Polled livestock are

livestock Livestock are the Domestication, domesticated animals that are raised in an Agriculture, agricultural setting to provide labour and produce diversified products for consumption such as meat, Egg as food, eggs, milk, fur, leather, and wool. The t ...

without horns in species which are normally horned. The term refers to both

breed A breed is a specific group of breedable domestic animals having homogeneous appearance (phenotype), homogeneous behavior, and/or other characteristics that distinguish it from other organisms of the same species. In literature, there exist seve ...

s and strains that are naturally polled through

selective breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...

and also to naturally horned animals that have been disbudded. Natural polling occurs in

cattle Cattle (''Bos taurus'') are large, domesticated, bovid ungulates widely kept as livestock. They are prominent modern members of the subfamily Bovinae and the most widespread species of the genus '' Bos''. Mature female cattle are calle ...

, yaks,

water buffalo The water buffalo (''Bubalus bubalis''), also called domestic water buffalo, Asian water buffalo and Asiatic water buffalo, is a large bovid originating in the Indian subcontinent and Southeast Asia. Today, it is also kept in Italy, the Balkans ...

, and

goats The goat or domestic goat (''Capra hircus'') is a species of goat-antelope that is mostly kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the famil ...

, and in these animals it affects both sexes equally; in

sheep Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ...

, by contrast, both sexes may be horned, both polled, or only the females polled. The history of breeding polled livestock starts about 6000 years BC.

Terminology

The archaic term or is sometimes used to refer to hornless livestock (especially cattle) in

folk songs Folk music is a music genre that includes traditional folk music and the contemporary genre that evolved from the former during the 20th-century folk revival. Some types of folk music may be called world music. Traditional folk music has be ...

, folk tales, and

poetry Poetry (from the Greek language, Greek word ''poiesis'', "making") is a form of literature, literary art that uses aesthetics, aesthetic and often rhythmic qualities of language to evoke meaning (linguistics), meanings in addition to, or in ...

, and in the name of the polled Irish Moiled cattle breed. "Muley" derives from Irish and

Scottish Gaelic Scottish Gaelic (, ; Endonym and exonym, endonym: ), also known as Scots Gaelic or simply Gaelic, is a Celtic language native to the Gaels of Scotland. As a member of the Goidelic language, Goidelic branch of Celtic, Scottish Gaelic, alongs ...

''maol'', and Welsh ''moel''.

Genetics

, the polled

allele An allele is a variant of the sequence of nucleotides at a particular location, or Locus (genetics), locus, on a DNA molecule. Alleles can differ at a single position through Single-nucleotide polymorphism, single nucleotide polymorphisms (SNP), ...

is genetically dominant to that for horns. The polled trait is far more common in beef breeds than in dairy breeds.

CRISPR CRISPR (; acronym of clustered regularly interspaced short palindromic repeats) is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. Each sequence within an individual prokaryotic CRISPR is d ...

technology is being developed to create polled versions of dairy breeds. In

, the

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 true breeding polled

goat The goat or domestic goat (''Capra hircus'') is a species of Caprinae, goat-antelope that is mostly kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the ...

s is discouraged as the polled locus is strongly associated with Polled Intersex Syndrome (PIS). Naturally polled

also have genital defects.

Scurs

Naturally polled animals may have

scur A scur is an incompletely developed horn growth. In cattle, scurs are not attached to the skull, whereas horns are attached and have blood vessels and nerves. Scurs may also occur in sheep and goats. Genetic Inheritance The gene for scurs is i ...

s – small, loose, horny growths in the skin where their horns would be. In cattle, this trait has been traced to a separate

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

(on a different

chromosome A chromosome is a package of DNA containing part or all of the genetic material of an organism. In most chromosomes, the very long thin DNA fibers are coated with nucleosome-forming packaging proteins; in eukaryotic cells, the most import ...

) from that responsible for polling. However, the presence of the allele for scurs in cattle can only be seen in a polled animal, because horns replace the scurs in horned animals. Similar scurs may also occur where disbudding of a naturally horned animal has been incomplete.

Reasons for polling

Polled livestock are preferred by many

farmer A farmer is a person engaged in agriculture, raising living organisms for food or raw materials. The term usually applies to people who do some combination of raising field crops, orchards, vineyards, poultry, or other livestock. A farmer ...

s for a variety of reasons, the foremost being that horns can pose a physical danger to humans, other livestock and equipment. Horns may also interfere with equipment used with livestock (such as a

cattle crush A cattle crush (in UK, New Zealand, Ireland, Botswana and Australia), squeeze chute (North America), cattle chute (North America), standing stock, or simply stock (North America, Ireland) is a strongly built stall or cage for holding cattle, ...

), or they may become damaged during handling. In other circumstances, horned animals may be preferred, for example, to help the animal defend itself against

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s, to allow the attachment of head

yoke A yoke is a wooden beam used between a pair of oxen or other animals to enable them to pull together on a load when working in pairs, as oxen usually do; some yokes are fitted to individual animals. There are several types of yoke, used in dif ...

s to draught oxen, to provide a hand-hold on smaller animals such as sheep, or for aesthetic reasons – in some breeds the retention of horns is required for showing. In the US no show requires horns to be left on. Most shows require at a minimum blunting of the horns to a minimum diameter of inch. Boer Goat Shows allow disbudded goats. Dairy breeds of goats are required to be naturally hornless or disbudded. 4H and FFA show goats must be hornless or blunted so as not to be sharp and dangerous.

Development of polled strains

Polled strains have been developed of many cattle breeds which were originally horned. This has usually been done by crossing with naturally polled breeds, most commonly

Angus Angus may refer to: *Angus, Scotland, a council area of Scotland, and formerly a province, sheriffdom, county and district of Scotland * Angus, Canada, a community in Essa, Ontario Animals * Angus cattle, various breeds of beef cattle Media * ...

and

Galloway Galloway ( ; ; ) is a region in southwestern Scotland comprising the counties of Scotland, historic counties of Wigtownshire and Kirkcudbrightshire. It is administered as part of the council areas of Scotland, council area of Dumfries and Gallow ...

cattle. For example, polled

Jersey cattle The Jersey is a British breed of small dairy cattle from Jersey, in the British Channel Islands. It is one of three Channel Island cattle breeds, the others being the Alderney – now extinct – and the Guernsey. The milk is high in butterf ...

originated in

Ohio Ohio ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Erie to the north, Pennsylvania to the east, West Virginia to the southeast, Kentucky to the southwest, Indiana to the ...

sometime prior to 1895. Two strains were developed, the first to appear being founded by crosses of registered Jersey bulls (the standard) on common muley (hornless) cows. These were graded up by the continued use of purebred Jersey sires, selection being made of the polled offspring of each generation, the horned progeny being discarded. Thus originated what was later known as the single-standard strain. As in the case of the Polled Shorthorns and Polled Herefords, the development of the single-standard strain was soon followed by the appearance of a double-standard strain, founded by a few naturally hornless

sports Sport is a physical activity or game, often competitive and organized, that maintains or improves physical ability and skills. Sport may provide enjoyment to participants and entertainment to spectators. The number of participants in ...

that were discovered in registered herds of horned Jersey cattle. These standards were bred among themselves or crossed with registered horned Jerseys, followed by selection for the polled head, and the strain was developed in this way.

References