Heat Stress in Poultry
By Dr Rob Marshall
Losses from heat stress in backyard and exhibition poultry will become a greater problem now and into the future as summer temperatures increase as a result of climate change.
Chickens may acclimatize to hot temperatures (30 - 33 degrees Celsius) over a period of 5 days but become vulnerable to very high temperatures because they are unable to adjust to very hot weather (33-45 degrees Celsius) that appears suddenly. A heat stress prevention strategy is therefore needed before, during and after these very hot days if losses are to be avoided. A preventative approach is necessary because emergency first aid treatment is rarely successful when advanced signs of heat stress are already present. Treatment may, however, be successful when initiated during the early stages of heat stress.
Prevention Strategy for Heat Stress
When temperatures are forecast above 33 degrees Celsius the following suggestions should help control the effects of heat stress (and reduce losses if temperatures then unexpectedly rise above 40 degrees Celsius).
Add 5ml Quickgel and 20ml of Apple Cider Vinegar into 2 litres of cool drinking water. Apple cider vinegar is high in potassium, which is lost from the body in heat stress. Potassium in drinking water makes birds drink more. When temperatures are forecast to be above 40 degrees Celsius add 5 teaspoons of Sodium bicarbonate (Bicarb Soda - baking soda) into the same 2 litres of drinking water. Bicarb soda helps to control heat stress acidosis.)
Feed early morning then remove the food so that the chickens do not eat for 6 hours before the hottest part of the day as the eating process increases body temperature.
Reduce the number of birds in a pen to prevent overcrowding and provide fans to improve ventilation.
Mist spray the birds. Do not wet the roof of the coop.
Continue above treatment each day of the hot spell. When cooler weather returns provide Quikgel (2 mls/litres of drinking water) for two days to stimulate the appetite of stressed birds.
Immediate Treatment of Heat Stress
Treatment for heat stress is most successful when the afflicted birds are treated in the early stages of heat stress. The body temperature of a healthy chicken is 41- 42 degrees Celsius. When this temperature rises by 4 degrees Celsius to 46 degrees Celsius chickens will die irrespective of every effort to save them. It is best to initiate heat stress treatment at the first indication that the chickens' body temperature has risen above its thermo-neutral zone (the temperature range in which chickens are able to behave normally). This treatment, which is given when the first signs of heat stress appear, will save birds by preventing the condition of heat stress deteriorating too far.
When the body temperature of chickens rises above the thermo-neutral zone, they will try to cool themselves down by changing their normal behaviour. The earliest signs of heat stress may be detected by monitoring for the following changes in the chickens' behaviour. Chickens will try to cool down by first trying to move away from each other and towards cooler places or against cool surfaces (walls etc.). As the birds become hotter they will show more obvious signs of heat stress - slow panting (poultry may sustain slow panting as a cooling mechanism for long periods so there is usually an opportunity to help halt the heat stress process at this stage), holding wings out from body, increased thirst, decreased food intake and inactivity.
At this early stage of heat stress:
Add 5ml Quickgel, 20ml of Apple Cider Vinegar and 5 teaspoons of Sodium bicarbonate (Bicarb Soda - baking soda) into 2 litres of cool drinking water.
Separate birds into small groups. Do not pick them up but make them walk which helps them reduce their body temperature.
Remove access to grit for 3 days
Mist spray birds. Do not the roof of the coop.
Provide fans to improve ventilation, which also helps them to reduce their body temperature.
Emergency First Aid Treatment
This treatment may be given to birds found in an advanced stage of heat stress, although the outlook for recovery is poor. The signs of advanced stage of heat stress include fast panting, darkening of the skin and combs, obvious physical tiredness, inability to stand.
Dunk bird in a cold-water bath for 2 minutes. Crop feed with 30mls of a cool solution of Quikgel and Sodium bicarbonate (2% solution) each 4 hours until the birds are standing then 3x daily until they resume eating again. Place bird on straw in air- conditioned room with another chicken or in view or hearing range of the chicken flock. Provide cool drinking water with Quikgel, Apple cider vinegar and Bicarb soda (see above dosages) until eating.
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