Managing the impact of heat stress in swine production
Pigs have a difficult time dissipating body heat, especially during warmer weather, and heat stress can negatively influence pig performance. When pigs are under heat stress, they voluntarily decrease feed intake to lower their metabolic heat production to maintain a constant body temperature. This reduction of feed intake is considered the pig’s main adaptation to reduce heat production. Additionally, heat stress has been shown to compromise the pig’s intestinal barrier function resulting in increased gut wall permeability, or “leaky gut.” Heat stress impacts pigs of all ages, but the effects become more pronounced in older, heavier pigs due to their lower optimum temperatures. Thus, sows, boars and finishing pigs are more affected by heat stress.
Economically, heat stress is a major cause of swine production losses, with an estimated negative economic impact of nearly $1 billion per year in the United States. Heat stress-related economic losses result from increased morbidity and mortality, suboptimal growth, inconsistent market weights, poor sow performance, and decreased carcass value.
As we prepare for the warmer weather ahead of us, here are some strategies to help reduce the negative impacts of heat stress on pigs (see Table 1 for specific recommendations):
Water supply: Water consumption patterns change under heat stress. During heat stress, overall water intake increases with peak water intakes between 8 to 9 a.m. and between 5 to 8 p.m., as opposed to a single peak during the middle of the day under temperate conditions. During heat stress, a large portion of the drinking water is used to dissipate heat through evaporative heat loss from respiration.
Indirect cooling (cool cells): As outside air enters the cool cell, evaporating water removes a substantial amount of heat from the environment. This causes the exiting air temperature to decrease and humidity to increase. For cool cells to function properly, they must be entirely wet while in operation and waterlines feeding cool cells need to be unplugged. Make sure the pad doesn’t have any air leaks.
Direct cooling (sprinkler systems): Sprinkler systems remove heat from the pig through evaporation and convection. In group settings, sprinkling water in short intervals (about 20 to 30 minutes) allows the humidity to evaporate off pigs’ skin. In addition, larger droplets are preferred as opposed to fogging because fogging can increase humidity in the barn and reduce evaporative heat loss. Sprinkler systems need to be checked frequently to ensure they work properly.
Ventilation: Elevated air speed is essential to decrease heat stress, thus, providing supplemental fans is advised in warm conditions. Air exchange rates in mechanically ventilated buildings should be increased during hot weather to increase the removal of heat and humidity.
Floor space changes: Increasing floor space per pig improves pigs’ ability to dissipate heat, and it becomes especially important with older, heavier pigs.
Nutritional interventions: Some nutritional strategies can also reduce heat stress. These include:
- Reducing high fiber ingredients. The caloric density of fiber is low, and fiber digestion leads to higher heat production.
- Reducing dietary crude protein. Crystalline amino acids can reduce heat production and have been proven to partially reduce the effects of heat stress.
- Supplementing zinc may improve intestinal integrity during severe heat stress in growing pigs.
- Increasing the energy density of the diet with supplemental fat is an effective strategy to increase caloric intake and reduce the amount of heat generated during digestion.
As the summer months approach, pork producers can be proactive and use many of these strategies to help reduce the negative impacts of heat stress on their pigs. Contact a Vita Plus consultant if you need help implementing these strategies in your swine operation.
About the author: Dr. Jose Soto grew up in Chile, where he received undergraduate and graduate training in agricultural sciences and agricultural economics, respectively. He moved to the United States in 2007 and worked for three of the top 10 swine integrators and allied industry, where he was involved with research and development, technical services, and production operations. Most recently, he earned his Ph.D. in animal sciences, with an emphasis on swine nutrition and production management, from Kansas State University. Soto joined Vita Plus as the director of swine nutrition and product development in January 2018.