A review of literature concerning odors, ammonia, and dust from broiler production facilities: 2. Flock and house management factors
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Confinement buildings are one of the most likely sources of odor an a broiler operation. The buildings must be ventilated, either mechanically with fans or relying on natural airflow, to prevent animal mortality and enhance animal health. Consequently, odors generated within the building are carried to the surrounding environment by the ventilation system. This review addresses the management of those factors that affect the production and removal of odorants in a broiler production operation. Published literature does not specifically discuss odor generation within broiler houses. Several studies deal with ammonia (an odorant gas) or particulate matter (a pollutant thought to carry odorant gases) emissions in broiler houses. These studies are discussed and inferences are made about the generation of odors under similar conditions. Conditions that lead to higher moisture in the litter tend to increase ammonia release, and by inference, more odorant release. Higher litter moisture is presumed to encourage greater microbial degradation of uric acid excreted by the birds into the litter and release more ammonia. Evaporative coolers may produce excess water droplets that fall to the litter rather than evaporate to cool the incoming air. Broiler houses that use misting systems generally have higher moisture content in the litter at the inlet end of the house. Either type of evaporative cooling system may also reduce litter drying rates by increasing humidity levels within the house. At the other extreme, low litter moisture could lead to the production of more particulate matter (i.e., dust), a pollutant that can transport odors to the atmosphere. The optimum litter moisture content that can minimize odorant and dust release is somewhere within the range of 25 to 35%, but exact values for optimum balance depend on numerous house-specific conditions. Changes in dietary nutrient levels can alter the production of ammonia by varying the amount of nitrogen available; however, most currently researched methods show negative impacts on productivity. Management of watering devices is critical to controlling litter moisture. Proper water equipment maintenance and operation are part of daily house management strategies to control litter moisture and, therefore, dust and odor.
