Polled cattle are born naturally without horns. They are not animals that had their horns removed. The hornless trait is written into their DNA and passes to their calves, which is why breeders list it as a trait on bull sheets and sale ads. In many beef breeds such as Angus it is the norm, while most dairy cattle still carry horns.1International Milk Genomics Consortium. Genetic Editing Eliminates Dairy Cattle Horns, AKA Dehorning For many farmers, choosing polled genetics is a way to skip dehorning entirely, and the gains in welfare, safety and carcass value come with no measured loss in milk, fertility or longevity. The main catch is in dairy breeds, where breeding for polled currently means fewer bull choices and slower genetic progress.
How Polled Cattle Lose Their Horns Before Birth
Horns start in the womb. In horned calves, horn buds and small dents in the skin are already visible about 58 days into pregnancy.2PubMed Central. The Development of Horns in Bovidae and the Genetic Mechanisms Underpinning This Process In polled fetuses those buds never form at all.3PubMed. Understanding the effects of the bovine POLLED variants The polled change seems to switch down the genes that would otherwise build the horn bud.4PubMed. Understanding the effects of the bovine POLLED variants
There is more than one polled version. Polledness traces back to at least four separate natural DNA changes in European-type cattle, including the Celtic and Friesian versions.5PubMed Central. The Development of Horns in Bovidae and the Genetic Mechanisms Underpinning This Process The Celtic version is common in beef breeds such as Angus, while the Friesian version arose in Holstein-Friesian dairy cattle.6PubMed Central. Bovine Polledness – An Autosomal Dominant Trait with Allelic Heterogeneity7PubMed Central. The 80-kb DNA duplication on BTA1 is the only remaining candidate mutation for the polled phenotype of Friesian origin The Nellore breed carries yet another version.8PubMed Central. The Development of Horns in Bovidae and the Genetic Mechanisms Underpinning This Process So different breeds can be polled for different underlying reasons, which matters when you order a genetic test.
Sale listings use several words that sound alike. Polled means born hornless and able to pass that on to calves. Dehorned or disbudded animals still carry horn genes and can sire horned calves, and a smooth head alone doesn’t tell you which one you’re buying. Ask for the genetic test result or the registration papers.
How Polledness Is Inherited
The polled variant is dominant over the horned version, so one copy from either parent prevents horns.9International Milk Genomics Consortium. Genetic Editing Eliminates Dairy Cattle Horns, AKA Dehorning That means a one-copy polled animal, written Pp, looks just as hornless as a two-copy polled animal, written PP. The difference shows up in the calves. A horned animal is written pp.
The common matings work out like this:
- PP bull or cow, any partner: every calf is polled.
- Pp × horned (pp): about half polled, half horned.
- Pp × Pp: about three in four polled and one in four horned, with one in four of all calves PP.
- Horned × horned: all horned.
PP bulls usually cost more. If you never want to disbud again, pick PP.
A one-copy bull is a gamble on each calf, because each calf independently gets either his polled copy or his horned copy. A small herd with only a few calves a year can see odd runs, such as four horned calves in a row from a Pp bull, without anything being wrong. The half-and-half ratio only shows up over many calves. If you only keep a bull for a season or two, the higher price of a PP bull buys certainty that you won’t be disbudding any of his calves.
You can also convert a horned herd over generations. A first cross of horned cows with a PP bull gives all Pp calves. Keeping Pp heifers and using PP bulls on them makes some PP daughters. Horned calves stop appearing once no horned copies remain in the herd.
How common polled is depends on breed. Fewer than 3 in 100 copies of this gene in US dairy cattle are the polled version,10PubMed Central. Comparison of Gene Editing Versus Conventional Breeding to Introgress the POLLED Allele Into the Tropically Adapted Australian Beef Cattle Population while in Australian Brahman cattle it’s about 20 in 100.11PubMed Central. Comparison of Gene Editing Versus Conventional Breeding to Introgress the POLLED Allele Into the Tropically Adapted Australian Beef Cattle Population Dairy farmers therefore have far fewer polled bulls to choose from than many beef farmers.
Scurs and Why Some Polled Cattle Grow Them
Some polled animals grow small horny bits on the head anyway. These are called scurs: growths not firmly attached to the skull, ranging from bumps and scabs to growths up to about 10 cm.
They show up only in one-copy polled cattle. In one large group of Holsteins, all 207 scurred animals were one-copy polled and none of 191 two-copy polled animals had scurs.12PubMed Central. Independent Polled Mutations Leading to Complex Gene Expression Differences in Cattle In Canadian beef cattle all 153 scurred animals were one-copy polled.13Canadian Journal of Animal Science. Heterozygosity of the Celtic polled locus in Canadian scurred beef cattle A scurred animal is a strong sign it is Pp, not PP.
Sex matters too. Scurs are influenced by sex and appear more often in bulls.14Canadian Journal of Animal Science. Heterozygosity of the Celtic polled locus in Canadian scurred beef cattle A separate scurs gene acts on top of the polled one.15PubMed Central. The scurs inheritance: new insights from the French Charolais breed Even males carrying it don’t always show scurs; in French Charolais only about 40% did.16PubMed Central. The scurs inheritance: new insights from the French Charolais breed So you can’t rule out carrying scurs genetics by looks alone.
Scurs rarely need removal unless they curl into the head. They do not mean the animal is horned, so check before culling a polled breeding animal.
On a live animal, the loose attachment is the giveaway. Scurs can wobble or shift when pressed, whereas a true horn is firmly fixed to the skull and grows from the bud site. Scurs often show up later than horns would, months into a young animal’s life, so a calf that looks smooth at first can still develop them. They can be a small scabby lump, a short stub, or a thin growth that bends, and they vary a lot even between animals in the same herd.
The Welfare Case Against Disbudding
Disbudding removes a calf’s horn buds, usually with a hot iron or caustic paste. Afterward, calves shake their heads, flick their ears and scratch more for several hours, and they play less.17PubMed Central. Multi-dimensional evaluation of pain response in low day-age calves to two types of dehorning Calves treated with caustic paste showed raised stress hormone for up to 7 hours.18PubMed Central. Multi-dimensional evaluation of pain response in low day-age calves to two types of dehorning
Pain relief helps. A local anaesthetic plus an anti-inflammatory painkiller clearly reduces pain behaviour and stress.19PubMed. Graduate Student Literature Review: Role of pain mitigation on the welfare of dairy calves undergoing disbudding If you do disbud, ask your vet for both. The anti-inflammatory matters because pain and head shaking continue for hours after the numbing wears off. Polled calves have no buds to remove, so there is no procedure, no recovery and no painkiller cost.
Safety and Handling Advantages
Farmers feel horns make an animal more dangerous even when it isn’t aggressive.20PubMed Central. Human–Animal Interactions with Bos taurus Cattle and Their Impacts on On-Farm Safety: A Systematic Review Hornless cattle cut injury from human-cattle encounters,21PubMed Central. Human–Animal Interactions with Bos taurus Cattle and Their Impacts on On-Farm Safety: A Systematic Review and dehorning is recommended to help prevent workplace deaths from cattle.22Journal of Agromedicine. Nonvenomous Animal-Related Fatalities in the United States Workplace, 1992-1994 Hornless cattle are also safer around other livestock and farm dogs.23PubMed Central. Attitudes Towards Animals and Calf Disbudding Techniques: A Mixed Methods Study Using the Animal Attitude Scale (AAS-10)
Between cattle, horns can gore or bruise herdmates during normal pushing and jostling, even when no animal is fighting. Lower-ranking cows are most at risk, since they are often shoved aside and can be hit while moving away.
Space is another gain. Polled cattle need less room at the feed bunk, which reduces competition,24PubMed Central. Attitudes Towards Animals and Calf Disbudding Techniques: A Mixed Methods Study Using the Animal Attitude Scale (AAS-10) and they take up less trailer space in transport.25PubMed Central. Attitudes Towards Animals and Calf Disbudding Techniques: A Mixed Methods Study Using the Animal Attitude Scale (AAS-10)
Fewer Bruises and Better Carcass Value
Truckloads containing horned cattle had about 65% more carcass bruising than polled loads, and about 1.1 kg more meat was trimmed per carcass.26Semina: Ciências Agrárias. Genetic group and horns presence in bruises and economic losses in cattle carcasses All-horned loads had several times higher odds of carcass injury than polled loads,27Ciência Animal Brasileira. Longitudinal analysis of pre-slaughter factors influencing the incidence of injuries in beef carcasses and even mixing a few horned animals in more than doubled the odds.28Ciência Animal Brasileira. Longitudinal analysis of pre-slaughter factors influencing the incidence of injuries in beef carcasses If you ship both, keep horned and polled animals apart.
Most bruising happens when cattle are crowded together, such as in the pen, on the truck and in holding pens at the abattoir. Horns do the most damage in these moments because animals cannot get away from each other.
Does Polled Affect Milk, Fertility or Longevity
In US Brown Swiss, Holstein and Jersey cows, polled genetics had no effect on milk, fat or protein yield, fertility or herd life.29PubMed. Short communication: Phenotypic and genetic effects of the polled haplotype on yield, longevity, and fertility in US Brown Swiss, Holstein, and Jersey cattle German Simmental studies found no effect on milk, udder health or fertility.30PubMed Central. A variance component estimation approach to infer associations between Mendelian polledness and quantitative production and female fertility traits in German Simmental cattle
The real cost is choice. Fewer top-ranked polled dairy bulls exist, so choosing polled over horned can mean slower genetic gain in the short term.31PubMed. Short communication: Phenotypic and genetic effects of the polled haplotype on yield, longevity, and fertility in US Brown Swiss, Holstein, and Jersey cattle Many two-copy polled Holstein bulls born in 2012-2014 descended from the same two founder bulls.32Livestock Science. Breeding for polledness in Holstein cattle Relying only on two-copy polled bulls could push dairy inbreeding to about 17% versus under 7% normally.33PubMed. Comparison of gene editing versus conventional breeding to introgress the POLLED allele into the US dairy cattle population Check inbreeding figures before buying polled semen.
You can balance polled against other traits. Using Pp bulls with strong merit widens your choice, and rotating unrelated polled sires keeps relatedness down. Beef breeds face this problem less, since polled is already common there.
Is Breeding for Polled Cheaper Than Dehorning
Traditional dehorning costs about $6 to $25 per dairy calf, averaging $12-13.34PubMed. Economic considerations of breeding for polled dairy cows versus dehorning in the United States A US dairy farmer can pay up to about $2 more per straw for one-copy polled semen, or about $4 for two-copy, and still break even.35PubMed. Economic considerations of breeding for polled dairy cows versus dehorning in the United States In Brazilian Nelore beef cattle, breeding for polled beat disbudding on cost.36PubMed. Economic considerations of breeding for polledness versus disbudding in beef cattle
To run the numbers for your herd, start with your actual cost per calf for disbudding, including drugs, supplies and your own time. Compare that against the extra price per straw or per bull for polled genetics, spread over the calves you expect.
How to Test Whether an Animal Is Truly Polled
Current DNA tests sort animals into horned, one-copy or two-copy polled and identify Celtic or Friesian versions.37PubMed Central. Optimized Genetic Testing for Polledness in Multiple Breeds of Cattle An improved test gave a result for about 99.96% of samples.38PubMed Central. Optimized Genetic Testing for Polledness in Multiple Breeds of Cattle Some older tests give no result when uncertain, such as Australia’s test below 90% confidence.39Proceedings of the World Congress on Genetics Applied to Livestock Production. Current status of Australia’s diagnostic poll haplotype test Retest an animal that comes back with no result.
To test, pull tail hair with the roots or use a blood card, then send it through your breed association or a lab. Results list PP, Pp or pp. Test bulls before buying, since looks don’t reveal PP.
Gene-Edited Polled Cattle
Gene editing can give dairy cattle the same polled version Angus carry naturally.40International Milk Genomics Consortium. Genetic Editing Eliminates Dairy Cattle Horns, AKA Dehorning A simple small DNA cut alone did not stop horn buds forming,41PubMed Central. A deletion at the polled PC locus alone is not sufficient to cause a polled phenotype in cattle so the edit copies the natural change instead. US regulators found four edited polled bulls grew and stayed as healthy as normal calves.42U.S. Food and Drug Administration. Risk Assessment Summary: Heritable insertion of the Celtic allele in cattle (Bos taurus) Edited polled bulls pass polled on like natural ones.
Conventional breeding mixes whole genomes, so adding polled from one bull also brings along his other genes, good and bad. Editing changes only the target spot, so a top horned bull could be given the polled change while keeping the rest of his genetics. This keeps inbreeding lower.43PubMed. Comparison of gene editing versus conventional breeding to introgress the POLLED allele into the US dairy cattle population
For an ordinary farmer now, edited animals are rare and regulated, and conventional polled bulls remain the practical option.