2024-02-15 07:31:43
Environmental quality is considered an important risk factor within pig farms. – Article published in the February issue of Suis.
Fabrega, Emma; Bagaria, Marc; Ochoteco-Asensio, Juan; Moreno, Miguel; Burgos, Laura; Cerrillo, Miriam; Good morning, August
Animal Welfare Program, Institute of Agricultural Research and Technology (IRTA), Monells (Girona)
Sustainability Program in Biosystems, Institute of Agro-Food Research and Technology (IRTA), Caldes de Montbui (Barcelona)
The environmental quality within pig farms is considered an important risk factor for both the development of respiratory pathologies and the development of behavioral problems such as caudophagy. Recently, it has also been related to possible modifications of the intestinal microbiota or immunosuppressive effects. The LIFE-MEGA project was carried out with the objective of testing two new technologies, a dry filter and a wet filter, whose objective was both to reduce gas and particle emissions, and to reduce their levels within the farms. The results obtained so far suggest that the dry filter was more technologically effective, which also resulted in a greater number of improved animal welfare indicators. As for the wet filter, whose technological maturity was lower, it showed a less consistent effect, suggesting that some aspects of its operation still need to be improved.
Keywords: environmental quality, animal welfare, dry filter, wet filter.
New technologies to improve environmental quality and animal welfare
Air quality inside pig barns are described as a risk factor for the development of respiratory problems, as well as to impact on abnormal behaviours like tail biting. More recently, air quality has been linked to modifications in gut microbiota and impairments in the immunological response. The LIFE-MEGA project had the objective of evaluating the performance of two new technologies (dry scrubber and wet scrubber), in terms of their capacity to reduce both emissions of gases and particle matter as well as levels inside the farms. The results obtained up to now indicate that the dry scrubber presented a better technological performance, and this resulted as well in higher improvements in some animal welfare indicators. With regards to the wet scrubber, with an initial lower technological readiness, more system adjustments may be required to obtain a higher impact on animal welfare.
Keywords: air quality, animal welfare, dry scrubber, wet scrubber.
Introduction
The concept of animal welfare has evolved over time, from the theoretical framework of the “Five Freedoms” established by the Brambell Committee in 1965, to the most current model known as the five domains (Mellor et al., 2020). According to this model, four physical domains are established (nutrition, environment, health and behavior), which impact a fifth domain (the mental and/or emotional state), and this fifth domain, as a result of the impact of the others, represents the global state. of animal welfare. Therefore, there is agreement that the animal welfare of an individual is a dynamic process, to which both positive and negative states contribute. This approach coincides with a classic definition of animal well-being as the result of an individual’s adaptation to the conditions to which he is subject (Broom, 1988), conditioned by his capacity to respond and leading to a state that he perceives as positive. This ability to respond or adapt to changing or new conditions is carried out fundamentally through the physiological stress response. If pigs are not able to respond adequately or stressful conditions last over time, the effects on animal welfare can be noticeable.
One of the productive conditions that subject pigs to the need to adapt is the quality of the air inside the buildings, since, depending on parameters such as density or climatic conditions, levels of gases such as ammonia (NH3) can be recorded. ) or methane (CH4) and suspended particles that can negatively affect both the health and well-being of pigs.
The objective of the European LIFE-MEGA Project was to evaluate the effectiveness of two technologies (dry filter and wet filter) in their capacity to reduce both emissions of ammonia, carbon dioxide and particles into the atmosphere, as well as the levels inside farms, with the aim of reducing the environmental impact and improving the health and well-being of the pigs. The study was carried out in transition farms in Spain and fattening farms in Italy, but this article will focus primarily on the results during the transition.
Environmental quality: effects of ammonia, carbon dioxide and suspended particles
Ammonia (NH3) emissions are derived primarily from the enzymatic breakdown of urea in urine. Additionally, the breakdown of secondary protein metabolites and bedding materials can increase emissions. Ammonia, when released into the environment, causes soil acidification, nitrogen enrichment of ecosystems, as well as terrestrial and aquatic eutrophication. Furthermore, ammonia is a chemically active gas and in the atmosphere it can produce N2O or react with sulfuric and nitric acid to form secondary inorganic particles with diameters less than 2.5 μm (PM 2.5). Continued exposure to certain concentrations of NH3 causes effects on both health and productive efficiency and well-being. It has been described that ammonia in concentrations greater than 35 ppm induces inflammatory changes in the respiratory mucosa and that there is a correlation between NH3 (levels greater than 24.6 ppm) and pleuritis (Donham, 2000) or the development of respiratory infections. (Michiels et al., 2015). More recently, other negative effects of ammonia on multiple organs such as the spleen, liver, jejunum and heart have also been described. When gaseous NH3 enters the blood circulation, it can cause alterations in oxidative stress responses (Kim et al., 2019). NH3 can also alter the expression of inflammation markers and the diversity of the intestinal microbiota (Yutao et al., 2021), in addition to altering components of the immune response such as complement C3, C4, immunoglobulin M or cytokines, resulting in in reduced immune function (Yu et al., 2020) or altered tissue inflammatory status (An et al., 2019). Wathes et al. (2000) described ammonia as a gas capable of inducing aversive behaviors in pigs, including tail biting. Both these authors and Scollo et al. (2016) have described it as one of the notable risk factors for caudophagy. It has also been shown that elevated ammonia levels can have adverse effects on worker health, with published data indicating that at least 25% of workers subject to prolonged exposure are at increased risk of respiratory illnesses. such as bronchitis, mucosal irritation or asthmatic syndromes. For the comfort of farm staff and animals, it is recommended that NH3 levels be kept below 25 ppm and preferably below 10 ppm. (Michiels et al., 2015).
On the other hand, CO2 is a gas with somewhat less harmful effects than ammonia but that can also affect health and well-being, and, in addition, its accumulation reduces the pH of ammonia release. The main sources of CO2 production are animal respiration and release from manure. Furthermore, CO2 concentrations are a useful tool to check whether ventilation rates within houses are adequate (Philippe and Nicks, 2015). Vitali et al. (2021) found that higher levels of CO2 were associated with a higher percentage of ear bites. In addition, high CO2 levels due to inadequate ventilation are usually associated with an incorrect temperature and this can impact other aspects of behavior, such as an increase in dirt on the animals’ bodies because the thermoregulation mechanism they use is changes, and they lie down in the functional defecation area instead of in the rest area, or an increase in the behavior of resting sitting instead of lying down is observed.
Suspended matter particles (PM) are also present in relevant quantities inside pig farms, coming from different sources such as the type of feed and its method of administration or body waste from the pigs themselves (hair, skin, faeces). Inside production buildings, the ventilation rate, density, air distribution and animal activity can influence PM concentration, suspending or resuspending the particles. The risk of suffering from certain respiratory pathologies in pigs, such as pleuritis or pneumonia, is greater when the level of PM10 has increased (Michiels et al., 2015), also reducing the weight gain of the pigs.
For this reason, the new Spanish animal welfare regulations (RD 2023/6083) establish that NH3 and CO2 levels must be regularly monitored and must remain below 20 ppm and 3,000 ppm, respectively, or corrective measures must be taken.
This article appears in issue 204 (January-February 2024) of Suis. Subscribe here to have full access to this and other magazine content.
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