From feather pecking to immunity: Immune differences between lines selected for high and low feather pecking

Area of Science:

• Animal behavior
• Immunology
• Genetics

Background:

• Feather pecking (FP) is a significant welfare issue in laying hens, causing feather damage and cannibalism.
• The underlying mechanisms of FP are not fully understood, but a link to the immune system is increasingly discussed.
• Human studies show connections between personality traits like impulsivity and immune system alterations.

Purpose of the Study:

• To investigate immunological differences between laying hens selectively bred for high (HFP) and low (LFP) feather pecking behavior.
• To explore the hypothesis that feather pecking may be an immune-related behavioral response.

Main Methods:

• Analysis of leukocyte subsets in blood, spleen, and cecal tonsils.
• Assessment of mitogen-induced lymphocyte proliferation response.
• Measurement of antibody concentrations in HFP and LFP hens.

Main Results:

• Divergent selection successfully altered FP behavior, with HFP hens exhibiting significantly more pecking.
• HFP hens had reduced numbers of T helper cells, CD4+ CD25high cells, and B cells.
• HFP hens showed enhanced T cell proliferation to ConA but reduced T cell-dependent B cell proliferation to PWM.

Conclusions:

• Significant immunological differences exist between HFP and LFP hens, particularly in T cell immunity.
• These findings support the hypothesis that feather pecking behavior is associated with immune system alterations.