Stress is a state in which homeostasis is threatened. It is the organism’s reaction or biological response to stimuli that disrupt its normal physiological equilibrium or homeostasis. Heat stress is a common problem for poultry producers, whether seasonally or year-round. In general, broiler breeds are more suceptible than layers and rapidly growing broilers are more prone to heat stress.

Common causes of heat stress are:

  • High environmental temperature
  • Overcrowding
  • Inadequate ventilation
  • Insufficient water supply
  • High humidity

Symptoms – Elevated wings, open mouth breathing or panting, increased water intake, reduced feed consumption, decline in egg production and size of eggs, thinning of shell, reduced growth rate and poor meat quality in broilers. Diarrhoea, convulsions and seizures are also observed.

Strategies to manage heat stress

  • Houses should be of adequate height and width to ensure proper ventilation and stocking density should be reduced.
  • Sheds should be insulated for limiting solar heat gain. Besides this, use of fans, evaporative coolers and water sprinklers in farm preferably without the birds themself getting wet
  • Plenty of clean and cool drinking water should be provided to birds ad libitum.
  • Addition of feed additives like betaine, enzymes, antioxidants, mycotoxin binders, phytogenics, and probiotics in poultry feed alleviate the effects of heat stress and also improves food digestibility.
  • Offering feed as pellets along with controlled fasting and dual feeding program (protein diet during the cooler phase and an energy-rich diet during the warmer phase of each day) reduces body temperature and improves performance.
  • Addition of electrolytes (NaHCO3, NH4Cl etc.) and vitamins particularly Vitamin C to drinking water increases water consumption and increase tolerance to heat stress.
  • Selection of breeds with increased resistance to heat stress and early life conditioning (i.e., perinatal heat acclimation).

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