Bovine Polled Phenotype

[Donlin Stud]

Research is slowly uncovering how the Polled mutation does influence the phenotype other than not growing horns


Visual examination of 166 horned and 78 polled animals confirmed a perfect association between polledness (whether of Celtic or Friesian origin) and an atypical eyelash-and-eyelid phenotype, thus revealing that the Polled locus does not only affect horn ontogenesis.

In most cases, this phenotype was characterized by accessory rows of eyelashes and eyelid hypertrichosis, with additional hair showing unequal length, irregular orientation and darker coloration in pigmented animals (Figs. 3A–3C). In rare cases (less than 10%), the abnormal phenotype was milder and either restricted to additional rows of eyelashes of normal length (Fig. 3D) or to a single row of eyelashes with irregular hair length (not shown). No notable difference was found between Celtic or Friesian polled animals, indicating that both mutations have exactly the same phenotypic consequences.

CopiedfromthewebsiteResearchpaper here

[cascade]

Most all genes have multiple effects.

I'm certainly happy to hear that polled animals have extra good eyelashes and extra pigment to protect from dust and sun.

[jamshundred]

And the genetic defects in the reproductive organs of bulls?

AND.......unless there is parentage confirmed for two generations it is more likely an outcrossing than a mutation.

[cascade]

The link to the study that Donlin so thoughtfully provided up top, proved that there is no direct linkage of the polled gene to male reproductive tract features.

"none of the other Celtic polled, Friesian polled animals examined showed similar symptoms [of the reproductive tract], indicating that this phenotype, which is consistent with the absence of the retractor muscle of the prepuce previously reported in PC/PC Galloway and Aberdeen-Angus bulls [31], is not completely associated with the Celtic mutation. It is more likely specified by another locus in moderate linkage disequilibrium with the Celtic mutation or by other breed-specific loci interacting with the Polled loci."

This is similar to the dun gene interacting with the black gene. The black gene isn't the "cause" of dun, but the black gene helps dun genes exhibit. Similarly, the polled gene doesn't cause any male reproductive tract anomalies, but the polled gene helps uncover those other problem genes when they exist so they can be culled. That's why there are so very many polled bulls with perfect male reproductive organs.

Additionally, it only takes a single generation to prove a mutation. If you have two DNA-tested horned animals and they give parentage-verified birth to a DNA-tested polled calf, that's immediate proof of a polled mutation.

[lonecowhand]

Funny that you should suddenly be in agreement that "Most all genes have multiple effects" .

You have been denying that fact for years, all those denials are recorded here, insisting that the only effect from the polled outcrossing of Saltaire Platinum into the Dexter breed was the lack of horns.

I don't know that anyone cares about eyelashes,but there will be other provable genetic modifications as the science catches up with observation.

Hogwash.

[jamshundred]

I beg to differ.  I have seen a modern study that said there ARE genital defects in polled cattle.

I also found it interesting that not only have Dexters with  Friesien and Celtic polled been tested, but apparently there has been found polledness not of those two types.   How very interesting.  

Perhaps Lakeport is not only a tad suspicious but prescient as well.  

[cascade]

Yes, most all genes have a primary effect along with some other minor effects. That's true of the dun gene too. In the case of the polled gene, the minor effect of extra good eyelashes is an effect caused by the polled gene.

If a fresh polled mutation occurred​ in a "Legacy" Dexter, it too would have extra good eyelashes.

You guys would try to say that the extra-good eyelashes "came from another breed", but they don't. The eyelashes are an effect of the polled gene.

My point is that other genes can't tag along with the polled gene through the generations. Mendel's law of independent assortment prevents that. Even if the polled gene came in via an introgression, no other genes could easily tag along for the ride, unless someone specifically selected for those other genes.

[cascade]

Yes, some horned cattle have genital defects and some polled cattle have genital defects, but this study proved that the polled gene itself does not create genital defects.