Assessment of lacrimal IgA as a potential parameter for measurement of long term stress in poultry.

This study, considering the stress of caging on laying hens, looks at the possible use of a product of the immune system; immunoglobulin A (IgA), as a representative measure of the effect of this chronic stress on the immune system of birds. Recording of serum corticosterone served as a traditional measure of stress. The study also considers the possibility of using IgA from the tears as a noninvasive source of samples. Lacrimal IgA is easily accessed by glycerol induction and measured by rocket immunoelectrophoresis. The amount of IgA in tears as well as in serum and possibly the synthesis of IgA seems to be affected by high levels of plasma corticosteroids. Lacrimal IgA levels vary independently of the IgA levels in plasma. It can be concluded that lacrimal IgA may be a useful marker of the effect of stress in poultry. Further studies are needed to facilitate a better understanding of the biological mechanisms that are involved, and to further examine IgA's usefulness as a long-term stress parameter.