Atrophic rhinitis: the influence of the aerial environment

Microbiological air quality in free-farrowing housing systems for sows

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Farrowing systems without confinement do not impair microbiological air quality.

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Single loose-housing system proved to be hygienically advantageous.

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Ventilation and hygiene routines can be kept when changing to free-farrowing systems.

This study investigates air hygienic characteristics of housing systems without fixation for lactating sows, with a focus on microbiological air quality. For animal welfare considerations, free-farrowing systems have been developed to replace those with farrowing crates (FC) and are currently available on the market. A group housing system (GH) for six lactating sows, a single loose-housing system (LH), and a conventional system with FC were tested. By maintaining similar management conditions, microbiological air quality was examined in eight batches with 148 farrowings in total with samplings at the beginning, in the middle, and at the end of the occupancy period of 33 days. No significant differences between the systems were observed in the concentration of total airborne bacteria (TAB), haemolytic streptococci (HS), molds, or yeasts. However, the concentrations of TAB and HS increased significantly over time. Additionally, significant correlations were detected for LH and FC between TAB and HS, and between TAB and carbon dioxide; significant correlations between TAB and inside temperature and total animal weight were revealed only in GH. Significant correlations between TAB and both the dust and inside humidity parameters were found only in FC. Given these results, it was shown that the free-farrowing systems used here do not necessarily lead to poorer microbiological air quality.

Engineering choices into animal environments

The means by which choice can be engineered into farm animal environments are described, focusing upon intensive systems of husbandry where choices are the most limited. Choice is assumed to be both necessary and desirable.

The principal components of choice are: (i) environmental choice; (ii) nutritional choice; and (iii) social choice. The management of herds rather than individuals and the persistent trend towards increased intensification generally reduces the opportunities for animals to exercise their environmental and social choices. However, extensive systems can also restrict choice and provide an environment that may, in some cases, be equally barren.

Several common problems may make the provision of choice difficult, including variability and precision of individual choices and the conflicts between the interests of individual animals (as distinct from groups) and farmers themselves.

The availability of choice can be improved by modifying existing systems or developing new systems of livestock husbandry. The choice of physical environments may be made by self selection by an individual animal in a heterogeneous environment; active animal control of an environmental modifier, or automatic control with continual monitoring of physiological and behavioural states. The enrichment of barren environments could also embrace artificial stimulation of the senses. Improving the choice of space for its many social and other uses is likely to be difficult given the financial constraints of livestock husbandry. There are few technical difficulties to improving nutritional choices available to livestock, e.g. automated feeding systems which provide multiple rations.

Production responses of weaned pigs after chronic exposure to airborne dust and ammonia

Nine hundred and sixty weaned pigs were exposed for 5·5 weeks to controlled concentrations of airborne dust and ammonia in a single, multi-factorial experiment. Production and health responses were measured but only the former are reported here. The treatments were a dust concentration of either 1·2, 2·7, 5·1 or 9·9 mg/m3(inhalable fraction) and an ammonia concentration of either 0·6, 10·0, 18·8 or 37·0 p. p. m., which are representative of commercial conditions. The experiment was carried out over 2·5 years and pigs were used in eight batches, each comprising five lots of 24 pigs. Each treatment combination was replicated once and an additional control lot (nominally ≈ 0 mg/m3dust and ≈ 0 p. p. m. ammonia) was included in each batch to provide a baseline. The dust concentration was common across the other four lots in each batch in which all four ammonia concentrations were used; thus the split-plot design was more sensitive to the effects of ammonia than dust.

The pigs were kept separately in five rooms in a purpose-built facility. The pollutants were injected continuously into the air supply. Ammonia was supplied from a pressurized cylinder and its concentration was measured with an NOxchemiluminescent gas analyser after catalytic conversion. The endogenous dust in each room was supplemented by an artificial dust, which was manufactured from food, barley straw and faeces, mixed by weight in the proportions 0·5: 0·1: 0·4. The ingredients were oven-dried, milled and mixed and this artificial dust was then resuspended in the supply air. Dust concentration was monitored continuously with a tribo-electric sensor and measured continually with an aerodynamic particle sizer and gravimetric samplers.

Live weight per pig and cumulative food intake per pen of 12 pigs were measured after 5·5 weeks of exposure. Exposure to both aerial pollutants depressed live weight relative to the control (control v. pollutant, 25·7 v. 25·0 (s.e.d. = 0·33) kg, P = 0·043) and there was a trend for food intake to be lower for pollutant-exposed pigs (control v. pollutant 292 v. 280 (s.e.d. = 7·1) kg per pen, P = 0·124). The reduction in live weight and food intake was dependent upon the concentration of dust (mean across all ammonia concentrations for increasing dust concentration; live weight 25·3, 26·4, 24·0 and 24·5 (s.e.d. = 0·65) kg, P = 0·081; food intake 295, 316, 248 and 263 (s.e.d. = 14·3) kg per pen, P = 0·016) but not ammonia (mean across all dust concentrations for increasing ammonia concentration; live weight 24·4, 25·1, 25·3 and 25·3 (s.e.d. = 0·41) kg, P = 0·158; food intake 279, 275, 288 and 279 kg (s.e.d. = 9·0) kg per pen, P = 0·520). There was an interaction between dust and ammonia for live weight (P = 0·030) but the effects were complicated and may have been the result of a type I error. There was no interaction for food intake (P = 0·210). In general, both food intake and live-weight gain, but not food conversion efficiency, were lower for weaned pigs exposed to 5·1 and 9·9 mg/m3dust concentrations compared with 1·2 and 2·7 mg/m3treatments. Other measures of production were also analysed and supported the overall interpretation that dust concentrations of 5·1 mg/m3and higher depress performance.

This study is the first to quantify the effects of chronic exposure to common aerial pollutants on the performance of weaned pigs. The results suggest that dust concentrations of 5·1 or 9·9 mg/m3(inhalable fraction) across ammonia concentrations up to 37 p.p.m. adversely affect performance. The commercial significance of these findings depends on the financial benefits of the superior production at low dust concentrations relative to the cost of providing air of this quality.

Under what conditions is it possible to produce pigs without using antimicrobials?

Antimicrobials are commonly used in pig production to control bacterial infections. However, there is increasing pressure from supermarkets and consumers and other sectors to reduce or eliminate the use of antimicrobials in animal agriculture. Banning the use of antimicrobials in some countries has led to increased disease and welfare problems, so it is important to know under what conditions pigs can be produced without the use of antimicrobials. In this review, practices that can prevent disease, and therefore reduce the need for antimicrobials were researched from published experimental challenge trials, field studies and risk factor analyses. Disease prevention practices were examined from pathogen survival and transmission studies, vaccine and disinfectant efficacy studies and nutrition trials. From these studies we collated the important practices that manage or prevent disease and improve pig health. We also reviewed new diagnostic assays and technologies to better monitor the pig and its environment at the herd level. Many of the conditions necessary to produce pigs without antimicrobials have been known and understood for a long time. The application of high standards of biosecurity and hygiene is crucial for creating the conditions for reduction of antimicrobial use. Factors important in preventing disease include eradication or elimination of pathogens, minimising mixing of pigs, cleaning and disinfection of pens and sheds, ventilation to improve air quality, reducing stocking density and eliminating potential vectors of disease. Improving the health of pigs also relies on vaccination and improved consistency of nutrition. The development of diagnostic technologies that correlate with disease and production will enable the detection of potential disease problems at the individual or herd level before disease outbreaks occur and before antimicrobials are needed. The development of vaccination technologies for prevention of disease and diagnostic technologies that can be used on-farm to predict disease outbreaks are integral to safely moving towards antimicrobial-free pork. Pig production without the use of antimicrobials is not simply a matter of substituting conventional antimicrobials with alternative antimicrobial substances and expecting the same result. Any move to antimicrobial-free production requires an acknowledgement that pig production costs may increase and that many pig production practices must change. Such changes must also ensure that animal welfare and food safety and quality standards are maintained or improved, and that reliable markets for the product are found. This paper does not seek to argue the science or opinion of reasons behind the desire to reduce antimicrobial use in animal agriculture, but rather discuss the circumstances under which reduction or elimination of antimicrobial use in pig production is possible.

SAZONALIDADE DA AMBIÊNCIA TÉRMICA, AÉREA E ACÚSTICA EM CRECHE E TERMINAÇÃO DE SUÍNOS

A tipologia do alojamento de suínos é dependente do clima externo regional e local, enquanto avariação devido às estações do ano interfere no estresse térmico sofrido pelos animais. O objetivodesse trabalho foi avaliar a influência do horário do dia, bem como das estações do ano, noambiente interno de alojamento de suínos em creche e terminação, em clima subtropical. Oexperimento foi conduzido em uma granja comercial de produção e foram registrados dados detemperatura de bulbo seco (TBS), umidade relativo do ar (UR), temperatura de globo negro (TGN),concentração de amônia e níveis de ruídos, no centro geométrico do local a uma altura de 1,5 mdo piso, em seis horários diferentes, por dois anos consecutivos. Os resultados mostraram que asvariáveis ambientais estudadas (TBS e TGN) foram influenciadas pela estação do ano e pelohorário do dia. As concentrações de amônia obtidas oscilaram durante o dia, sendo que os maioresvalores foram encontrados no período da tarde. Os níveis de ruído na instalação de creche nãoforam influenciados pela estação do ano, entretanto, foram influenciados pelo horário do dia.

Effect of aluminum chloride and dietary phytase on relative ammonia losses from swine manure

Ammonia (NH3) losses from swine manure contribute to odor problems, decrease animal productivity, and increase the risk of acid rain deposition. This study was conducted to determine whether aluminum chloride (AlCl3) or dietary manipulation with phytase could decrease relative NH3 losses from swine manure. Twenty-four pens of nursery pigs were used in two trials, and the pigs were fed normal or phytase-supplemented (500 IU/kg) diets. Aluminum chloride was added to manure pits (1.9 x 1.2 x 0.5 m) under each pen at 0, 0.25, 0.50, or 0.75% (vol:vol) of final manure volume. Manure pH and NH3 losses (measured by relative NH3 flux) were determined twice weekly. The addition of AlCl3 at 0.75% decreased (P < 0.05) manure pH from 7.48 to 6.69. Phytase decreased (P < 0.05) manure pH to 7.07 compared with 7.12 in the normal diet manure. Aluminum chloride administered at 0.75% without phytase reduced (P < 0.05) relative NH3 losses 52% for the entire 6-wk period. Relative NH3 losses were decreased (P < 0.05) from 109 mg of NH3/(m2 x h) in pens containing pigs fed the normal diet without AlCl3 to 81 mg of NH3/(m2 x h) in pens housing pigs administered the phytase diet, a 26% reduction. When the phytase diet and 0.75% AlCl3 additions were used in combination, relative NH3 losses were reduced (P < 0.05) by 60% compared with pens of pigs fed the control diet without AlCl3. Decreases in manure pH were likely responsible for the observed reduction in NH3 losses. Multiple regression was performed with relative rates of NH3 losses as the dependent variable and rate of AlCl3 addition, diet, and manure pH as independent variables. The model was tested using a stepwise regression (P < 0.001), and results indicated that the most important factors determining NH3 losses were manure pH and diet. However, the contribution of AlCl3 cannot be discounted. When manure pH was regressed against AlCl3 and dietary phytase, AlCl3 levels accounted for 64% of the variation in manure pH (P < 0.001). Dietary manipulation with phytase and application of AlCl3 to manure are promising management practices for the reduction of NH3 from swine facilities.

Lack of effect of aerial ammonia on atrophic rhinitis and pneumonia induced by Mycoplasma hyopneumoniae and toxigenic Pasteurella multocida

The objective of this experimental study was to determine the effects of aerial ammonia on disease development and bacterial colonization in weaned pigs inoculated with toxigenic Pasteurella multocida and Mycoplasma hyopneumoniae. Two groups of 10 pigs each were continuously exposed to 50 and 100 p.p.m. ammonia, respectively, and compared to a non-exposed control group of 20 pigs. Following aerosol inoculation with M. hyopneumoniae at day 9, all pigs were aerosol-inoculated with toxigenic P. multocida type A at days 28, 42 and 56. At day 63 they were euthanized. Clinical signs including coughing and respiratory distress were present in all groups following inoculation. No significant differences could be established in the extent or frequency of pneumonia between ammonia-exposed pigs and controls, or in the extent of conchal atrophy, the frequency of isolation of toxigenic P. multocida from conchae, tonsils, lungs and kidneys, or the average daily weight gain. The recovery of toxigenic P. multocida from nasal swabs following inoculation was significantly greater in pigs exposed to 50 p.p.m. ammonia or more as compared to the control group. In conclusion, high levels of ammonia combined with inoculations with M. hyopneumoniae and toxigenic P. multocida had no significant effect on disease development, but may have enhanced colonization by toxigenic P. multocida on the nasal turbinates.

Epidemiological investigation of the influence of environmental risk factors on respiratory diseases in swine--a literature review

The influence of environmental and management factors on respiratory diseases in pigs is reviewed from an epidemiological point of view. The suitability of methods for the investigation of risk factors is discussed including aspects of study design, case definition, exposure assessment and data analysis. The results of published studies suggest a causal web of factor interaction, the analysis of which provides considerable challenges for current epidemiological techniques. New approaches to the problem should be further explored in the future in order to provide reliable advice to decision makers.

The role of infectious aerosols in disease transmission in pigs

Airborne transmission is of significance for a number of infectious diseases in pigs. The general principles of the airborne pathway, including aerosol production, decay and inhalation, are reviewed. Practical issues regarding aerosol sampling and sample analysis are also discussed. Details of the aerobiology of porcine diseases, including foot-and-mouth disease, Aujesky's disease, and respiratory diseases, are explained. Some additional, potentially airborne diseases are discussed in terms of the evidence for their aerosol transmission. In order to prevent airborne diseases in pigs, dust reduction, air filtration, air disinfection, vaccination and the establishment of disease-free regions could be considered.

Concentrations and emission rates of aerial ammonia, nitrous oxide, methane, carbon dioxide, dust and endotoxin in UK broiler and layer houses

1. A survey of the concentration and emission rates of aerial ammonia, nitrous oxide, methane, carbon dioxide, dust and endotoxin was undertaken in 4 examples each of typical UK broiler, cage and perchery houses over 24 h during winter and summer. 2. Overall the air quality within the poultry houses was unsatisfactory as judged by the dual criteria of farmer health and bird performance. 3. Mean concentrations of ammonia ranged from 12.3 to 24.2 ppm while concentrations of methane and nitrous oxide were close to ambient levels. Mass concentrations of aerial dust ranged from 2 to 10 mg/m3 and 0.3 to 1.2 mg/m3 for inspirable and respirable fractions respectively, while endotoxin concentration was typically about 0.1 microgram/m3 (inspirable fraction). 4. Emission rates of gaseous ammonia were rapid (9.2 g (NH3)/h per 500 kg live body weight) and uniform across the three types of building, while emissions of methane and nitrous oxide were slow. Rates of dust emission ranged from 0.86 to 8.24 g/h per 500 kg live body weight in the inspirable size fraction.

A morphometric and functional study of the toxicity of atmospheric ammonia in the extrathoracic airways in pigs

The effects of atmospheric ammonia (NH3) on the nasal and tracheal mucosa of pigs were investigated by morphometric and functional methods. Pigs were exposed to four concentrations of NH3 [5 (control), 25, 50 and 100 ppm] for 6 days in a specially designed air-pollutant exposure chamber. Samples were taken from the turbinates and the trachea, and the respiratory mucosa was examined by light and scanning electron microscopy. Dose-response curves to carbachol and isoproterenol were constructed using isolated strips of tracheal smooth muscle, with or without epithelium. In pigs exposed to ammonia, considerable mucosal injuries were observed in the turbinates but not in the trachea. The number of neutrophils in the epithelial layer and in the lamina propria, and epithelial hyperplasia were closely and significantly correlated with the concentrations of ammonia (r = 0.894, p < 0.001; r = 0.727, P < 0.001; and r = 0.818, p < 0.001, respectively). Except for the lamina propria, all these changes were significant (p < 0.05) at ammonia concentrations as low as 25 ppm. The percentage of the surface of the turbinate mucosa that was ciliated tended to decrease with increasing ammonia concentration (r = 0.439, p < 0.082). Ammonia induced smooth-muscle hyperresponsiveness to carbachol with a close linear correlation between individual values of the carbachol-induced maximal effect and the NH3 concentrations (r = 0.526, p < 0.003). While mechanical destruction of the epithelium induced an increase in Emax in the control group, no difference was observed between the intact and denuded strips from animals exposed to ammonia. The response to isoproterenol was not influenced by ammonia. It was concluded that quantitative histological analysis of the inflammatory infiltration and epithelial hyperplasia in the turbinates is a useful tool for quantifying the effects of atmospheric pollutants in pigs; a 6-day exposure to ammonia induces nasal irritation and functional disturbances of the tracheal smooth-muscle contractions at concentrations as low as 25 ppm.