Heat stress
With summer temperatures, swine producers need to be aware of potential breeding and conception problems in swine herds.
Temperatures above 27 C can reduce breeding stock performance. When the respiration rate of a mature sow or boar exceeds 75 breaths per minute, the animal has been heat stressed and breeding performance will likely suffer.
Heat-stressed boars will produce poor quality semen. They will continue to breed normally, but conception rates will be lower, or litter size will be reduced. It takes about five weeks for the male sperm to be produced, so a heat-stressed boar can continue to produce inferior semen for five or six weeks after the stress period.
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
The critical period for the sow appears to be for approximately two weeks after breeding. During this time, the developing embryo must become attached to the walls of the uterus. Another critical period for heat stress is in late gestation. Well insulated and ventilated dry sow barns will normally reduce heat stress for boars and sows.
A drip cooling system over the shoulders of sows in gestation crates or a mist spray system could be used to help cool sows and boars. Drip cooling on sows in farrowing crates will help them maintain their appetite to sustain milk production.
Ensure adequate clean fresh water is available at all times to pigs.
The use of artificial insemination in your breeding program can eliminate many problems associated with poor boar performance because of heat stress or other health problems.
Feeder pig performance can also fall when the temperature tops 27 C. Spray cooling helps to promote better manuring habits and improved market pig performance. A coarse spray is directed on the pig periodically, at a rate of about .45 litres/hog/hour. The heat necessary to evaporate the water from the pig’s body surface comes from the body of the pig, thus cooling it.
In biotech type shelters, maintain 12 sq. feet of space per pig to avoid overcrowding. Increasing water supply by installing extra water nipples for summer consumption in outdoor shelters will help keep feeder pigs cool and maintain feed intake.
For conventional barns, be sure your ventilation system is sized properly and working well for maximum cooling effect.
– Manitoba Agriculture
