The effect of temperature on sow performance

piglets and sow

Keep them cool.

Although all over the world we experience different climates in general high temperatures and humidity is giving all sows, especially during lactation a challenge. This impact of higher temperature and humidity on sow performance is better known as heat stress. Heat stress in lactating sows has been shown to lead to a reduction in feed intake, milk production, reproductive performance and indirectly the growth rate of piglets. These adverse effects can already occur when ambient temperatures rise above 23-25˚C.


So, what is happening and how can we support the sow to minimize loss of performance? High temperatures and humidity, what is happening?


Heat stress in pigs occurs when ambient temperatures rise above the thermoneutral zone of the pig and the animal’s body cannot get rid of the excess body heat. Pigs, unlike some other animals, do not have functional sweat glands. In this way, they are not able to sweat and get rid of body heat efficiently. This means that when ambient temperatures rise a sows’ body temperature is also likely to rise.

For a lactating sow, the optimal ambient temperature lies below 20˚C. When temperatures rise above 23-25 degrees heat stress can already occur. Next to ambient temperature also relative humidity influences this (upper) temperature, showing that with higher humidity heat stress in lactating sows can already occur with lower ambient temperatures.

piglets and sow

When sows are exposed to heat stress, they adapt their behaviour to lose (more) body heat. One of these behaviours is that they start panting and that feed intake decreases. This is because feed intake and the digestion of feed will contribute to further heat production in the sows’ bodies. A meta-analysis performed by Ribeiro et al. (2018; based on 20 scientific articles) to evaluate the effect of heat on the performance of lactating sows and their litters showed that for each degree of increase in ambient temperature there was a mean feed intake reduction of 148 g/d (see figure). Research by Renaudeau et al. (2003) even showed that each increase of one degree in the ambient temperature between 25˚C and 27˚C with humidity ranging between 50% and 60%, caused a feed intake reduction of 214g/d.

Graphic effect of temperature on sow performance

Milk production is (mainly) affected by feed intake as a result that heat stress also highly negatively affects milk production. With each degree increase in ambient temperature a 227 g/d reduction in the sows’ milk production could be seen (Ribeiro et al., 2018). This has indirectly adverse consequences for the performance of the piglets.

What can you do to support your sows?

To minimize loss of performance and eventually profit, herewith are three important but sometimes overlooked tips.

 1. Feed sows smaller but more frequent meals during the day and feeds during the coolest parts of the day. Next to feed, also make sure that the sow has access to (extra) water. Especially before and after farrowing, to optimally initiate milk production and improve feed intake. Hygiene is also an important topic to pay attention to as higher temperatures increase the risk of spoiling the feed provided to the animals. Make sure to keep the feed fresh to increase feed intake.

To stimulate feed intake, fresh air could also be provided at the head of the sow. The fresh air results that the sow’s perceived temperature going down which makes her better able to evaporate water in the lungs and consume the feed.


2. Alter the nutritional balance of the diet. The performance of lactating sows exposed to high temperatures can be improved by reducing the animal’s heat production by, for instance, lowering the crude protein level or using less fibre. Also, replace starch with fat as an energy source. Fat is an excellent source of energy and an ingredient that generates less heat during digestion.

However, make sure to feed a palatable and good digestible fat source, like the type of fat used in Lactolat. Lactolat is a dairy-based ingredient specially designed for sows during lactation containing active ingredients to stimulate appetite and improve feed intake, and micro-encapsulated fat based on coconut and palm oil. 

nutrifeed lactolac

3. Support the piglets. The decrease in feed intake of the sow during lactation due to heat stress hurts milk production. Therefore, it is important to support the piglets during lactation by feeding them additional milk, like Porcolac.

Porcolac is a premium milk replacer, packed with the right nutrients from dairy supplemented with essential vitamins, minerals and our Imagro health concept.

In this way, sows get supported for fulling the needs of the piglets not at the expense of the milk yield of the sow and the piglets benefit from the extra nutrients and energy provided by the milk replacer.

Nutrifeed Porcolac

Want to know more about our products to support sows and piglets?

Contact our Animal Nutrition team via for more information and support.


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Piglet and Sow Performance Programme
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