Management of genetic conditions
Meat & Livestock Australia May 10, 2024
Genetic conditions are caused by an abnormality in an individual’s DNA.
The incidence of a single genetic condition is normally rare in a population, but the existence of genetic conditions is common:
- Over 400 different genetic conditions have been identified in cattle.
- All breeds can experience genetic conditions
- Most genetic conditions do not have DNA tests available
- Some examples of genetic conditions found in beef breeds include Arthrogryposis Multiplex (AM), Idiopathic Epilepsy (IE), Developmental Duplication (DD) and Factor XI Deficiency (F11).
Genetic conditions are often associated with:
- Poor growth and fertility performance
- Structural unsoundness
- Varying levels of lethality
- Some are semi-lethal (not all affected individuals survive to maturity)
- Others are lethal (no affected individual survive to maturity)
The majority of genetic conditions seen in beef cattle are:
- Controlled by a single gene
- Have a simple recessive inheritance and are expressed in progeny who receive a copy of the recessive allele from both their sire and their dam.
- More likely to be expressed in populations with high levels of inbreeding.
Three possible genotypes:
- Free (zero copies of the genetic condition allele; does not have the genetic condition)
- Carrier (one copy of the genetic condition allele; does not have the genetic condition)
- Affected (two copies of the genetic condition allele; has the genetic condition)
Where available, DNA tests for genetic conditions can be used to manage and/or eliminate the genetic condition in a population.
The surest way to avoid the incidence of affected animals is to only use bulls that have been tested free of that genetic condition
- When the genetic condition status of both parents is known, other strategies to manage the prevalence of carriers and incidence of affected animals are available
Optional reading: Further information can be found in this Managing Genetic Conditions article.