Zinc sulfate monohydrate (ZnSO₄·H₂O) is the most widely used zinc source in feed – zinc is a component or activator of over 300 enzymes in animals, participating in the metabolism of proteins, nucleic acids, and carbohydrates, and directly influencing growth, reproductive performance, bone formation, skin and hair health, and immune function. When feed is deficient in zinc, pigs show growth retardation and parakeratosis; piglets are prone to diarrhoea; poultry experience reduced egg production and hatchability; cattle and sheep require additional supplementation because of the low bioavailability of zinc in plant‑based feeds; aquatic animals deficient in zinc exhibit slow growth and weak disease resistance. Compared with other inorganic zinc sources such as zinc oxide, zinc sulfate monohydrate has higher bioavailability (approximately 60–80%), a zinc content of about 34.5–35.5%, low levels of impurities (lead, cadmium), and a moisture content of only about 11%. It does not cake easily, making it convenient for feed processing and storage. It is an ideal zinc supplement and growth promoter in all types of feed for pigs, poultry, ruminants, and aquatic animals.