Water conservation is important in any industry and swine production is no exception. Many water conservation technologies and practices are currently used in swine production, but not universally. The goal of this paper was to provide an in-depth review of water usage and conservation technology and practices currently employed by the swine industry, to investigate the conservation measure’s effectiveness and cost efficiency, and to research water conservation technology and practices from other industries that may be applicable to the swine industry. This goal was accomplished via a thorough review of published literature, university extension and commodity group publications and fact sheets, and interviews with industry professionals and workers. A survey of swine producers representing 319 swine production facilities was conducted to collect water use and manure slurry production values as well as pig drinker types and facility washing and cooling practices. The collected data was organized by facility and water use technology and practice in order to analyze the effect of the various water management and conservation practices employed.
Swine production consists of two main phases: gestation/farrowing, and swine finishing. Some swine producers use an additional nursery phase between these two main phases but in terms of water use, gestation/farrowing and finishing are responsible for most of the water used in swine production. Swine finishing in the United States uses 62.2% of an estimated 41.3 billion gallons of water annually for all of swine production while gestation/farrowing and nurseries use the remaining 33.4% and 4.4% respectively. Through the literature review and producer survey it was found that animal drinking consumption was approximately 80% of total water usage. For these reasons, the most total reduction in water use could be realized through water conservation technologies and practices applied to finishing swine drinking systems.
Water is used for three main purposes in swine production: animal drinking, animal cooling, and facility/equipment washing. Water usage and conservation technologies and practices for each of these phases were investigated. Water cooling practices were reviewed and analyzed. It was found that if recommended cooling rates were used, cooling water usage could represent approximately 10% of total site water usage. However, in a survey of 144 Iowa swine producers, only 50% reported using water cooling systems. Swine facility and equipment washing water usage were obtained and analyzed primarily from the producer survey and found to account for 5-10% of total site water usage. There was some variability found in water used by different power washer performance ratings and facility presoak schemes. Use of an intermittent pre-wash facility soaking scheme versus a continuous soak was found to use about half the water without affecting total wash time. Water conservation technologies and practices from other industries such as washing and maintenance techniques as well as rain water capture were evaluated for applicability to swine production. In an analysis of rainwater capture for three areas of the United States it was found that monthly rainwater capture from the roof of a facility could account for 5-25% of monthly water requirements for that facility.
Technology and practices found to be the most effective were analyzed for cost efficiency. An analysis of leaking pig drinking water delivery systems showed how cost effective proper maintenance can be. If 25% of the drinkers in a 1000 head swine finishing facility leak at the rate of one drip per second, 43,800 gallons of water will be added to the manure storage. At a manure slurry handling cost of $0.012/gallon, that represents a cost of $525.60 to land apply the leaked water as manure slurry. A producer could spend approximately $26/leaking nipple to repair the leaks in this barn to equal the extra amount that would be spent on land applying that water as part of the manure slurry.
Collected data confirmed that pig drinker type and management significantly affected both water disappearance from drinkers and total facility water use. If it is assumed pigs in the same production phase consume similar amounts of water, the difference in water disappearance and total site water use between similar sites could be attributed to water wasted. Wasted water dilutes the nutrient density of the manure slurry and increases the amount of slurry to be handled, which increases operating costs. The literature review and producer survey revealed pig drinker selection and management could reduce water usage by up to 30%. Intense management of nipple drinker height and flow rate, cup drinkers, and wet/dry feeding systems was shown to reduce water wastage considerably. Using a manure slurry application rate of $0.012/gallon it was found that savings of approximately $2.00/pig space/year could be realized in reducing water usage by 25% while pig drinkers range in cost from less than $1 to $10/pig space to employ. Depending on the lifespan and amount of water saved by the drinker, it could be extremely cost efficient to use water conserving drinkers or management practices. Not only is water conservation in swine production environmentally responsible, it could result in sizable cost savings.