Genetic testing for early diagnosis of BRD
Researchers have discovered specific genetic markers related to the immune response in cattle infected with viruses associated with bovine respiratory disease (BRD).
$2million in funding from the DAFM, DAERA and USDA is underpinning the research that Teagasc is undertaking in collaboration with the University of Missouri and the Agri-Food and Biosciences Institute (AFBI).
They are working on two projects that will determine how farmers treat BRD in the future, including:
- Genetic selection of animals;
- Early testing;
- Reducing antibiotic usage.
Their new research has identified how farmers could use this data to better select animals which are more resistant to infection.
Researchers detected the genetic markers in infected cattle’s blood cells, even when the disease was not apparent clinically.
Therefore, they say this raises the possibility of developing a diagnostic test, which could identify BRD in cattle before they become sick.
What is BRD?
According to the bodies, BRD is the main cause of cattle mortality from 1 month to 2 years of age.
The economic impact results from:
- High treatment costs;
- ‘Hidden’ costs such as weight loss, reduced reproductive performance, low milk yields or carcass blemish;
- The resultant impact on market price.
Mainly considered a seasonal problem reaching its peak in autumn and winter, it can also be a year-round problem dependent on climate.
According to the above, BRD results from a complex interaction of pathogens, predominately viral and bacterial agents.
The initial insult predominately is the result of viral infection, in particular:
- Bovine respiratory syncytial virus;
- Also, bovine herpes virus type 1;
- Bovine parainfluenza-3 virus;
- Bovine coronavirus;
- And/or bovine viral diarrhoea virus.
These viral infections predispose calves to secondary bacterial and further viral infections, which include:
- Bovine adenovirus-3 or 7;
- Mannheimia haemolytica;
- Histophilus somni;
- Pasteurella multocida;
- Mycoplasma bovis;
- Streptococcus pnuemoniae;
- Mycoplasma dispar.
As noted above, the outcome of the first project has highlighted:
- The possibility of breeding for higher resistance to BRD;
- The development of a diagnostic test for early detection of the disease;
- The development of improved vaccine designs.
The second project, which is still ongoing, examines how the respiratory microbiome (bacteria and viruses which you normally find in the animal’s respiratory tract) changes following initial BRD virus infections leading to secondary infections.
The statement highlights that respiratory diseases cause more deaths in young growing cattle than any other diseases.
All respiratory viruses are transmitted by close animal to animal contact through the air.
Once infected, the animal is more susceptible to secondary bacterial infections, which researchers stress, have the potential to “seriously impact” on animal health and the profitability of the farm.
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