Heat stress problems in swine

Our climate is changing. Periods of heat stress for farm animals will increase in frequency and/or in length. This will - among other things - affect the welfare and production capacity in swine production. Let’s review some problems pigs will run into when they are heat stressed. This article is part of a 3 part series. Also read the first part with facts about heat stress in swine in our news archive and keep an eye out next week for the final part in which we'll detail some support options that can help the animals to cope with periods of heat.

Read 'Facts about heat stress in swine' first >>

The production consequences of heat stress will vary from more days to market due to reduced growth rate to actual loss of animals. Other costs related to heat stress may be harder to measure. Safe to say that none of them are good for you or your animals. Let's take a look at a few well known problems that occur when pigs are heat stressed. 

Problem: heat stress can also result in reduced carcass classification
Heat stress affects metabolic pathways. Lean tissue accretion is limited due to reduced protein synthesis in combination with increased muscle proteolysis to provide energy. The ability to use adipose tissue as an energy source is reduced combined with increased lipogenesis resulting in increased adipose tissue accretion. This results in an unfavorable carcass composition.

Problem: reduction of productivity parameters
Heat stress in sows can result in reduced feed intake, reduced fertility and reduced milk production. Reduced milk production may lead to impaired piglet growth. The reduction in milk production is actually larger than could be expected from the reduction in feed intake alone. The gap is explained by the increased blood flow to the skin leaving less blood to support the processes in the mammary glands resulting in decreased milk production.

Problem: heat stress can have a genetic impact on offspring
Heat stress, especially during first half of gestation, may have an epi-genetic impact on offspring. Piglets exposed to in utero heat stress are born with an increased body core temperature leaving them extra sensitive to heat stress during their life. It has also been shown that later in life (early finishing phase) these pigs have different body compositions, they will have less lean meat accretion and increased adipose tissue accretion.

Problem: heat stress can start a negative spiral of vital physiological functions
When heat stressed animals shunt their blood flow to the skin to increase the radiant heat dissipation, the gastrointestinal blood vessels constrict in order to maintain blood pressure. This means less blood circulating in the gastro-intestinal system to absorb nutrients from the feed and to supply the intestinal cells with nutrients and oxygen which in turn leads to decreased FCR, reduced growth or milk production and eventually also to reduced cell wall integrity and leaky gut, increasing the risk for infections. If the heat stress continues, the increased respiratory rate may lead to respiratory alkalosis, which is lethal if not reversed. The pigs also start to drink excessively leading to a loss of electrolytes via the urine which may result in diarrhea, further increasing the severity of the situation.

Keep an eye on perstorp.com or our Animal Nutrition social media channels the next few weeks as we explore some of the support options that can help the animals to cope with periods of heat.

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Part 3: Support options for pigs experiencing heat stress >>