing the uncertainty of the outcomes related to applied emission factors. We compared a reference with two scenarios: segregation with solid, aerobically, stored feces and with liquid, anaerobically, stored feces. Results showed that, compared to the reference, segregation reduced climate change (CC) up to 82%, due to lower methane emission, reduced terrestrial acidification (TA) and particulate matter formation (PMF) up to 49%, through lower ammonia emission, but increased marine eutrophication up to 11% through nitrogen oxide emission from storage and nitrate leaching after field application. Fossil fuel depletion did not change. Segregation with liquid feces revealed lower environmental impact than segregation with solid feces. Uncertainty analysis supported the conclusion that segregating fattening pig urine and feces significantly reduced CC and additionally segregation with liquid feces significantly reduced TA and PMF compared to the reference.

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.