Genetic Defects in Beef Cattle

Uploaded by purduebeefteam on 23.07.2010

Genetic Defects in Beef Cattle Dr. Terry Stewart, PhD.
Department of Animal Sciences, Purdue University
Hi, I’m Terry Stewart with the Department of Animal Sciences at Purdue University. Here
we see several examples of dwarfism in cattle. The two pictures on the left are called bulldog
dwarfs. One happens to be in an Angus background, the other one is in a Hereford. The one picture
on the right is called a quadroplastic dwarf, it is a shortening of all 4 limbs. Dwarfism
occurs in all breeds of beef cattle. There are also several other types, you may have
heard of snorter dwarfs or needle nose dwarfs. Dwarfisms in general are controlled by a single
locus. It is usually a recessive trait, although there is evidence that there may be some pleiotrophy,
involving multiple loci. To date, there really aren’t any genetic testing systems for dwarfism.
Some breed associations have some further information so if you’re having questions
about dwarfism in your breed, I would encourage you to contact your breed association.
Here are a few examples of foot conditions that are associated with genetic defects.
On the left is a condition called syndactyly, sometimes goes by the name of mule foot. You’ll
see a normal cloven hoof on the bottom of the picture and
up on the top of the picture is an example of the syndactyly condition. It is an unsound
condition and the animal usually goes lame about the time that it reaches mature size.
On the right hand side is a different foot condition called polydactyly, or many toes,
it is controlled by a different series of genetics. The syndactyly is a single locus
trait with syndactyly being the recessive condition. Polydactyly, we think is controlled
by several different loci. We don’t have the specific genetic model of polydactyly
fully understood. If you suspect that you have syndactyly in your herd, there is a genetic
test available for it, contact your breed association, and they can help you