Cattle genetics 101

[Brandonm22]

My Grandfather always claimed that if an animal was scurred then you knew she was a horn carrier. I don't know where he got his information.

 

[dun]

You'll have to live with the simple genetic resaerch that says scurs and horns aren;t related. If an animal is horned the area that the scurs would be formed are overgrown by the horn. If an animal is dehorned/disbudded, the part of the hide that would grow the scurs is removed so it appears to be non-scurred. I'll agree that the total understanding of scurs isn;t very good. Years ago we used an old line of linebred Angus bulls on Holtein heifers. I don;t know how the bull calves turned out becuase they were shipped at 8-10 weeks. Most of the heifers were scurred.

 

[hillsdown]

The scurred gene still baffles me. My main clean up bull (Big Gun) is scurred, he is out of a scurred cow and polled bull. All of his calves born this year were polled with two bred cows being horned holsteins and one being a horned gelbstein..Of the cows that gave me polled calves some of them had given me horned calves in previous years after being bred to a polled bull.

Big Gun's dam was AI'd to a polled bull last year and she gave me twins this year, one is polled and one is scurred..Her dam has not had a scurred or horned calf since and she had her 6th calf this year.

 

[alexfarms]

I have had numerous Angus breeders tell me that scurred animals don't necessarily carry the horned gene. Maybe that is true in the Angus breed, but I doubt it. The old American Polled Hereford Association had a Superior Sire Program in which bulls were genetically tested in various ways and one of the qualifications for becoming a Superior Sire was the bull had to be proven to be a 100% dehorner through matings to horned cows. In the history of the Superior Sire Program not one scurred bull tested was proven to be a 100% dehorner. I have made this challenge before and no one has ever answered it YET: Tell me one scurred bull that has been PROVEN to be a non-carrier of the horned gene. In most breeds scurred bulls are discarded, but in the old APHA some top notch scurred bulls were tested, if they weren't top bulls they probably would never have been kept...So please don't start the argument about "scurrs are a sign of superiority". IF someone can tell me of a proven 100% dehorner that is scurred, then I will start to believe the notion that there is no linkage between the presence of scurrs and the presence of the horned gene. With the current dna tests for horns, it looks to me like a 100% dehorning, scurred bull ought to have been identified.

I've tried in vain to get factually correct information on scurs, most of the research is quite old and not a single paper came to a concise answer. For a long time I believed the sex linkage to be correct, but that has recently been proved wrong in my herd or atleast not exactly correct. A smooth polled cow had a lightly scurred heifer and a smooth polled bull calf the next year, if the sex linkage was correct the bullcalf must have atleast one scurred allel and should have been scurred.

I am currently doing an experiment in a neighbours herd of mostly horned herefords and some of my polled bulls. So far a scurred bull has sired about 60% horned calves and not a single scurred calf. A smooth polled bull has sired 100% polled, but its still too early to tell with certainty whether he sired some scurs or not. Previously I've used homozygous polled bulls that never sired a scurred calf, hopefully this bull at the neighbours will also do this to atleast give me a better indication what to expect as far as scurs go in homozygous polled bulls.

For the time being I have seen nothing that has proved my theory, of all scurred bulls are heterozygous, wrong.

There was an article in a Polled Hereford World in the 1970's that claimed the scurred gene was both sex linked and linked to the horned gene. It went something like: If a bull calf carried the horned gene and 1 or both scurred gene he would be scurred. If a heifer calf carred a horned gene and 1 scurred she would be smooth. If a heifer calf carried the horned gene and 2 scurred genes she would be scurred. So, in bull calves carrying the horned gene and a scurred gene, the scurred gene was dominant and in heifer calves the scurred gene was always recessive and neither bulls nor heifers would be scurred unless they carried the horned gene. You state that you have used a homozygous polled bull that never sired a scurred calf. How many horned cows did you breed that bull to? It is tough to get a smooth polled bull calf from a horned cow. I have gotten some, but not many. I have had horned cows that NEVER produced a smooth polled bull(they have produced heifers) when bred to polled bulls several years. I was pretty confident that the 1970's article was an accurate description of the way the scurred gene acted in our herd, but there have been instances where I doubted it also and the Angus guys will swear it's not accurate. Right now, I don't recall the specific instances where it didn't seem to fit in my own experience. I can confidently tell anyone that if they want to find out how many of their cows carry the scurred gene, breed them all to a horned bull and you'll have more scurrs than you would ever dream possible.

 

[bigag03]

With Hereford cattle, I believe the 1970's article is accurate. The expression of scurs is controlled by the horn gene. The degree of expression is controlled by separate genes (these are the ones that are largely unkown). The problem comes when you insert Bos indicus influence. Problems with tracing the inheritance of horns/scurs in these cattle has always been blamed on the African Horn gene. That assumption is probably correct, but no one has been able to find this allusive gene yet or even completely understand its mode of inheritance.

 

[randiliana]

The way I learned it, there is a difference between incomplete dominance, and co-dominance.

With incomplete dominance, you have

RR being red
WW being white and
RW results in PINK

With co-dominance, you have

RR being red
WW being white and
RW being both red and white ie ROAN

However, there are exceptions to the way heterozygotes express themselves in the phenotype. One exception is incomplete dominance (sometimes called blending inheritance) when alleles blend their traits in the phenotype. An example of this would be seen if, when crossing Antirrhinums—flowers with incompletely dominant "red" and "white" alleles for petal color—the resulting offspring had pink petals. Another exception is co-dominance, where both alleles are active and both traits are expressed at the same time; for example, both red and white petals in the same bloom or red and white flowers on the same plant. Codominance is also apparent in human blood types. A person with one "A" blood type allele and one "B" blood type allele would have a blood type of "AB".

Co-dominant/Incomplete Dominant: The heterozygous genotype is a visible mutant phenotype but the homozygous genotype is a different visible mutant phenotype.

I finally had time to look this up, I had just taken for granted that what the articles said was true. Most of what I found treats co-dominace and incomplete dominance as different terms for the same trait. They seem to be pretty interchangable, but in the few instances where they defined them separately, you guys seem to be correct.

 

[Jovid]

You all are wearing me out on this hide color and horn thing.

If you raised Red Polls you wouldn't have to worry about either one. All of them woul be red and they would be polled.

 

[dun]

You all are wearing me out on this hide color and horn thing.

If you raised Red Polls you wouldn't have to worry about either one. All of them woul be red and they would be polled.

Same with Red Angus

 

[brandonm_13]

Same with Longhorns. Wait. That can't be right. :???:

 

[ANAZAZI]

The easiest way to get rid of scurs is to avoid scurred bulls; because in the long run this practice will make scurs virtually extinct without us knowing how it is inherited!