Heat stress in growing pigs can begin at temperatures above 70°F, triggering a chain reaction of reduced feed intake, slower growth, poorer feed efficiency, and increased mortality. Because pigs have very few functional sweat glands, even small increases in temperature can have a big impact on their ability to stay cool. In hot conditions, pigs eat less to reduce internal heat, shifting nutrients away from lean growth and toward fat deposition—resulting in more days to market, greater weight variation, and lower carcass quality.
In the Pipestone, MN area, the National Weather Service reports that from 2023 to 2025 there were about 43.7 days each year with highs above 85°F. When every pig and every pound matter, small things like keeping your pigs cool can make a big impact on performance at market.
Sprinkler Cooling Systems
Sprinkler systems are widely used and highly effective when managed correctly. They work by intermittently wetting pigs’ skin, allowing evaporation to pull heat from the body. Recommended management guidelines:
- ON: run sprinklers for 2 to 4 minutes (until pigs get wet).
- OFF: allow pigs and pen surfaces to dry completely:
- 15–20 minutes in dry conditions.
- 45–60 minutes in humid conditions.
- Proper ON/OFF cycling is critical for effectiveness.
- Use on healthy pigs ≥100 lb.
- Set temperature activation between 80–85°F.
- Limit use to daytime hours (6:00 AM–10:00 PM) when heat stress risk is highest.
Poorly managed systems (running too long or too frequently) reduce cooling efficiency and may increase humidity and animal discomfort. Combining sprinklers with increased air velocity significantly improves cooling efficiency, especially in humid conditions.
Evaporative Cooling Pads (Cool Cells)
Evaporative cooling pads are used in tunnel ventilated barns. Hot outside air passes through a wetted pad, cooling the air before it enters the barn. Key considerations:
- Most effective in low humidity conditions.
- Can reduce incoming air temperature by 6–12°F.
- Proper maintenance is essential:
- Clean and inspect pads regularly for algae, mineral buildup, and debris.
- Ensure uniform water distribution.
- Keep sump tanks clean.
- Allow pads to dry completely at least once daily (overnight) to reduce algae growth and media degradation.
- If using hard water, periodic descaling or filtration is recommended.
Installation and maintenance costs are relatively high, but benefits can be substantial when managed properly. A study conducted in central Iowa estimated 33.4 and 200.4 gallons of water usage per pig on an annual basis for the sprinkler and the evaporative pad systems, respectively.
Management and Nutritional Practices to Support Cooling
Cooling systems work best when combined with good management:
• Handle and move pigs during the coolest parts of the day (early morning or late evening).
• Monitor pigs closely during heat waves for early signs of heat stress.
• Increase dietary energy density to help compensate for reduced feed intake. (Consult your Nutritionist before making diet changes).
