This past week I gave 2 presentations that included a discussion of management for summer heat relief to different groups in Iowa and Illinois. At both locations, comments following the presentation reaffirmed what I’ve known for some time – producers and their advisors don’t fully understand how to keep pigs cool in hot weather.

The following bullet points are the basics of summer cooling of pigs:

• Pigs get hot and reduce performance at much lower temperatures than most producers and advisors expect. Recent data suggests that on partial slats, 132 pound pigs begin reducing feed intake when air temperature is 77 F. Consider this in light of the fact than many producers don’t believe in wetting pigs (they might get sick!) or don’t begin wetting until the upper 80’s.
• If stirring fans are used to assist in cooling pigs, they should be aimed so air moves over the pigs – not aimed so the air on the ceiling is moving. If aimed over pigs, they should be connected to a thermostat so they turn off in evening hours. I generally recommend these begin operating at +15 F over the controller set point.
• For curtain sided barns with no stir fans or incorrectly installed stir fans, set the wetting system so it begins operating at +18F above set point.
• For tunnel barns and curtain barns with fans on thermostats, you can begin wetting at 20-22F above the set point. The reason for the delay versus curtain barns is you know a draft is going over the pigs so evaporation will be more effective immediately.
• The ON time for wetting the pigs should not be over 2 minutes. The goal is to wet the pigs and then let them dry. Many producers make the mistake of thinking a longer ON time will be more effective in cooling. The most effective cooling is when pigs are drying during the OFF cycle.
• If you can’t get pigs in the far pens wet without excessive water in the first pens, consider replumbing your dripper/mister lines. Try taking the main feed to the middle of the barn and pressuring the dripper/mister lines in 2 directions. This will allow you to cut your ON time by as much as 50%.
• Begin with a 15 minute OFF time. Rewet the pigs when the cement slats under the pigs begin drying.
• Use large drop emitters or nozzles. Misters are not recommended. They are difficult to keep functioning in areas with poor water quality, and the fine mist is not as effective in wetting the pigs as large droplets. Your goal is wet pigs that dry off, not wet, cool air above the pigs!
• Target nozzle sizes and locations that wet no more than 60% of the pen area.
• In curtain barns consider hollow cone nozzles.
• In tunnel barns, consider flat fan nozzles that are positioned parallel to air flow.
• If the controller has the capability, consider programming it so no wetting of pigs occurs for a 6-8 hour period at night. This allows floors and equipment to dry.