double spur

[Perris]

If multiple spurs are dominant, as per https://sellers.kippenjungle.nl/page3.html , can anyone please explain how I have got a 3rd generation roo expressing it, when none of his ancestors presented it?

On a separate note, growing these over the last few months does explain why he's been helping himself to oyster shell as much as the hens normally do.

 

[Amer]

Multiple spurs is dominant but I believe that a double spur is a recessive trait.

 

[Skyle]

Multiple spurs (M) is incompletely dominant, a M/m+ bird usually grows only two spurs, while a M/M one could grow more.
Maybe this trait was carried by hens, so it wasn't as much noticeable? Sometimes roosters which have multiple spurs would grow a large one and, then, the other (or others) would remain much smaller, almost un-noticeable if you don't pay much attention.

There are two more genes that "give" more spurs:
Auxiliary spurs (As), it's completely dominant and birds who have it would grow a small spur (about half an inch long or a little more) above the main one.

Then, there is double spur (ds), which is recessive and chickens who have it would grow two spurs. It's not always shown in males.

 

[CombNWattles]

You should enter this guy in my spur contest!

https://www.backyardchickens.com/threads/spur-contest-ends-january-11-2025.1648023/#post-28259761

 

[chickyturkeyemulady]

I just lost my 10 year old SLW too that had a double spur on one leg. He was 3rd generation. I have his 5 year old son. None of the others, including sibs that were either sold or processed had multiple spurs.

 

[Perris]

@Amer and @Skyle can you please point me in the direction of some source(s) where recessive ds gene is explained? Is it possible or even likely that his dam was the carrier?

 

[Amer]

I actually said "I believe" because it was totally a guess based on experience. I wasn't aware that there was a specific gene but Double spur is a common recessive "trait" that I see in pure breeds. Since it is a defect in the SOP, breeders would quickly breed away from it if it is dominant (though females with this trait would be easy to miss.) However, a recessive trait would be much harder to eliminate which is why I sometimes see it.
I do believe Skyle if she says there is a recessive spurs gene.
If it is recessive, both parents are carriers of the gene.

 

[Skyle]

@Amer and @Skyle can you please point me in the direction of some source(s) where recessive ds gene is explained? Is it possible or even likely that his dam was the carrier?

Sure, this source is in italian though: Summagallicana. It explains briefly the genes that I listed and much more, it's a very good source for genetics learning. The recessive spur gene is at chapter 5.4.
@Amer is right, if the spurs of this rooster are caused by the recessive gene, both his parents must have carried it.