Genetic testing is making significant strides in dairy farming. These advanced techniques offer farmers new ways to enhance herd productivity, improve animal health, and adopt sustainable practices.
To delve deeper into its nuances and practical applications, Food For Mzansi interviewed Dr Simon Lashmar, a leading animal breeding and genetics researcher at the Agricultural Research Council (ARC).
According to Lashmar, “Genetic testing is a method where we look at genetic changes, also referred to as mutations or variants, in the DNA of animals.
Some of these genetic mutations can either cause disease or lead to the expression of certain desirable or undesirable phenotypes.”
Understanding these genetic changes is crucial, as they are inherited from the parents, with animals receiving approximately 50% of their DNA from each parent.
Lashmar elaborated on the application of genetic testing, stating that the first step involves collecting a sample, which could be blood, tail hair, tissue, or milk in the case of dairy cattle. This sample is used to isolate DNA, and the genetic code is then read and captured from this isolated DNA.
“We can use this information for various applications downstream,” he noted.
Types of genetic testing
The types of available tests depend on the farmer’s purpose and can be broadly divided into three categories: phenotypic selection for consumer preference of desirable traits, DNA profiling and parentage testing for animal identification, and genetic selection for improved performance or production.
Lashmar highlights that “phenotypic selection usually targets single gene mutations, such as polled status in cattle, while genetic selection for improved production involves multiple genes with an additive or cumulative effect.”
When asked about the genetic markers associated with higher milk production, Lashmar mentioned two predominantly used DNA markers: microsatellites and single nucleotide polymorphisms (SNPs).
“Milk production is a polygenic or additive trait, controlled by many genes with a cumulative effect,” he emphasised.
Key genes influencing milk production include DGAT1 and 2 and prolactin genes, which have been found to influence milk yield. Additionally, genetic tests for milk protein genes like A2 beta-casein, kappa-casein, and beta-lactoglobulin are available, each contributing to different aspects of milk quality and yield.
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Benefits for dairy farmers
The practical benefits for dairy farmers stem from including these genetic markers in testing panels or using genomic selection to estimate an animal’s genetic merit.
“This can help farmers select superior animals and remove inferior ones, leading to improved herd productivity and profitability,” Lashmar explained.
For farmers looking to start using genetic testing, Lashmar recommends beginning with a detailed herd analysis to align goals with market conditions and identify appropriate genetic tests. “Focus on testing the most profitable animals, such as replacement heifers and bulls,” he advised.
While initial investments can be significant, the potential returns include accelerated genetic progress, cost savings from not raising excess replacement animals, and developing alternative revenue sources.
Regarding frequency, Lashmar noted that it depends on the purpose and application.
“Genetic testing can inform decisions on which cows to keep or cull initially and continue to assist in mating decisions to reduce the risk of inbreeding and recessive genetic conditions,” he says. Routine applications, like parentage testing, should be done every calving season.
All dairy breeds, including Ayrshire, Jersey, and Holstein, can benefit from genetic testing, especially young animals. “Testing at a young age provides reliable genomic information, allowing quicker decision-making,” Lashmar remarked.
Challenges and misconceptions
Despite the clear benefits, challenges in understanding and applying genetic test results remain. “There is often a limited understanding among farmers about how genetic tests work and how to apply the results,” Lashmar noted.
To overcome these challenges, he stressed the importance of informal education and awareness-raising efforts. Additionally, accurate pedigrees and performance recording are essential to complement genetic testing.
Common misconceptions also need addressing.
Lashmar clarified that genetic testing does not modify the DNA of animals but serves as a tool for monitoring, managing, and selecting better animals.
He highlighted the role of genetic testing in promoting sustainable and environmentally friendly dairy farming practices by improving resource utilisation and reducing environmental impacts.
Choosing an ideal provider
Selecting the right genetic testing service or provider involves considering several factors, including cost, accuracy, reliability, and after-sales service. “Accuracy and reliability are crucial, and turnaround times are important since animals are often sold based on genetic results,” Lashmar pointed out.
He also mentioned that some providers offer unique tests and are willing to develop tailor-made solutions for farmers.
Looking ahead, Lashmar sees genetic testing continuing to revolutionise dairy farming. By enhancing productivity, sustainability, and profitability, it holds the promise of a brighter future for dairy farmers.
“Genetic testing can significantly contribute to a farm’s sustainability by reducing greenhouse gas emissions and the need for frequent replacement,” he concluded.
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