DDC

[Rniemann]

What is this genetic deform and how serious is it? Any others to look out for in angus?

 

[boondocks]

What is this genetic deform and how serious is it? Any others to look out for in angus?

Here's the AAA fact sheet on developmental duplication ("DD"): http://www.angus.org/pub/DD/DDFactSheet.pdf

The "C" simply means the animal is a carrier for that mutation. It's a pretty common genetic defect--traces back to a bloodline that was used a lot, before testing became available fairly recently. If you have an animal that's a carrier ("DDC"), don't breed it to another carrier and you're fine.

Another symbol to look for is "DDP"--that means that based on its lineage, the animal could be a DD carrier (P=Potential), but has not been genetically tested yet. The animal's registration papers will bear that DDP legend until the animal is tested (at which point the legend will be changed to reflect the actual status). We ended up with a couple carriers; they look, and are, fine; we just need to not breed them to another carrier, is all. (The blood test is simple; let me know if you need a link.)

Other defects of interest are NH and CA; here are their fact sheets: http://www.angus.org/pub/CA/CAFactSheet.pdf http://www.angus.org/Pub/NH/NHFactSheet.pdf
Someone more of an expert than me (wouldn't be hard!) will, I'm sure, chime in, but my understanding is that most if not all of these defects are found in many other breeds as well. Genetic "defects" have always been with us; we just have an increasing ability to test for them. (Lack of genetic diversity in a population can magnify the problem, in my understanding).

 

[Katpau]

Below are descriptions of the most common defects identified in Angus cattle. Some or all of them may also be present in other breeds of cattle. Carriers of these defects can be identified with a blood test. They are simple recessives, and the calf must receive the gene from both parents in order to be expressed. When you breed two carrier animals there is a 25% chance that the offspring will be affected. Both AM and NH are serious defects that will result in the death of an affected calf. You can avoid any chance of the defects by using a bull that has been tested free ( AMF and NHF), or has no carrier ancestors in his pedigree. Of course, without a test there is always the risk that the pedigree is incorrect. The other two defects are less serious. CA, also called “Fawn Calf” will result in a calf that looks rather fawn like, with an arched back. Most outgrow it and look normal as an adult. DD is a simple recessive, but does not always express itself. You can have a calf that received the DD gene from both parents and it may still appear 100% normal. American Angus requires that any potential carriers of AM, NH or CA be tested free of the defect in order to be registered. The DD defect is very unlikely to be expressed, and therefore they do allow registration of potential DD carriers.

Arthrogryposis multiplex AM
What is Arthrogryposis Multiplex (AM)?
AM was recognized as a genetic conditionon September 16, 2008.
Calves are born dead or die shortly after birth. The spine and legs appear crooked or twisted and the joints of the legs are often fixed in position. Front legs are contracted and rear limbs may be contracted or extended. Calves are small and appear thin due to limited muscle development. There may be a cleft affecting the nose or palate.
http://www.angus.org/pub/AM/AMFactSheet.pdf

Neuropathic Hydrocephalus NH
What is Neuropathic Hydrocephalus (NH)?
NH was recognized as a genetic condition on June 12, 2009.
Calves that are carried are born near term and may have 25-35 pound birth weights. Some evidence also points toward possible early abortions due to the defect. The cranium is markedly enlarged (volleyball to basketball sized). The bones of the skull are malformed and appear as loosely organized bony plates that fall apart when the cavity is opened. The cranial cavity is filled with fluid and no recognizable brain tissue is evident. The spinal canal is also dilated and no observable spinal tissue is found.
http://www.angus.org/pub/NH/NHFactSheet.pdf

Contractual Arachnodactyly CA
What is Contractural Arachnodactyly (CA)?
CA calves are normally born alive and most can walk, suckle and survive. The birth weight of CA calves is normal. The phenotype is subtle and hence CA may not initially be recognized as an inherited defect. Contractures which reduce the range of angular movement of the upper limb joints are present at birth in CA but are much less severe, without rigid joint contractures. Due to these contractures, CA calves at birth assume an abnormal crouched posture, resembling an elk or deer fawn, with the feet placed more to the rear that normal, hocks pulled up and back and the spine slightly arched. In their first days of life, CA calves are also flat down on their pasterns. Although there is a reduced range of movement ("contracture") in the upper limb joints, particularly the hip, stifle and hock, there is an increased extensibility of the lower limb joints, particularly the pasterns. CA affected calves are reported as taller and more slender, than their unaffected siblings.
http://www.angus.org/pub/CA/CAFactSheet.pdf

Developmental Duplication DD
What is Developmental Duplication (DD)?
DD is an abnormality that has been long-observed in Angus cattle, but was previously thought to be caused by conjoined twins or other anomalies during fetal development. This abnormality was recently found to be a simply inherited recessive genetic condition passed through certain lines of Angus cattle. Animals affected with this condition can sometimes be born with an extra limb or part of an extra limb (a condition referred to as polymelia)

 

[boondocks]

Below are descriptions of the most common defects identified in Angus cattle. Some or all of them may also be present in other breeds of cattle. Carriers of these defects can be identified with a blood test. They are simple recessives, and the calf must receive the gene from both parents in order to be expressed. When you breed two carrier animals there is a 25% chance that the offspring will be affected. Both AM and NH are serious defects that will result in the death of an affected calf. You can avoid any chance of the defects by using a bull that has been tested free ( AMF and NHF), or has no carrier ancestors in his pedigree. Of course, without a test there is always the risk that the pedigree is incorrect. The other two defects are less serious. CA, also called “Fawn Calf” will result in a calf that looks rather fawn like, with an arched back. Most outgrow it and look normal as an adult. DD is a simple recessive, but does not always express itself. You can have a calf that received the DD gene from both parents and it may still appear 100% normal. American Angus requires that any potential carriers of AM, NH or CA be tested free of the defect in order to be registered. The DD defect is very unlikely to be expressed, and therefore they do allow registration of potential DD carriers.

[

True for bulls but not heifers I think. they've gotta be tested but per the fact sheets heifers are registrable regardless of test result. any offspring from them would need tested etc

 

[boondocks]

From the AAA fact sheet on NH:


What is the AAA registration policy regarding NH?
If a calf is a potential carrier
submitted for registration after 9-13-12:

Heifers
Must be tested and can be registered regardless of the test outcome.
Bulls
Must be tested and only those that test NHF can be registered.
E.T. Calves
Registration is based on sex of calf and if they are sired by a bull that is an
A.I. sire as described below.
Steers
No test required.
A.I. Sires that are
confirmed carriers
Calves cannot be registered that are conceived more than 60 days after the date a non
-
owned bull (a bull
that would require an A.I. Service
Certificate) is listed as a carrier animal (NHC).
Definitions
NHC
-
NH Carrier, has been tested and carries the NH mutation.
NHF
-
NH Free, has been tested and does not carry the NH mutation.
NHP
-
NH
Potential Carrier, animal
that trace
s
to one or
more confirmed tested carrier animals in its pedigree
that have no intervening ancestors that have been tested free of NH

 

[Katpau]

Thanks Boondocks. I did not realize carrier heifers could still be registered. I have always sold the ones that tested carrier as stocker calves. I am keeping my good old carrier cows and testing any daughters I would like to keep as replacements. Several of my most productive cows are carriers. They will stay until they come up open.