The aim of adopting measures to combat heat stress is not only to keep poultry birds alive but also to get production out of them to achieve targeted figures i.e. number of egg from layers and a better body weight at particular age with specific FCR in broilers.
The following steps will help to combat heat stress in poultry birds:
- Housing Management
- Water Management
- Feed Management
- General Management
1. Housing Management for Poultry Birds
a) Orient the long axis of poultry house in an east-west direction to minimize solar heating and directed access to sunlight.
b) Poultry houses in tropics should have good roof insulation (if possible with false roof to reduce the conduction of heat) with support of foggers and cooler systems.
c) In open sided houses, width of house will be a limiting factor so keep the optimum width (24-32 ft) based on temperature, humidity and wind velocity, type of house and nature of bird for effective cross ventilation.
d) Increased air movement over the birds by cooler fans/exhaust to produce a wind chill effect which will cool birds even without drop in the house temperature.
e) Shed design and construction should not allow direct sunlight on birds.
f) Thatching of roof with paddy straw or sugar cane leaves will reduce temperature inside the shed.
g) The roof should be painted with white wash to reflect light.
h) Shades from tall trees and plantation around the sheds can reduce the radiant heat. The plantation of trees should be such that trees will be leafy during summer and bald during winter.
i) Roof overhangs should be sufficient (3-5 ft) to protect the birds from strong sunrays.
2. Water Management for Poultry Birds
Practically water is the most important criteria of these four managemental factors during summer. In summer water consumption is 3-4 times more. Even a slight shortfall of water can lead to heat stroke and mortality. Normally feed and water consumption ratio is 1:2 but when temperature shoots beyond 95ºF, this ratio may increase up to 1:4 or more.
Points to be taken into consideration include:
- Supply of plenty of clean and cool water (60-70ºF) must be ensured during summer months.
- Use good quality sanitizers in water to control infections through water.
- For day old chicks provide cool water and electrolytes on their arrival to farm before offering feed to avoid dehydration after transportation.
- Cover water tanks with wet gunny bags to avoid direct exposure to sun.
- Increase number of waterers by 25%.
- Increase frequency of watering.
- In case of nipple drinkers, insulate nipple pipe with wet gunny cloth.
- Provide electrolyte (1-2 gm/liter) in water during hot hours.
- Addition of 0.25% of salt to drinking water increases water consumption.
- Adjust the amounts of medications and volumes of water used for water vaccination to reflect the increase water consumption of the flock during hot weather.
- Do not withhold drinking water from the flock when vaccine is provided through drinking water.
3. Feed Management for Poultry Birds
- During summer consumption of feed by birds is reduced considerably leading to reduced body weight, egg production and shell quantity.
- Increase the frequency of feeding.
- Do not offer feed during day time in broilers.
- Certain changes in feed formulations are necessary.
- Increase nutrient density of feed to compensate for depressed feed intake.
- Energy of feed should be reduced. Crude protein content should not be increased because heat generated by one gram of fat is 16.5% or one gram of fat is 22.5%.
- Similarly, 20-30% extra vitamins and trace minerals should be added to feed.
- Available phosphorous content of feed should be increased.
- Vitamin C is necessary to maintain integrity of blood vessels. Supplementation of vitamin C at 200-500 gm/ton feed will be beneficial.
- vitamin E at 50 gm/ton feed will also be beneficial.
- Pelleted feeding is beneficial where low energy fiber diets are used.
- Add soda-bicarbonate at 0.1% for improvement of shell quality.
- Since hot humid climate favors growth of moulds/fungi in feed, so constant use of anti-fungal is recommended.
- The diet should be balanced with limiting amino-acids, Methionine and lysine which will give better results.
- Increase the calcium level from 3-3.5% in layer diet.
- Inclusion of Vitamin A 8000 IU and Vitamin E 250mg/kg diet for better performance and combat heat stress.
4. General Management Practices for Poultry Birds
- Litter preferably fresh litter of 2 inches thickness with racking or stiring of litter 2-3 times a day during cool hours is recommended.
- 10% extra floor space should be provided in summer.
- Overcrowding of birds should be avoided.
- Shifting, transportation, de-beaking and vaccination should be done during night or cool hours of the day.
- Birds severely heat stressed may be dipped in cold water for 2-3minutes keeping their neck and head above the water level.
- Provide proper cross ventilation.
- Fans (pedestal, ceiling or exhaust) may be fitted in sheds.
- Use foggers in the shed which could reduce the shed temperature up to 5-10ºC depending upon quality.
- Use of paint, white lime etc practically reduces the shed temperature up to 2ºC
- Use side curtain in shed which should be sprinkled with water.
- Provide 3 exhaust fans on one side and pad cooling on other side (200ft) which completely seals the shed sides and brings down temperature below 8ºC.
- Use sprinklers on the top or inside shed.
- Surround the house with tall trees.
- Thatched roof is suitable for hot areas.
- The house should be situated away from other buildings in order to facilitate free movement of air.
- High altitude of roof is ordinarily 2.6 to 3.5m from foundation to the roof line to provide maximum ventilation.
- Provide 1meter overhang to cut the direct sun and rain into the house.