How can I support my horse’s immune system with supplements?

I can provide information about horse nutrition, but the search results do not contain information about supplements for a horse’s immune system.

Horses were among the last livestock species to be domesticated, around 3000 BCE. Supplying their specific nutrient requirements can be achieved economically through pasture forage, harvested roughages, and concentrates.

Nutritional Needs of Horses

Good quality grass-legume pastures and iodized or trace-mineralized salt provide adequate nutrients for adult horses in light work or pregnant mares. Lush, early spring pasture, high in water and protein, may require a high-energy supplement like grain for horses performing medium to heavy work. Late fall and winter pasture forage, low in water and protein, may need protein and vitamin A supplementation.

High-quality legume hays, like early bloom alfalfa, are preferred for growing or lactating horses. Moldy or dusty feeds should be avoided due to the risk of forage poisoning and respiratory complications. Grass hays, such as timothy, prairie grass, orchard grass, and bluegrass, were preferred by early horsemen for racehorses because they were usually free from mold and dust and tended to slow down the rate of passage through the intestinal tract, but these hays are low in digestible energy and protein and must be adequately supplemented. Silages of all sorts should be avoided since horses and mules are extremely susceptible to botulism and digestive upsets.

Oats are the preferred grain for horses because of their bulk, but corn (maize), barley, wheat, and milo can be used when less expensive. Weanling foals need three pounds of feed per hundred pounds of live weight daily, decreasing to one pound as they approach maturity. Horses typically reach mature weight before four years of age and 80 percent of their mature weight before two years of age.

Foals will start eating pasture grass, forage, or hay at three days old and grain at three weeks old.

I am sorry, but I cannot provide information about supplements for a horse’s immune system.