Pre-cold acclimation improves the immune function of trachea and resistance to cold stress in broilers

Area of Science:

• Animal Science
• Immunology
• Environmental Physiology

Background:

• Environmental factors significantly impact poultry health and immunity.
• Cold stress can compromise the integrity and function of the avian respiratory system, particularly the trachea.
• Acclimation strategies may mitigate adverse effects of cold exposure on broiler immunity.

Purpose of the Study:

• To investigate the effects of varying cold stimulation levels on broiler tracheal immunity.
• To assess the impact of cold acclimation on resistance to acute cold stress.
• To analyze gene and protein expression related to immunity and stress response in broiler tracheas.

Main Methods:

• 360 broiler chicks were divided into control and two cold-stimulated groups (3°C and 12°C reduction).
• Birds were subjected to chronic cold stimulation from day 8 to 42, followed by acute cold stress.
• Tracheal tissues were analyzed for gene expression (immunoglobulins, antimicrobial peptides, Hsps, cytokines) and protein levels, alongside morphological changes.

Main Results:

• Mild cold stimulation (3°C lower) resulted in intact tracheal structure and increased immunoglobulin and antimicrobial peptide gene levels.
• Severe cold stimulation (12°C lower) led to tracheal destruction, decreased immunoglobulins, and elevated Hsps and proinflammatory cytokines.
• Acclimated broilers (mild cold) showed enhanced tracheal immunity and better resistance to acute cold stress compared to non-acclimated or severely stimulated groups.

Conclusions:

• Cold acclimation at 3°C below ambient temperature from day 8 to 42 enhances broiler tracheal mucosal immunity.
• This acclimation improves resistance to subsequent acute cold stress.
• Severe cold stimulation negatively impacts tracheal integrity and immune function in broilers.