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Area of Science:

  • Animal Science
  • Avian Physiology
  • Animal Behavior

Background:

  • Photoperiod management is crucial for poultry production.
  • Understanding the impact of light exposure on broiler behavior and physiology is essential for welfare.
  • Melatonin rhythm synchrony is a key indicator of healthy circadian function in birds.

Purpose of the Study:

  • To investigate the effects of varying durations of light (14, 17, 20, and 23 hours) on broiler chicken behavioral patterns.
  • To assess the synchrony of 24-hour melatonin rhythms in broilers under different photoperiods.
  • To determine the relationship between photoperiod, behavior, and melatonin production in broiler chickens.

Main Methods:

  • Ross × Ross 308 male broilers were subjected to four lighting treatments (14, 17, 20, 23 hours of light).
  • Behavioral patterns (resting, standing, walking, feeding) were digitally recorded and quantified using scan sampling.
  • Melatonin levels were measured using radioimmunoassay at multiple time points over a 24-hour period.

Main Results:

  • Broilers exposed to 14 and 17 hours of light showed frequent linear and quadratic relationships between time and behavior during the photophase.
  • A quadratic relationship between time and melatonin was observed in flocks exposed to 14, 17, and 20 hours of light.
  • Broiler flocks exposed to 23 hours of light did not develop synchronized melatonin rhythms.

Conclusions:

  • Continuous light exposure (23L) in broiler chickens prevents the synchronization of melatonin rhythms.
  • Disrupted circadian rhythms due to excessive light exposure may lead to sleep fragmentation and compromised welfare in broilers.
  • Photoperiod management significantly influences broiler behavior and physiological rhythms, highlighting the need for optimized lighting strategies.