Polled Animals

[Mark S]

I have just looked at the Cattle for Sale and noticed that Apple Lancelot is being sold as a 'Polled Bull'. The picture clearly shows evidence of horn. This bull might well carry the polled gene however to sell him as a polled bull will cause confusion to some breeders (see replies to Monica's entry re polled bull). Should this advert be amended ? and should a description of the definition of what is a polled animal be published in the bulletin.

Mark S

Brereton Herd

[Mark Bowles]

Very good point Mark, i let that one slip through, i will amend it. Thanks for your sharpe eye!

[Colin]

The advert says the horns are loose, which would indicate they are not true horns but scurs which is a different gene I believe. So he could well be polled.

Regards,

Colin

[monica a waltho]

Glad you brought this up Mark as couldn't agree more that something needs to be done to educate members to understand what is polled/dehorned as there seems to be alot of confusion out there.Perhaps an article in bulletein or something on the Society website would be a good idea with pictures.I also saw the bull and thought he's not polled but reading the rest of description about loose horns does this mean they are scurs (to big surely) or are they whats grown after dehorning? Dexters are not the easiet breed to dehorn sucessfully sometimes.
Perhaps his breeder could tell us.

[monica a waltho]

Just recieved a reply from someone who has advertised a bull on another site who described him as polled but from his picture looked as if he had been dehorned so I asked the question to which the reply was he had been dehorned.
Does any one think the online form doesn't help members as on the bit requarding horns you have a choice between horned or polled which can lead to confusion I think. When i first started using online registration i did query it with secretary as i was concerned it would be in herdbook and on ped certificate as horned as I didnt want that because they would be dehorned if you tick polled it appears on /in both. From what i remember of conversation I was told to put them down as horned even if they would be dehorned at later date and any natuarally polled animals to put as polled because this is what they were born as which is what i do. But if people dont ask they could get confused i think
When you fill in about sex of animal we have a choice of male, castrate or female would it not be better to have Naturally polled, horned or dehorned OR just Naturally Polled

How many cattle I wonder are in herd book as polled when in fact they have been dehorned.

When I first bought Dexters I learnt to ask whether they had horns or been dehorned as often they had horns which is fine if thats what you want the polled issue never arose because they were few about andfrowned upon. Still are by some I know

[Broomcroft]

According to my dictionary, "polled", when referring to cattle just means without horns, whether they were born polled or whether the horns were removed.

I have an Angus cross with very visible scurs. He's naturally polled though.

[Adam Lowline]

Really interested to read the discussion, I had always assumed that "polled" meant naturally born without any horns. But I now know differently, we have just had two calfs, one dexter is naturally polled, the other is just showing some "buds", the bulls were Lowlines, which are naturally polled always, so it will be interesting to see whether both calfs have the naturally polled gene.
Anyone have any ideas or guesses?
Will keep you posted
Adam

[Colin]

If Lowlines are always naturally polled then I would say they will be homozygous polled and will not carry the horned gene. In which case they will always pass on the naturally polled gene. Here's some useful information from Kirk in a thread of a few years ago:

Unread postby Kirk- Cascade Herd US » Sun Oct 07, 2007 4:46 am

Colin wrote:Kirk I found your information excellent. I've not got into the genetics of colour yet so this is an invaluable summary. Where can I get further information on the genetics of naturally polled and horned animals. ? I have a bull from a naturally polled farther and a horned mother. He seems to be a combination, no apparent horn buds initially, but then developed some horny stumps, which have since been removed.

Colin


In cattle, there are likely two primary loci (locations on the DNA chromosomes) that control horns and scurs. At the horned/polled locus, there are two choices, P (dominant polled) and p (recessive non-polled). An animal inherits one of these from each parent:

Here are the 3 possible combinations:

P/P (Homozygous Polled - a polled gene from each parent)
P/p (Heterozygous Polled - one of each gene)
p/p (Horned - two horn genes required to be horned)

A homozygously polled animal always contributes a polled gene and always has polled calves even when bred exclusively to horned animals. A horned animal always contributes a horned gene, but if the other parent contributes a polled gene, then the calf will be polled since polled is dominant. Two heterozygously polled animals can have a mix of both polled and horned calves. One heterozygously polled animal and one horned animal can also have a mix of horned and polled calves. Horned animals cannot "carry" polled genetics because polling is dominant, but polled animals can carry hidden (recessive) horned genes.

Scurs are a type of horn growth that produces small stumpy false horns (sometimes much larger) that are generally loose and not attached to the scull (but may attach in older animals). A polled animal with scur genes may grow these scurs. A horned animal with scur genes cannot exhibit scurs because the horns override the scurs. There are two alternative choices (alleles) at the scur locus: Sc (scurs) and Sn (no scurs). An animal inherits one of these two alternatives (alleles) from each parent. There are 3 possible combinations:

Sn/Sn
Sn/Sc
Sc/Sc

Scur genetics are complex and are influenced by the sex of the animal. The scur gene is dominant in bulls and recessive in cows. So, it takes two Sc genes for a cow to have scurs, but it only takes one Sc gene for a bull to have scurs. Further, the exhibition of scurs also is influenced by the number of polled genes that the polled animal has; one or two. A polled bull with one polled gene and one scur gene will likely have scurs, but a homozygously polled bull (with 2 polled genes) will likely require two scur genes in order to exhibit scurs. A polled cow with one polled gene requires two scur genes to exhibit scurs, but a homozygously polled cow with two scur genes will likely be smooth headed.

Further complicating this are genes that alter the size and growth of scurs, making them larger or smaller.

Hope this helps,

Kirk

[Broomcroft]

To me and I think most cattle breeders, polled means naturally polled. I was just quoting what my dictionary says about the word polled. But assuming my dictionary is correct, then just using the word polled will never work to describe genetically or naturally polled.

Because they seem to do a lot more crossing in America, I asked on the American Dexter forum about what would happen when I put my Angus-Dexter crosses back to a genetically-horned Dexter bull. Here's one of the answers which I thought was quite interesting.

"Clive, polled is dominant, and your Angus bull has both genes for polled, no horned genes. That means that every calf born of him will be polled. Since the dams were horned, it means that none of them has a polled gene, therefore all of their calves will receive a horned gene from their dam and a polled gene from their sire.

Not all polled cattle have two polled genes, but Angus cattle do. Any bovine with a single polled gene will be polled. There is no DNA test for this, no way to be 100% sure whether a polled bovine carries one or two polled genes. It's important to know, for the reasons you want to know.

Putting a horned bull over your crossbred heifers will get a mixed lot of calves, some polled, some horned.

Putting a polled bull over them, the results will vary depending upon whether he carries both polled genes (all calves will be polled) or one polled gene (mixed results).

What you need to help you accomplish your goal is a homozygous polled, Ed/Ed B/B bull. Ed/Ed means he's all black. B/B means he doesn't carry dun.

None of your polled crossbreeds are homo polled, so you're not going to find a bull like that among them, but breeding your crossbred heifers back to your Angus bull could net a few. You'd just have to identify them.

The Angus breed has a DNA test which is an indicator of whether the animal is homozygous polled. It's not a definite test for polledness and it's not for other breeds. It may give you a good idea which of your second-generation crossbred bulls is homo polled, since they will be 3/4 Angus. That could help you pick one to keep.

No one has yet found the gene for polledness, so all the DNA tests they're selling actually test other things and try to predict whether the animal is homo polled. Performance is the indicator that is most often used for polledness. If a bull has a jillion calves out of horned cows, and every one is polled, he's homo polled. One horned calf and he's not homo polled."

I think what this means basically is that once you've crossed an Angus (and I assume a Lowline would be the same) with a horned breed, then you've introduced the horn gene back into the breeding, although if you use a "fully" polled bull all the time (Angus/Lowline), then you'll never see any horns because polled is dominant. But the horned gene could still be carried in the polled offspring. Hope I got that right!

We've had 3 Angus-Dexter crosses with scurs.

[Inger]

Clive, I don't think the colour of the animal has any bearing on the horn or poll genes of the animal. If the animal has 1 poll gene, it won't grow horns. As the poll gene prevents any horn growth. If the second gene is for horns, then it can of course, pass on that horn gene to it's offspring.

Scurs can only show up, if there are no horns to over-ride the appearance of scurs.

The genetics of inheritance is different in sheep than in cattle, so it can be rather confusing. Goats have different dominant genetics again.

[Broomcroft]

Hi Inger, Yes, it reads a bit funny because I only posted the response to my question, not the question itself which was about colour and polled, but not linked.