In vivo responsiveness of the broilers' adrenocortical system

Area of Science:

• Animal Physiology
• Endocrinology
• Chronobiology

Background:

• Broiler cockerels exhibit daily rhythms in corticosterone.
• Heat stress and adrenal manipulations can alter these rhythms.

Purpose of the Study:

• To investigate the interaction between circadian rhythms and broiler responses to heat stress and adrenal agents.
• To examine the effects of adrenocorticotropic hormone (ACTH) and dexamethasone acetate (DA) on corticosterone levels.

Main Methods:

• Measurements of serum corticosterone concentrations in broiler cockerels.
• Exposure to heat stress (HS).
• Injections of ACTH and dexamethasone acetate (DA) at different times of the day.

Main Results:

• Adrenocortical response (corticosterone) was higher early in the day for HS or ACTH-treated birds.
• Dexamethasone acetate (DA) showed greater inhibition of corticosterone when given later in the day.

Conclusions:

• Circadian timing influences broiler cockerels' adrenocortical responsiveness to heat stress and hormonal challenges.
• Strategic timing of interventions may modulate stress responses in poultry.