Hatching phase influences thermal preference of broilers throughout rearing

Area of Science:

• Animal Science
• Poultry Science
• Thermoregulation

Background:

• Understanding broiler thermoregulation is crucial for optimizing growth and welfare.
• Incubation conditions can influence post-hatch physiological responses.
• Hatching patterns, defined by the timing of internal and external pipping, are a novel area of investigation.

Purpose of the Study:

• To investigate the effects of hatching patterns (Short-Long vs. Long-Short) combined with high incubation temperature on broiler thermal preference and heat stress response.
• To determine how these factors influence growth performance metrics such as feed intake, feed conversion, weight gain, and body weight.

Main Methods:

• A 2x2 factorial design was employed using broiler breeders (Cobb-500®).
• Treatments included two hatching patterns (Short-Long, Long-Short) and two incubation temperatures (control 37.5°C, high 39°C from day 13).
• Chicks were reared in climate chambers, and thermal preference, respiratory frequency, and growth parameters were assessed throughout the rearing period.

Main Results:

• Broilers with Long-Short hatching patterns and control incubation temperatures preferred lower ambient temperatures.
• Broilers with Short-Long hatching patterns and high incubation temperatures preferred higher temperatures from 21 days of age.
• High incubation temperature increased respiratory frequency, indicating heat stress. Short-Long hatching improved feed conversion, weight gain, and body weight, while high incubation temperature negatively impacted these metrics.

Conclusions:

• Hatching patterns, particularly when associated with incubation temperature, significantly influence broiler thermal preference and heat response.
• The Short-Long hatching pattern improved growth performance, whereas high incubation temperature impaired it.
• Separate rearing of chicks with different hatching patterns may be beneficial, though challenging in practice.