Polled cattle breeds have been selectively bred to lack horns. Polledness is a dominant trait: all offspring of a bull with 2 copies of a polled-associated mutation will be polled themselves.
Phenotype: Naturally polled cattle have been selectively bred to lack horns.
Mode of Inheritance: Autosomal dominant
Alleles: H = Horned, Pf = Polled (Friesian molecular marker), Pc = Polled (Celtic molecular marker)
Breeds appropriate for testing: European cattle breeds (Holstein-Friesian, Jersey, Angus, Blonde d’Aquitaine, Dexter, Limousin, Charolais, Hereford, etc.)
Explanation of Results:
Cattle with H/H genotype will be horned and cannot transmit either of these polled variants to their offspring.
Cattle with Pf/H or Pc/H genotype will be polled and are heterozygous for the trait. They will transmit their polled variant to 50% of their offspring, and those calves will also be polled.
Cattle with Pf/Pf or Pc/Pc are homozygous and will be polled. Cattle with the Pc/Pf genotype are considered compound heterozygotes. Cattle with Pf/Pf, Pc/Pc, or Pc/Pf will transmit a polled variant to all of their offspring, and all calves they produce will be polled regardless of the mate's genotype.
From the time when livestock was first domesticated, modifications to the wild types have been selected both for animal husbandry and aesthetic reasons. Unique and large horns define cattle breeds such as Texas Longhorn, Highland Cattle, and Ankole Watusi. However, in modern times many cattle are maintained in more crowded conditions such as barns and small fenced pastures where polled phenotypes are more desirable for both beef and dairy breeds.
Recently, candidate mutations associated with polled phenotype in European breeds of cattle were found. There are 2 independent origins of polled, one found in Holstein-Friesian and Jersey breeds (Pf), the other in many European breeds of Celtic origin (Pc) such as Angus, Blonde d’Aquitaine, Dexter, Limousin, Charolais, and Hereford, among others. Polledness is dominant; a polled animal can have one or two copies of the polled alleles. All offspring of a homozygous polled bull (2 of the same polled allele, Pc/Pc or Pf/Pf) will be polled. Additionally, offspring with one copy of each of the polled alleles (Pc/Pf, compound heterozygous) will also be polled. Genetic testing is a cost-effective means to determine if a polled animal has 1 or 2 copies of the polled alleles.
Testing for the polled gene assists breeders in selecting cattle that have 2 copies of Polled gene.
HORNED. No copies of either Polled molecular marker are present.
POLLED. One copy of the Polled-Friesian molecular marker is present. At least 50% of the offspring will be polled.
POLLED. Two copies of the Polled-Friesian molecular marker are present. All offspring will be polled.
POLLED. One copy of the Polled-Celtic molecular marker is present. At least 50% of the offspring will be polled.
POLLED. Two copies of the Polled-Celtic molecular marker are present. All offspring will be polled.
POLLED. One copy of Polled-Celtic and 1 copy of Polled-Friesian molecular markers are present. All offspring will be polled.
Medugorac, I., Seichter, D., Graf, A., Russ, I., Blum, H., Göpel, K.H., Rothammer, S., Förster, M., & Krebs, S. (2012). Bovine Polledness – An autosomal dominant trait with allelic heterogeneity. PLoS One, 7(6), e39477. doi: 10.1371/journal.pone.0039477