Unintended impacts on animal welfare and environment of combined farm animal housing with manure storage

Manure management starts in the animal barn and progresses through storage, after perhaps some processing, and land application of nutrients. Many modern “barn” designs not only house the animals but also include long-term manure storage. Some examples include: hens in high-rise house; swine or dairy over slatted floor; broilers on built-up ‘litter’. Various reasons have created this scenario, but alternatives exist that benefit the indoor and external environment while maintaining or even enhancing nutrient management. Considering both science and social concerns there is considerable evidence that separately managing animal environment and manure storage has benefit. Studies demonstrate that frequent removal of manure from animal housing improves indoor air quality. Reduced indoor manure-gas levels benefit animal and worker health and can decrease emissions of (potentially) regulated gases and odors from that facility. Once removed from the animal housing the manure can be stored and managed with options that are not available when animals are kept in the same air space. Finally, assuring a healthy environment in which to work and raise animals assists animal agriculture as it continues to address limited antibiotic options and perceptions about animal welfare practices. This article outlines points to consider in facility engineering design related to manure storage and animal housing by providing reflections gathered through research, experiences and observations.