Tuesday, January 13, 2015

What is water conservation worth? Swine edition

As we strive for sustainability, water conservation is an important industry, with agriculture and animal production being no expectation. Besides being environmentally responsible, reducing the amount of water wasted in a barn has several positive benefits. First, and most importantly, every gallon that ends up in the manure has to be land applied, and depending on your application rate and distance to cropland this can cost upwards of $0.01-0.02 per gallon with an additional charge of around $0.001 per gallon per mile hauled beyond the first mile. Reducing water wastage also reduces the required manure storage capacity and expenses related to pumping and purchasing water.

Water is used for three main purposes in swine production: animal drinking, animal cooling, and facility/equipment washing. It is estimated that at a swine finishing site, the average whole farm consumption of water will be around 1.5 gallons per pig per day. Of this about 7% of the water is from facility washing, 12% from animal cooling, and 80% from animal drinking, with the remaining 1% from domestic uses which includes drinking, hand/boot washing, laundry, and showering. To put this into perspective, it is estimated that the average American uses 80-100 gallons of water per day in their home!

As animal water consumption accounts for the greater amount of water use, a large emphasis has been placed on the impact different drinkers have on water use. Examples of different drinkers include nipple drinker, cup drinkers, and wet/dry feeders. In each case there are many styles of each of these drinker types, but for classification purposes I’m calling: (1) a nipple drinker any drinking device that allows water not consumed by the pig during drinking to flow directly into the manure storage; (2) cup drinkers any animal drinking system that provides a cup or bowl for pigs to drink from and are filled by a pig actuated lever or nipple or a water level activated float level; and (3) wet/dry feeders to be a feeding/drinking system that mixes the dry feed and water into the same bowl, tray, or trough. Example of each of these types are shown in the pictures below.

A solid mounted nipple drinker and close-up of the nipple drinker.

A nipple square bowl with standard mouthpiece and a shallow cup drinker.

A shelf style wet/dry feeder and wet/dry feeder.

Research has tended to indicate that as you switch from dry feeders and nipple drinkers to dry feeders and cup drinkers or wet-dry feeders, water consumption decreases. This intuitively makes some sense as by design, cup/bowl drinkers should decrease water wastage as water related from the lever falls into the cup for the pig to drink. Similarly, wet/dry feeders are designed to catch any water from the nipple and offer the ability for it to mix with the feed.
Building Type
Whole site
water usage
(gal/pig space-day)
Animal Drinking Consumption
(gal/pig space-day)
Other water
(gal/pigs pace-day)
Finisher, dry feed/nipple
2.33 (0.32)
Finisher, dry feed/cup
1.15 (0.17)
Finisher, wet/dry
1.25 (0.33)

Water is used to wash swine facilities before a new group of pigs is placed. In general little literature is available on water consumption during barn washing. However, a study by Hurnik (2005) did compare several different techniques including hot and cold water, soap usage, and pre-soaking the facility. They found that using hot water reduced washing time by about 22%, using soap reduced washing time by 8%, and pre-soaking could reduce washing time by up to 50%. Unfortunately, no water consumption values or pre-soak times were reported for the different treatment. However, an industry survey indicated that on average about 3 gallons per pig space per wash were used in power washing the barn. General practice is to pre-soaking the facility before washing and this appears to increase water consumption to about 7 gallons per pig space to wash.

So let’s see if we can put some numbers on this, if you were to switch from a nipple drinker to a cup drinker. Assuming that pigs are still getting all the water they need, since it is offered ad lib, then any difference in water consumption is directly proportional to the amount of slurry being produced. In this case, the change would result in a reduction 0.87 gallons per pig space per day (1.87 gal/pig space-day – 1.00 gal/pig space-day), or about 300 gallons per pig space, per year. Which would result in a saving of about $4.50 per pig space per year in manure application costs. In addition to the reduction in cost from manure application, if you are using rural water  there is also a cost of getting your water (Polk County Rural Water District #1 is charging $4.00/1,000 gallons). This means saving 300 gallons would reduce costs by about $1.20 per pig space per year, for a total savings of $5.70 per pig space per year. This compared to an estimated cost of about $2.50-4.50 per pig space to switch to cup or bowl drinkers.