Nutritional strategies to fight heat stress in poultry

Nutritional strategies to fight heat stress in poultry

Vitamins, electrolytes and essential oils help to keep your farm profitable during Summer time

High temperatures have a major impact on poultry farming. When they are coupled with high humidity, the combination is critical for the health and productivity of the animals.

Poultry are homeotherm animals, which means that they are able to maintain a constant body temperature by regulating metabolic heat production and heat loss. In the ‘thermoneutral zone’ (20-24ºC) birds are able to control their heat loss: body temperature is held constant, feed intake is maximized and FCR is optimum. But as temperatures increase, birds are not able to control their body temperature and it starts rising above 41ºC.

Fully feathered broilers (about five weeks of age), layers and breeders are the most sensitive to heat stress. Males are the most susceptible because they produce more endogenous heat.

Heat Stress Index (HSI) is the sum of environmental temperature (when it is above 27ºC) and relative humidity. This index is useful to determine the onset of heat stress, that starts when the index is higher than 105.

Affected birds show signs such as:

  • Fast panting (from normal breathing of 25 breaths/minute to 250 breaths/minute). Panting causes respiratory alkalosis as blood carbon dioxide levels diminish due to hyperventilation. Respiratory alkalosis leads to an excess of bicarbonate in blood, which is eliminated through urine, eliminating also other important ions such as Na+, Ca2+, Mg2+, K+ and water.
  • Birds lift their wings away from their bodies.
  • Loss of appetite: At an environmental temperature of 28ºC, feed intake is depressed by 12%. For every degree above 32ºC, the bird further reduces its feed intake by 5%.
  • Increase in water intake: bird increases its water intake by 4% for every 0.5ºC above 21ºC.
  • Metabolic (serious acid-base balance disorders, ascites), digestive (wet droppings), skeletal (bone problems due to metabolic imbalance) and respiratory disorders. In many trials and farm experiences, phyto-active ingredients have proved to be useful in digestive problems due to hot weather, as you can find in this link.
  • Rise in cannibalism.
  • Raise of mortality.
  • Lethargy.
  • Drop in productivity: In broilers, FCR worsens by 10-12% and growth slows down by 5-10%. In layers and breeders, laying rate declines, eggshell quality worsens, replacement pullets are lighter, lay later and lay fewer eggs. In breeders, fertility is reduced, due to less mating, poorer semen quality and female infertility.

Nutritional strategies to fight heat stress in poultry

Nutritional strategies to cope with heat stress

  • Supplementing feed with energy (by increasing the percentage of vegetable oils or fats) helps to avoid productivity losses. This practice is useful in hens and in broilers, but, in the case of broilers, the resulting meat could be fattier, so it is necessary to be cautious.
  • Levels of lysine and methionine should be increased.
  • In breeders and layers, administration of calcium should be increased by 4-5%. Moreover, partially replacing salt by sodium bicarbonate helps to maintain eggshell quality.

Treatments through drinking water are more effective than through feed because during hot periods birds eat less but do not reduce their water intake. The following additives are key during hot periods:

  • Electrolytes: Electrolytes supplementation need to be increased due to acid-base imbalance derived from heat stress. Birds loose more electrolytes through feces and this loss needs to be compensated in order to maintain health and productivity.
  • Vitamin C: supplementation with vitamin C can reduce the negative consequences related to a rise in plasmatic corticosterone. Corticosterone is the main hormone related to stress in poultry.  Heat stress can cause up to fivefold increase in plasma concentrations of corticosteroids. Supplementing with vitamin C limits the increase of body temperature, stimulates growth in broilers, improves the quality of the carcass and it is related with increased laying rate, stronger eggshell and healthier day-one-chicks.
  • Vitamin E: all studies show an immunosuppressing effect of heat stress on broilers and hens. Supplementing with vitamin E has shown to make the birds more resistant to disease and increase feed intake during heat stress.
  • Refreshing essential oils: essential oils with a fresh taste, such as eucalyptus, provide a cool sensation caused by the stimulation of oral mucosa sensory cold receptors, giving the birds a very pleasant sensation of ‘freshness’. Thanks to this refreshing sensation, feed intake recovers, productivity increases and mortality drops. It has also been shown that behavior related to heat stress, such as wing lifting and panting, is ameliorated with the addition of refresing essential oils to drinking water.

Nutritional strategies to fight heat stress in poultry

Useful management tips

  • Avoid any circumstance that causes excessive bird density.
  • Outside the house, spraying the roofs of with water. Roofs can also be covered with insulating materials such as hay, canes, straw, etc.
  • Use curtains to protect the birds from direct hot winds.
  • Use internal nebulizers to spray mists of cool water. Fresh essential oils can be added to the water for a better refreshing effect.
  • Provide cool drinking water. Flush the water system often to water does not get too hot.

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. Contact with us for more information on the use of the product.

PhytoMax© is a combination of chelated minerals, vitamins and essential oils to be added through drinking water, designed to improve productivity of laying and breeding hens.

PlusProtect Digestive© is a liquid cocktail of highly active phyto-active ingredients, designed to easily administer beneficial compounds through drinking water.

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

Copyright © 2015 PlusVet Animal Health, registered trademark.
Safe Creative #2007170344352

Pictures: Chicken, Shutterstock. Water splash, Green leaf, Unsplash.

Certain health statements may not be applicable in your geographical region. Product claims may differ based upon the requirements of your government.

Posted in: GrowthPlus Poultry, PlusBreathe, PlusLay Immuno, PlusProtect Digestive Poultry, Poultry

Leave a Comment (0) ↓