Polled cattle

Polled livestock are without horns in species which are normally horned. The term refers both to breeds or strains that are naturally polled through selective breeding and also to naturally horned animals that have been . Natural polling occurs in cattle, yaks, water buffalo, and goats, and in these animals it affects both sexes equally; in sheep, by contrast, both sexes may be horned, both polled, or only the females polled. The history of breeding polled livestock starts about 6000 years BCE.

The archaic term or is sometimes used to refer to hornless livestock (especially cattle) in folk songs, folk tales, and poetry, and in the name of the polled Irish Moiled cattle breed. "Muley" derives from Irish and Scottish Gaelic maol, and Welsh moel.

In cattle, the polled allele is genetically dominant to that for horns. The polled trait is far more common in beef breeds than in dairy breeds. CRISPR technology is being developed to create polled versions of dairy breeds.

In sheep, the allele for horns in both sexes is partially dominant to the allele for being polled in both sexes, and both of these are dominant to that for polling in the female only.

The development of wholly polled strains in goats has been discouraged by a 1944 study that suggested a link between the polling gene and hermaphrodism. Unfortunately, little study on the subject has occurred since. Naturally polled water buffalo also have genital defects.

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