Early-age cold conditioning of broilers: effects of timing and temperature

Area of Science:

• Animal Science
• Poultry Science
• Avian Physiology

Background:

• Broiler chickens often suffer from ascites mortality, impacting performance.
• Early-age environmental stressors can influence broiler development and health.
• Understanding the physiological adaptations to cold is crucial for optimizing broiler production.

Purpose of the Study:

• To investigate the impact of early-age cold conditioning (CC) on broiler performance.
• To assess the effects of CC on ascites mortality, thyroid hormone status, and immune response.
• To determine the optimal conditions for CC in broiler chickens.

Main Methods:

• A 2x2x2 factorial experiment exposed 336 broiler chicks to different cold temperatures (20°C or 25°C) and durations (3h or 6h) at 2-3 days of age.
• Control groups were maintained under standard conditions (30°C).
• Birds were reared to 42 days, with performance, carcass traits, heart weight, ascites mortality, leucocyte count, and thyroid hormone levels (T3, T4) measured.

Main Results:

• Cold conditioning significantly improved weight gain and feed efficiency.
• Ascites mortality and heart weight were reduced in cold-conditioned birds.
• Total leucocyte count increased, plasma thyroxine (T4) concentrations rose, and the triiodothyronine (T3) to T4 ratio decreased in CC groups.
• Optimal CC was observed at 20°C for 6 hours at 2 days of age, with no benefit from repeated CC.

Conclusions:

• Early-age cold conditioning enhances broiler performance and reduces ascites mortality.
• The benefits are linked to improved thyroid hormone metabolism and leucocyte function.
• Specific cold exposure parameters (20°C for 6h at 2 days old) are most effective for broiler CC.