It's a simple fact: Pigs need water. But when it comes to how much, what kind and exactly why, the answers aren't quite so simple.

Phil Thacker, a swine nutritionist at the University of Saskatchewan in Canada, notes that water is critical for five functions in the pig:

  • It helps the animal regulate heat.
  • It helps transport key compounds throughout the pig's body.
  • It's needed for a complex series of chemical reactions in the pig.
  • It lubricates membranes such as in the respiratory system.
  • It protects internal organs, providing sort of a cushion in the pig's body.

Pigs lose water in four ways: via the lungs during respiration, via evaporation from the skin, through feces and through urination.

Evaporation results in little water loss in the pig, but through manure pigs can eliminate more than 5 pounds of water per day.

Thacker also notes that eight factors can effect how much water pigs will need. Any of these in extreme situations can change the quantity of water your animals need.

1. Environmental temperature. Pigs need more to drink when it's hot.

2. Relative humidity. As humidity rises in hot weather, pigs will will require more water.

3. Health. Diarrhea in particular can increase water demands.

4. Feed intake. The more feed a pig eats, the more water it needs. Thacker says a pig generally needs three times as much water as feed.

5. Dietary protein content. High protein levels require more water.

6. Dietary salt. Of course, the more salt your pigs consume, the more water they will want.

7. Water in the diet. If the diet is dry, pigs will need to drink more water to make up for a shortfall in the feed.

8. Water salinity. They'll have to drink more water if their water contains high salt levels.

Thacker's overall point: Don't restrict water. Make sure your pigs have access to all they need. It can help them perform the key biological processes that keep them healthy and let them optimize their growth potential.