Early-age heat exposure improved growth performance and heat tolerance in broilers

Area of Science:

• Animal Science
• Poultry Science
• Environmental Physiology

Background:

• High temperatures pose significant challenges to broiler production, impacting growth, physiology, and survival.
• Understanding the long-term effects of early-life environmental conditions is crucial for optimizing poultry welfare and productivity.

Purpose of the Study:

• To investigate the impact of early-age high-temperature exposure on broiler growth, heat tolerance, and muscle development.
• To determine the molecular mechanisms, specifically gene expression related to myogenesis, underlying improved heat tolerance.

Main Methods:

• 440 Arbor Acres broilers were divided into control and early-age high-temperature exposure (EHT) groups.
• EHT group experienced 36 ± 1°C for 24h on day 3; both groups faced acute heat (35 ± 1°C for 5h) on day 43.
• Evaluated average daily gain, plasma glucose, gene expression (MyoD, Myf5), rectal temperature, and mortality.

Main Results:

• EHT broilers showed decreased average daily gain initially but increased gain from day 36-42.
• Plasma glucose levels were lower in EHT broilers.
• Significant upregulation of MyoD and Myf5 gene expression in skeletal muscle was observed in EHT group.
• EHT broilers exhibited enhanced heat tolerance, lower rectal temperature, and reduced mortality during acute heat exposure.

Conclusions:

• Early-age heat exposure improves broiler heat tolerance and reduces mortality during subsequent acute heat stress.
• This improved tolerance is linked to enhanced myogenesis through increased MyoD and Myf5 gene expression.
• Early heat conditioning can positively influence broiler performance and resilience.