The bony structure on a cow’s forehead from which its horns grow is the horn core.
A cow’s horn consists of a permanent bony core covered by a keratin sheath. The horn core is connected to the skull and contains extensions of the frontal bone. Unlike deer antlers, cattle horns are not normally shed and regrown every year.
The outer sheath is made of keratin, the same structural protein found in hair, fingernails, and feathers. As cattle grow, the horn sheath develops annual growth rings that can sometimes help indicate age, although nutrition and other conditions affect their appearance.
Cattle breeds differ in horn size, shape, and presence. Some naturally polled breeds have been bred without horns, while other cattle may be dehorned or disbudded in managed settings. “Antler” is the wrong term for cattle because antlers are branched structures that are typically shed by members of the deer family.