Post by Nonesuch Melissa on Jun 30, 2014 17:24:53 GMT -5
I had someone ask me to explain chondro and PHA ... did I miss anything?
Sure. Chondro and PHA are both genetic recessives that have to be carried by both the parent bull and cow for the calf to be affected, although only one has to be positive for the mutation for a calf to be born a carrier. Right there is where the similarities end as they are vastly different problems.
Chrondroplasia is a form of dwarfism. In affected animals the cannon bones of the legs are shorter and the head/body ratio is skewed with the head being slightly larger than normal. While some of these animals look weird, many are attractive, with a more beefy looking type and some people purposefully breed them for this reason.
The problems are that chondro animals can suffer arthritis and heart defects, they have an overall shorter lifespan than their non carrier counterparts, and lastly if the gene is doubled the calf can be what is called a Bulldog calf. Almost always born dead or dying shortly after birth this calf will be severely deformed. Because they are misshapen they also sometimes (rarely) cause difficulty with delivery.
PHA (short for Pulmonary Anascara with Hypoplasia). It is different in that the gene casuse a condition that is not only incompatable with life (like bulldog calves) but a PHA calf can (often does) take on water and grow to a size that can not be delivered, sometimes also killing the cow or necessitating a Cesarean Section (removal of the calf by surgery). The other thing that makes PHA more problematic is that PHA shows no outward signs in the cattle that carry it, whereas most dwarf (chondro) cattle can be identified by their look.
Breeding a non-carrier X carrier gives 0% affected, 50% normals and 5o% carriers on average. Breeding two carriers together gives 50% normal, 25% carrier and 25% affected (bulldog ir waterbaby).
Our herd is PHA and Chondro free. I unknowingly bred a PHA cow for three years before the test was available and never had a PHA positive calf. There are very strong feelings on both sides of the PHA/Chondro issues and you will hear all kinds of things that may contradict what I've said here... Of course I personally also have a very strong preference for the red color because they do better in our hot climate but have been told by others that's pure bullcorn.... To each their own, I breed what I like and I'm not for telling anyone else what to breed.
As an aside. While there are a few people who breed Chondro purposefully they are harder to sell and sell cheaper and PHA positive animals are also hard to sell and sell MUCH cheaper since most Dexter owners believe they should be butchered. I am more for testing all bulls and not registering any positive bulls which means that while some animals would carry it none would die from it... but I don't run the show.
Hope that helps.
Sure. Chondro and PHA are both genetic recessives that have to be carried by both the parent bull and cow for the calf to be affected, although only one has to be positive for the mutation for a calf to be born a carrier. Right there is where the similarities end as they are vastly different problems.
Chrondroplasia is a form of dwarfism. In affected animals the cannon bones of the legs are shorter and the head/body ratio is skewed with the head being slightly larger than normal. While some of these animals look weird, many are attractive, with a more beefy looking type and some people purposefully breed them for this reason.
The problems are that chondro animals can suffer arthritis and heart defects, they have an overall shorter lifespan than their non carrier counterparts, and lastly if the gene is doubled the calf can be what is called a Bulldog calf. Almost always born dead or dying shortly after birth this calf will be severely deformed. Because they are misshapen they also sometimes (rarely) cause difficulty with delivery.
PHA (short for Pulmonary Anascara with Hypoplasia). It is different in that the gene casuse a condition that is not only incompatable with life (like bulldog calves) but a PHA calf can (often does) take on water and grow to a size that can not be delivered, sometimes also killing the cow or necessitating a Cesarean Section (removal of the calf by surgery). The other thing that makes PHA more problematic is that PHA shows no outward signs in the cattle that carry it, whereas most dwarf (chondro) cattle can be identified by their look.
Breeding a non-carrier X carrier gives 0% affected, 50% normals and 5o% carriers on average. Breeding two carriers together gives 50% normal, 25% carrier and 25% affected (bulldog ir waterbaby).
Our herd is PHA and Chondro free. I unknowingly bred a PHA cow for three years before the test was available and never had a PHA positive calf. There are very strong feelings on both sides of the PHA/Chondro issues and you will hear all kinds of things that may contradict what I've said here... Of course I personally also have a very strong preference for the red color because they do better in our hot climate but have been told by others that's pure bullcorn.... To each their own, I breed what I like and I'm not for telling anyone else what to breed.
As an aside. While there are a few people who breed Chondro purposefully they are harder to sell and sell cheaper and PHA positive animals are also hard to sell and sell MUCH cheaper since most Dexter owners believe they should be butchered. I am more for testing all bulls and not registering any positive bulls which means that while some animals would carry it none would die from it... but I don't run the show.
Hope that helps.
