Feed-Grade Zinc Sulfate

Feed-Grade Zinc Sulfate

Zinc sulfate is commonly available in two forms: zinc sulfate monohydrate and zinc sulfate heptahydrate.
Zinc sulfate monohydrate appears as a white or off-white powder. It is easily soluble in acidic solutions, slightly soluble in water, and insoluble in ethanol. The feed-grade product has a main content ≥94.7% and a zinc content ≥34.5%.
Zinc sulfate heptahydrate appears as white transparent prismatic or needle-like crystals or crystalline powder. It is efflorescent, highly soluble in water, and insoluble in ethanol. Its main content is ≥97.3%, with a zinc content ≥22%.

In broiler diets, the maximum allowable addition of zinc sulfate (calculated as elemental zinc) is 150 mg/kg. Dietary zinc sulfate can meet 60–80% of a broiler’s zinc requirements and also supplies about 20% of its sulfur needs.

After ingestion, both forms of zinc sulfate must be dissociated into zinc ions and sulfate ions by gastric acid and intestinal digestive fluids before absorption. Zinc ions are absorbed throughout the small intestine, with the duodenum and jejunum as the main absorption sites, and the ileum playing a secondary role. In the duodenum and jejunum, zinc ions are actively transported by ZIP family transporters into intestinal epithelial cells. In the ileum, where the intestinal wall is thinner, zinc ions are absorbed more efficiently via passive diffusion through intercellular spaces and transmembrane channels.

Once inside the epithelial cells, some zinc ions bind to metallothionein for temporary storage, while others are transported out of the cells via ZnT family transporters on the basolateral membrane, entering the portal vein blood. In the bloodstream, zinc ions bind to albumin and are transported to the liver and throughout the body, participating in various physiological and metabolic activities.

Physiologically, zinc is involved in nucleic acid synthesis and protein metabolism, regulates hormone secretion, scavenges free radicals (working synergistically with vitamin E to reduce oxidative stress), promotes bone mineralization and skeletal cell proliferation and development, supports normal feather growth, and maintains the integrity and health of skin and tissues in livestock.