The effect of dietary selenium on humoral immunocompetence of ponies.

This research study investigates how supplying selenium, a dietary supplement, affects the immune response in ponies, revealing that ponies with a selenium-enriched diet showed improved immune function.

Research Methodology

• The researchers used fifteen Shetland ponies for a trial run over seven weeks, aiming to determine selenium’s impact on the production of humoral antibodies, a vital aspect of the immune response.
• Four 3-year-old, five 2-year-old, and six yearling ponies had their selenium levels depleted before starting the trial.
• The ponies were divided into two groups and fed either a diet low in selenium (.02 ppm), or a diet higher in selenium (.22 ppm).
• Upon receiving their respective diets, each pony was presented with an antigenic challenge, specifically receiving 2 ml of packed red blood cells from sheep. This challenge was repeated 2 weeks after the initial administration.
• Throughout the experiment, blood samples were collected weekly and tested for glutathione peroxidase activity (an enzyme indicating oxidative stress), selenium levels, concentration of immunoglobulins (antibodies), and antibody titers (concentration).

Research Findings

• Results showed significant differences between the two groups. Ponies on the selenium-supplemented diet displayed higher glutathione peroxidase activities and blood selenium concentrations, particularly notable in the later weeks of the trial.
• This group of ponies also exhibited an enhanced primary immune response, indicated by increased hemagglutination titers, which reflects the ability of the pony’s antibodies to agglutinate (or clump together) foreign cells.
• Furthermore, the selenium-enriched diet led to higher IgG concentrations. IgG is a type of antibody, and higher levels suggest a more robust immune response.
• The findings imply that a dietary selenium concentration of .02 ppm may not suffice for optimal immune function in horses, indicating that selenium supplementation could help in boosting immunocompetence making them resistant to infections and diseases.