Horny Question

Sylvia · Post by **Sylvia** » Fri May 11, 2007 4:37 pm

Well I never, you live and learn. So why do wethered Shetland ram lambs not grow horns and Dexter steers do?

Kirk- Cascade Herd US · Sat May 12, 2007 6:10 am

Sylvia wrote:So why do wethered Shetland ram lambs not grow horns and Dexter steers do?

We have Icelandic Sheep, very similar to Shetland sheep, but much larger. In these sheep, rams with two horned genes and no polled genes are born with large horn buds that rapidly grow into massive triangular spiral true horns. Rams with one polled gene and one horned gene are born without large horn buds, but will more slowly grow smaller rounder spiral horns (not the massive true horns). Ewes with one polled gene and one horned gene will usually be hornless, presumably due to a lack of male hormones. So, as in ewes, perhaps a wethered heterozygously polled ram lacks the hormones needed to grow these round spiral horns that would grow if he wasn't wethered at an early age.

Cattle horned/polled genetics work differently. A heterozygously polled bull won't grow horns at all, with or without male hormones and a steer with two horned genes will grow horns, just as a wethered sheep with two horned genes will grow horns.

Hope this helps.

Kirk

Inger · Post by **Inger** » Sat May 12, 2007 12:27 pm

In the reading I have done on the internet, the researcher said that they hadn't found a case of a homozygously polled bull with scurs. They were all Heterozygously polled. But I guess, just because they hadn't found any cases, doesn't mean its impossible, just that their sample base might not have been big enough?

Kirk- Cascade Herd US · Sat May 12, 2007 8:33 pm

Inger wrote:In the reading I have done on the internet, the researcher said that they hadn't found a case of a homozygously polled bull with scurs. They were all Heterozygously polled. But I guess, just because they hadn't found any cases, doesn't mean its impossible, just that their sample base might not have been big enough?

It is my understanding that for a homozygously polled bull to have scurs, it also needs to have two scur genes and no other modifier genes that would hide the scurs. It would probably be pretty rare to find a bull that is both homozygously polled and homozygously scurred, especially since most breeders try to eliminate any scur genes. So I suppose their sample would need to be extremely large to find such a bull.

Here's a link to an article that supports this idea:

Inheritance of Horns and Scurs