Consequences of heat stress in boars, gilts and sows

Consequences of heat stress in boars, gilts and sowsEssential oils with fresh flavor relieve heat stress in boars, sows and gilts

Pigs are more sensitive to high temperatures than other species: they do not sweat, their lungs are small and they are covered by a thick layer of subcutaneous fat. Heat stress affects not only pigs in grower-finisher stage, but also the breeding herd.

Indeed, during the hottest period of the year, many pig farms experience a variety of reproductive problems in boars, gilts and sows. Such problems can be attributed mainly to two factors:

 1) Natural breeding cycle is seasonal

Wild pigs do not mate during the hot season, in order to avoid giving birth in winter, when the low temperatures impair the survival of the new born piglets.

Although selection through many generations of domesticated pigs has almost eliminated the seasonal breeding feature, some traces still remain, because physiologically the mating instinct is controlled by the photoperiod.

This problem can be reduced by adjusting the lighting hours during Summer and early Fall.

2) High temperatures inside the house

Environmental temperatures above 26ºC, especially together with high relative humidity, put the breeding herd at risk of heat stress. Temperatures above 30ºC are considered severe emergency levels.

There are three main obvious signs of heat stress in pigs:

  1. Increased respiration rate: when the pig is resting, the normal respiration rate is 15 to 25 breaths per minute. During early stages of heat stress, the rate increases to 40 breaths/minute, and in more severe cases, it raises to 60 breaths/minute or more.
  2. Lack of appetite: a lower feed intake allows the pig to cool down its internal temperature.
  3. Excessive water consumption: during heat stress, the pig may drink up to 6 folds the normal amount of water, which leads to an increased production of urine and a loss of electrolytes. This loss of electrolytes may result in diarrhea and, in severe cases, death. In addition, it has been proven that continue exposure to high temperatures disrupts the defense function of the digestive system, so digestive problems and infections are often associated to heat stress.

In the breeding herd, heat stress causes a variety of problems:

  • Boars show reduced libido.
  • Reduced fertility, due to poorer semen quality and female infertility
  • Reduced appetite in lactating sows, which will affect milk production, the growth and health of the suckling piglets, the time lapsus to the following oestrus and the fertility of the following cycle.
  • In extreme cases the pregnant sow may die, especially in the last weeks of pregnancy.

What can we do to reduce the heat stress in breeding pigs?

  • Adopt the necessary ventilation and cooling systems to maintain the temperature inside the house below 25ºC.
  • Use water to cool down the environment, through a sprinkling or a fogging system. PlusBreathe© can be added to water to boost the cooling down effect.
  • Schedule animal activities in the early morning or evening, when temperatures are cooler.
  • Reduce the movements of sows and boars as much as possible.
  • Let the boars be more in contact with the gilts and sows during oestrus.
  • Give cool drinking water to the animals.
  • PlusBreathe© can also be added to drinking water, to reinforce the refreshing effect.
  • Add a source of eletrolytes such as SupraPlus© to drinking water, to compensate the loss of electrolytes.

Consequences of heat stress in boars, gilts and sows

  • Increase the feeding frequency (4-5 times a day) and give fresh feed, to stimulate feed intake.
  • Increase the amount of fat in feed to make it more energetic and compensate the low feed intake.
  • Wean as early as possible to reduce the metabolic stress of the lactating sows.

Products of choice

PlusBreathe© is a liquid cocktail of refreshing essential oils to be given by drinking water and intended for all species and ages. It can also be sprayed in the air of the farm. Our experience in pigs show that spraying the product in the air of the farm or giving it by drinking water helps the animals to feel fresher and to overcome the problems associated with heat stress. Contact with us for more information on the use of the product.

SupraPlus© is a liquid mix that contains essential oils, electrolytes, rapidly absorbed sugars and vitamin E, and will be helpful to restore digestive balance during heat stress.

For more information on this topic and on our products, do not hesitate to contact us through

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