posted 7 hours ago
This topic needs a bit of introduction - I started raising Native Milking Shorthorns in 2016. This is a rare breed with some outstanding characteristics for homesteaders and I made it my project to create a Landrace of Native MS that are A2/A2 and Homozygous polled. The milk proteins gene comes in several varieties but basically, A1 milk causes a lot of allergy issues, A2 milk not so much. To get A2 milk requires 2 A2 genes. If a cow has 1x A2 gene and 1x A1 gene, the milk will give a mixture of A1 and A2 proteins. To know what genes your cow has, means genetic testing. I use UD Davis genetics lab to get this information. The other characteristic that I am selectively breeding for, is for polled cattle. I don't want horns in my herd for a variety of reasons - mostly to do with nearly losing a eye a few times.
Until a few weeks ago, I was only interested in whether polled animal was heterozygous polled (P/H) or homozygous polled (P/P). Obviously in my project I want to consolidate my breeding program on homozygous polled - though not to the exclusion of all the other great characteristics this breed exhibits. I had a bit of a revelation when the tests from my spring calves came back - one of those calves is homozygous polled, but has two different types of polled gene. I was previously oblivious to the fact that 'polled genes' come in two different flavors. The net effect is the same in that homozygous polled means the cow has no horned gene to give to its babies. When I initially started my project, UCD test results showed only polled versus horned, its only in the last two or three years they started reporting on which polled gene the animal carried.
To some extent, this is an academic discussion - one type of polled doesn't win over the other type of polled - but the origin of the gene comes from two different mutations in separate populations. So all my cattle until 2024 arose from Cantagree and JbarJ bloodlines - and the polled gene contributed from these sources were 100% Pf - that is, all my animals that carried the polled gene, arose from the Friesian mutation/population. Since then, I've bred several animals from the Eionmor Port-O-Call NP bull. His polled gene is of the Celtic variety. So I now have several animals that carry the Pc gene and one special heifer that is homozygous polled with a mix of the two polled genes. Some may find this a boring discussion, but discovering this, I found quite interesting.
Here is the explanation quoted directly from the UC Davis website:
"From the time when livestock was first domesticated, modifications to the wild types have been selected both for animal husbandry and aesthetic reasons. Unique and large horns define cattle breeds such as Texas Longhorn, Highland Cattle, and Ankole Watusi. However, in modern times many cattle are maintained in more crowded conditions such as barns and small fenced pastures where polled phenotypes are more desirable for both beef and dairy breeds.
Recently, candidate mutations associated with polled phenotype in European breeds of cattle were found. There are 2 independent origins of polled, one found in Holstein-Friesian and Jersey breeds (Pf), the other in many European breeds of Celtic origin (Pc) such as Angus, Blonde d’Aquitaine, Dexter, Limousin, Charolais, and Hereford, among others. Investigation of the polled mutation in Brahman cattle revealed the segregation of the Celtic polled variant (Pc) in the breed. Polledness is dominant; a polled animal can have one or two copies of the polled alleles. All offspring of a homozygous polled bull (2 of the same polled allele, Pc/Pc or Pf/Pf) will be polled. Additionally, offspring with one copy of each of the polled alleles (Pc/Pf, compound heterozygous) will also be polled. Genetic testing is a cost-effective means to determine if a polled animal has 1 or 2 copies of the polled alleles.
Testing for the polled gene assists breeders in selecting cattle that have 2 copies of Polled gene."
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