How does the air quality of the pig barns affect the pigs?

In modern society, the productivity and efficiency of pigs have greatly improved, but the gas and odor from rearing pigs still exists and has become a serious problem with social impact in many countries. Pig facilities are inherently associated with air pollutants and gas emissions such as ammonia (NH3), hydrogen sulfide (H2S) and carbon dioxide (CO2). These gases often negatively impact air quality, animal health, and quality of life in and around these facilities.

Swine production has undergone rapid transformation from family owned operation to a large scale industrial enterprise. Since increasing number of pigs are reared on a large scale in confined buildings, some of the swine barn workers may be employed to work eight hours per day. Swine barn workers suffer from higher incidences of impaired air flow and lung inflammation, which is attributed to high intensity and interrupted exposures to pig barn air. The air in these barns contains gases, dust, microbes and endotoxin with endotoxin being the major suspect as the cause of lung dysfunction. This review attempts to describe the current state of knowledge of incidences and mechanisms of pulmonary dysfunction following exposure to the barn air.

Among these gases, ammonia is one of the most widely recognized because of both its prevalence and distinctive effects on animal well-being and pork production but also for its impact on the environment. Ammonia emission is a natural process produced by the anaerobic decomposition of animal waste; however, chronic exposure can lead to health problems and could subsequently affect animal performance, especially in a confined environment. Research published by Koerkamp et al. (1998) suggested that emissions of NH3 from sows and wean and finishing pigs ranged from 22 to 1,298 mg/h/animal. Additionally, environmental ammonia ranged from 5 to 30 ppm in swine confinements. While highly variable, concentrations over 20 ppm of NH3 can adversely impact the health of both workers and animals.

Where does ammonia come from?

Ammonia is released from the urea present in urine through the activity of waste-degrading microbes. Urea is formed by the kidneys and is utilized by the body to excrete nitrogen, which is essential for normal health.

Several management factors can contribute to poor indoor air quality and, subsequently, higher concentrations of ammonia, including damp bedding, lack of ventilation and nutritional factors, like overfeeding protein.

How does ammonia affect pigs?

Ammonia is a toxic gas that, when present in high concentrations, can easily become a chronic problem in the barn. Other documented effects associated with ammonia include tail-biting and respiratory diseases in pigs, but it can also lead to severe problems in human caretakers and can be detrimental for the environment.

Research conducted by Andreasin et al. (1994) suggested that even minimal exposure to ammonia can be harmful. For example, swine exposed to 50 ppm of ammonia for 20 minutes a day on just four occasions experienced reduced performance and decreased live bodyweight gain (between 37 and 90 kg) (Fig. 1) In addition, ammonia can seriously affect respiratory health and delay puberty, even at the low level of 20 ppm (Malayer et al. 1980).

How does ammonia contribute to pollution?

Ammonia is the major alkaline component of the Earth’s atmosphere and can be found in water, soil and air. Ammonia impacts the environment through several different mechanisms, including by influencing air quality, odor, eutrophication, acidification and direct toxicity and also via indirect effects.

Ammonia pollution has a major impact on biodiversity, with nitrogen accumulation affecting the diversity and composition of plant species within affected habitats. Additionally, atmospheric nitrogen deposition has induced adverse effects in forest systems and eutrophication in several estuarine and coastal ecosystems.

How to reduce ammonia emissions in pig barns

A holistic approach is needed to improve indoor air quality in swine barns, from checking ventilation to providing the proper equipment to implementing nutritional strategies and manure management. Here are three areas to focus on for improving ventilation and reducing poor indoor air quality:

1. Determine that all fans are in working order. Clean fan blades and louvers and ensure that the fan motor and thermostat are in the proper condition.

2. Check that the curtains close securely, that debris and/or equipment are cleaned up and put away before snowfall, and that the propane tanks are examined for leaks.

3. Check air inlets and temperatures and test the supplemental heat sources inside of your buildings.

Additionally, many pork producers and animal Feed Additive operations also utilize nutritional strategies and technologies in their feed, such as reducing the amount of crude protein or including Yucca schidigera (YS) plant extract in the diet, which can be used as an additive to consistently reduce adverse gas and odor emissions and decrease ammonia concentrations. Peer-reviewed data has shown that YS can reduce aerial ammonia levels by up to 50%.

The data from animal and human studies show that barn air can induce lung dysfunction. Recent data from animal studies and from in vitro studies have started to elucidate mechanisms of lung dysfunction induced following exposure to the barn air. However, many questions remain unanswered. One of the central questions relates to precise and relative contributions of various toxic molecules in the barn air to lung dysfunction. The endotoxin is the foremost toxic agent in the barn air. The role of endotoxin in barn air induced lung dysfunction can be assessed through the use of mice that lack a functional Toll-like receptor-4. Second logical experiment is the physical and biochemical characterization of the dust particles in the barn air. Specifically, we need to know if the barn air contains dust particles which are less then 100 nm in size because particles of this size are believed to provoke a vigorous cardiopulmonary response。