The invention provides a preparation method of a feed-grade
zinc oxide premixing agent. The preparation method comprises the following steps of (1)
grinding zinc oxide powder, performing screening with an 80-mesh
sieve to obtain
fine powder, adding the
fine powder into an
ethanol water solution, dropwise adding a
silane coupling agent solution, and taking suspension liquid for standby application; (2) adding a
delta-
tocopherol-
ethanol solution to the suspension liquid under the normal
atmospheric temperature, performing heating to 60-70 DEG C, performing a reaction for 2-3 hours, taking suspension liquid, performing filtering, washing filter cakes with
ethanol, performing
drying, performing
grinding, and performing screening so as to obtain nanometer
zinc oxide; (3) mixing the nanometer zinc oxide with
starch,
sodium hydroxypropycellulose,
sodium cyclamate, a binder and a
wetting agent through a mixing
machine, performing
granulation, performing shot blasting, and performing
drying to obtain mini pills; and (4) performing screening on the mini pills with a classifying
sieve so as to obtain the feed-grade zinc oxide premixing agent of which the particle size is 20-80 meshes. The zinc oxide particles in the made zinc oxide premixing agent are dispersed in a nanometer grade, so that the feed-grade zinc oxide premixing agent is uniform to disperse and not liable to
agglomerate, has favorable
biological value and utilization, and cannot generate side effects on growth of animals.