Young horses require specific levels of amino acids, vitamins, and minerals for proper development, and researchers know that zinc, in particular, is vital for growing horses’ enzyme and immune function. However, there’s been little research done in horses evaluating the relationship between zinc and the equine immune system. So researchers from Argentina’s Buenos Aires University set out to evaluate zinc levels and serum protein profiles in foals of different ages.

Veterinarians know that zinc deficiencies can result in decreased cell-mediated and humoral (an antibody response to an antigen by the immune system) immune responses, by causing a reduction in monocyte (a type of white blood cell that converts into infection-fighting macrophages), cytokine (inflammation mediators), and leukocyte (another type of white blood cell that fights infection and is involved in inflammation) function.

To learn more, Emilio Adrián De Simone, DVM, PhD, and colleagues employed 304 race-type horses—70 weanlings aged 8-10 months, 125 yearlings aged 12-18 months, and 109 2-year-olds aged 20-24 months—at different farms in Buenos Aires and La Pampa, Argentina. All foals grazed pasture ad libitum and consumed appropriate amounts of a commercial feed containing 40 ppm (parts per million) zinc sulphate, as recommended by the National Research Council in 2007, to meet their individual nutritional needs.

Researchers collected blood samples from all the foals and analyzed zinc, protein, and albumin concentrations in the serum. Then, based on serum zinc concentration, the team classified the foals as either low zinc (less than 100µg/dL ) or normal zinc levels (100-160µg/dL). The team also randomly selected 78 samples—41 from the low zinc group and 37 from the normal group—and analyzed them for γ-globulin concentration; γ-globulin is an indicator of immunoglobulins, or antibodies, in the blood