As a livestock farmer or breeder, you know the importance of maintaining the health and productivity of your animals. However, genetic diseases can often pose a significant threat to the health and well-being of your livestock, leading to decreased productivity, increased healthcare costs, and financial losses.
In this blog, we will discuss the impact of genetic diseases on livestock, provide examples of some common hereditary diseases, and explain how genotyping can help prevent and manage these diseases. By understanding the role of genotyping in minimising the risk of passing on genetic diseases, you can make informed breeding decisions and ensure your livestock operation’s long-term health and profitability.
Understanding the impact of genetic diseases
Genetic diseases are disorders caused by abnormalities in an individual’s DNA, the genetic material that carries instructions for organisms’ development, functioning, and reproduction. These abnormalities can range from single gene mutations to more extensive chromosomal abnormalities. Genetic diseases can affect various aspects of an individual’s health, including physical development, metabolism, and susceptibility to certain conditions.
The two main classes of genetic disorders are:
- Single-gene disorders: These disorders are caused by mutations in a single gene. They can be inherited in different patterns, including autosomal dominant (where only one copy of the mutated gene is needed for the disorder to be expressed), autosomal recessive (where two copies of the mutated gene are needed), or X-linked (where the gene responsible for the disorder is located on the X chromosome). Some disorders in cattle include arachnomelia, syndactylism, osteopetrosis, dwarfism, crooked tail syndrome, muscular hyperplasia, glycogen storage disease, and protoporphyria.
- Chromosomal disorders: These disorders result from abnormalities in the structure or number of chromosomes or translocations of part of a chromosome. In Bovine, for example, the 1/29 translocation has been identified in the Simmental, Charolais and Blonde D’Aquitaine breeds. Translocations affect fertility but no other production traits. Carriers of translocations have reduced conception rates and increased abortion rates.
There are several ways that genetic diseases can affect livestock health, productivity and profitability.
- Reduced productivity: Genetic diseases in livestock can lead to decreased growth rates, lower reproductive efficiency, and poor quality products such as meat, milk, or wool.
- Increased healthcare costs: Treating animals affected by genetic diseases can incur significant expenses due to veterinary care, medications, and specialised management practices.
- Morbidity and mortality losses: Genetic diseases may result in higher morbidity rates (sickness) and mortality (death) among affected animals, leading to financial losses for farmers or breeders.
- Reduced market value: Animals with known genetic diseases may have reduced market value due to concerns about their health, productivity, and the heritability of genetic defects to offspring.
Genetic diseases in livestock
Ovine Hereditary Chondrodysplasia (OHC) is a genetic disorder in certain sheep breeds, primarily observed in black-faced sheep. Chondrodysplasia is a single-gene disorder in a gene known to regulate bone growth and is characterised by abnormal development of cartilage and bones, leading to skeletal abnormalities. This disorder typically manifests in affected lambs as shortened limbs and a compressed body, resulting in a distinctive dwarf-like appearance.
Pompe disease is inherited in an autosomal recessive pattern, meaning an individual must inherit two copies of the mutated gene (one from each parent) to develop the disorder. Individuals who inherit only one copy of the mutated gene are carriers and typically do not show disease symptoms. In individuals with Pompe disease, the deficiency of the GAA enzyme results in glycogen accumulation within cells, particularly in muscles, including the heart and skeletal muscles. This buildup impairs muscle function and leads to the signs and symptoms associated with Pompe disease, which can vary widely in severity. Common symptoms may include muscle weakness, respiratory difficulties, heart problems, and infant developmental delays.
Both of these diseases can be tested through our DNA analysis services at XytoVet.
The crucial role of genotyping in managing and preventing genetic diseases
DNA analysis can help to significantly minimise the risk of passing on genetic diseases.
Identification of carriers and affected animals within a breeding population
Affected animals carry two copies of the mutated gene associated with the disorder and are likely to exhibit clinical symptoms. Carriers, on the other hand, possess one copy of the mutated gene and one normal copy, typically not showing symptoms but capable of passing the mutated gene to their offspring. Normal animals have two normal copies of the gene and do not carry the genetic disorder.
As discussed in the previous blog SNPs (What Are SNPs: Understanding Trait Identification and Selection), genetics disorders can, in some instances, be detected from genotyping data or require specific tests such as Polyermase Chain Reaction (PCR). Once the disorder has been identified and genetically studied, the results can be used to identify affected animals, carriers, and normal animals within the breeding population.
Better breeding and bloodstock selection
Breeding strategies are crucial in the prevention of hereditary diseases within a breeding population. Selective breeding is a primary approach breeders use once carriers and affected animals are identified. This strategy aims to decrease the frequency of the mutated gene associated with the disorder. Breeding pairs are carefully selected, with carriers mated to normal animals to produce offspring without the disorder. By controlling which animals are bred together, breeders can gradually reduce the prevalence of the genetic disorder while maintaining desirable traits within the population.
Additionally, avoiding high-risk matings is another important aspect of breeding management. Breeding decisions are guided by the genetic status of individual animals, ensuring that matings are not likely to produce affected offspring. This proactive approach minimises the risk of passing on the genetic disorder to future generations. By prioritising the selection of breeding pairs based on their genetic profiles, breeders can work towards establishing healthier and genetically diverse populations over time. These breeding strategies contribute to the overall welfare and sustainability of the breeding population while addressing the challenges posed by inherited genetic disorders.
Monitoring and management of genetic disease prevalence over time
As the breeding program progresses, ongoing monitoring and reassessment of the genetic status of animals within the population are essential. This allows breeders to track changes in allele frequencies, evaluate the effectiveness of breeding strategies, and adjust their approach as needed to further reduce the disorder’s prevalence.
XytoVet DNA analysis for the prevention of hereditary diseases
Genotyping plays a pivotal role in preventing and managing genetic diseases within breeding populations. Its importance lies in providing breeders with valuable genetic information that enables them to make informed decisions to mitigate the risks associated with inherited disorders. With early detection and selective breeding, genetic disorders can be avoided, which will help provide long-term health and welfare.
Discover how our genotyping services can improve your herd or flock, and get started with XytoVet. In some cases, these genetic conditions are included in the price of your test. Ask us today.
