Immune Indicators of Welfare

The immune system is highly sensitive to stress and environmental challenges. Welfare problems often manifest as altered immune responses.

a. Stress and Immunosuppression

• Chronic stress elevates cortisol levels, which suppress immune activity.
• Leads to higher susceptibility to infectious diseases.

b. White Blood Cell (WBC) Counts

• Stress alters the ratio of neutrophils to lymphocytes.
• High neutrophil-to-lymphocyte ratio → indicator of chronic stress.

c. Immunoglobulin Levels

• Reduced antibody production (IgG, IgM, IgA) indicates weakened immune defense.
• Example: Low colostral IgG transfer in calves due to poor maternal care reduces immunity.

d. Disease Incidence and Morbidity

• Frequent disease outbreaks signal compromised welfare.
• Example: High prevalence of respiratory infections in overcrowded poultry houses.

e. Vaccination Response

• Poor welfare animals show weak serological response after vaccination.
• Indicates reduced immune competence.

f. Acute Phase Proteins (APPs)

• Proteins like haptoglobin, ceruloplasmin, serum amyloid A increase during inflammation or stress.
• Used as biomarkers of welfare status.