Genetics for the Dairy Case

Dr Marj Faust Data Driven Genetics

Daily in the dairy sector we see evidence of the well-known saying that consumers vote with their wallets.  During the last few years, our industry has experienced significant market growth for premium products including specialty and artisan cheeses, organic dairy products, Greek-style and other specialty yogurts, premium ice creams, butter, and branded milks.  Such growth provides evidence that a sizable and expanding portion of U.S. consumers pay price premiums for products perceived as being more healthful, appealing, and enjoyable.  Trends in the dairy case are important because they can directly impact the bottom line of dairies.



Dairies seeking to capture a portion of the value created by premium dairy products will be echoing the question posed by a local dairy farm owner I met up with recently, “What can we do to produce raw material (milk) best suited for making products that consumers want and are willing to pay a premium for?”  Actions implemented by dairies can comprise management changes and genetics.  A few examples of management changes include nutritional changes to increase milk protein content, organic certification, and feeding changes to minimize milk fat depression.  Of course, on-farm management changes differ in their value proposition to individual dairies and some require having access to a premium-driven market channel.  In addition, many milk composition related factors are heavily impacted by genetics, and so should be part of the dairy’s genetic and bull selection equation.

Milk composition genetics must-haves

Fat, protein, and somatic cell score (SCS) will have been incorporated in the vast majority of bull selection criteria for operations across the U.S. and around the world.  These traits impact milk checks directly through dairy plant payment schemes and indirectly through lost milk production and treatment costs as is the case for high somatic cell score.  Volumes and percentages of milk fat and protein as well as somatic cell score have been shown to respond readily to genetic and genomic selection.  Beneficial response to selection can be seen even for traits such as somatic cell score which are easily influenced by management and the environment (see graphs below).

  During the past few years, payment and bonus schemes for milk have changed in response to the market situation and consumer demands.  By today, many markets have seen an erosion or even elimination of bonus schemes for milk quality.  High milk quality has become the market expectation.  On the other hand, a somewhat surprising and positive market development has been the strong and growing demand for milk fat.   Some experts attribute this growth in part to consumers seeking healthy fats.  The corresponding price trends for protein and milk fat are reflected in trends for the respective dairy products, cheddar and butter where the trend for butter has outpaced that for cheddar since the start of 2015 (see graph).

With declines in bonus payments for milk quality and year on year increases in the value of milk fat, it is important to ensure that the selection emphases today for SCS, and most importantly, fat and protein traits align with their respective impact on the dairy’s future economics.  Despite changes in bonus payment schedules, Somatic Cell Score should remain as a component of selection in concert with the new health trait, Mastitis to improve udder health.  For fat and protein, adjustments to the relative selection emphases may be required to best reflect future market demands.  For example, the timeline illustrates the increasing emphasis for Predicted Transmitting Ability of Fat (PTAF) as a component of the production traits portion of Lifetime Net Merit $ (see timeline graphic).

Milk composition genetics fine tuning and new opportunities

In addition to the more traditional milk composition related traits, today we have ready access to information on individual milk proteins through genomic testing.  Specific forms of individual milk proteins may have value for some markets.  Dairy products marketed by the A2 Milk Company are primes example of value creation based on an individual milk protein form.  Other milk components or specific milk protein variants or forms may influence the manufacturing properties of milk, and so may impact the value of milk for cheese making and other high value dairy products.  In fact, after extensive study in Italy a large commercial producer of Grana Padano, Parmigiano Reggiano, and other high value Italian cheeses restructured their milk sourcing and payment schemes to incentivize herds to provide milk that better meets their product-focused needs.

For casein and whey proteins, specific protein variants are determined strictly by genetics which means that they are not influenced by feeding or management.  Genomic tests are available for several of these today, and the animal’s genotype will be represented by the two alleles or gene forms identified in their DNA.

  • Beta lactoglobulin
    • A and B alleles can be distinguished
  • Kappa casein
    • A, B, and E alleles can be distinguished
    • Genotypes that may be identified: AA, AB, AE, BB, BE, EE
  • (A2) Beta casein
    • A1, A2, A3, B, C, and I alleles can be distinguished
    • Note that only females with two A2 alleles (A2A2) will produce milk that is 100% of the A2 beta casein form.

Essentially all commercially available sires for artificial insemination have genotype information available on these milk proteins.  For females, results can be obtained by genotyping animals through any of the commercially available genotyping services.

When breeding a herd that is well positioned for the future, what role should the milk protein genotype information play?  The answer to this question includes some obvious recommendations as well as a few unexpected ones.

Beta lactoglobulin – shows promise for human health

Beta lactoglobulin is a major whey protein and the subject of intensive research in the field of human nutrition and health.  Global dairy companies and universities are investing in work to expand our understanding of components in milk and dairy products (beyond calcium) and their impacts for human health and well-being.  Bioactive fragments resulting from digestion of beta lactoglobulin proteins have been found to play important beneficial roles for human health, including decreasing cholesterol levels and lowering blood pressure.  By early 2019 it is a bit premature to speculate about how best to incorporate beta lactoglobulin information into sire selection and breeding programs.  However, it is a good idea to keep checking back because we truly are cracking open the door of understanding on dairy products and their beneficial effects for human health.

Kappa casein – new developments require our focus

Kappa casein has been on the dairy genetics radar screen for many years after several university studies reported obtaining higher cheese yields from kappa casein BB versus AA milks.  However, beyond the research setting commercial cheese makers have been unable to identify clear and consistent product yield advantages for kappa casein BB milk when the overall protein contents of the AA and BB milks are equal.

Recently, research groups in Europe and subsequently in the U.S. have identified a new variant, kappa casein E.  Investigations on kappa casein E are underway, but some reports from the field suggest that milk containing the E form is less desirable for dairy products which require curdling the milk.

Due to the importance of casein proteins for cheese making, we can expect on-going research to shed more light on the importance and value of individual kappa casein forms including the A, B, and E variants.  Today, key goals for incorporating kappa casein information into sire selection and breeding programs are to avoid doubling up when an E-carrier sire is used, and generally to minimize the use of sires with the kappa casein E allele.  In addition, for most milk markets it is helpful to ensure that the herd contains 35% or more of the B variant allele.  Higher percentages can be economically beneficial for herds that are paid premiums for kappa casein BB milk.



Beta casein (e.g. A2) – market-specific approaches

For cheese making, research is uncovering that beta casein proteins may be essential for the hardening of curd.  However, today the public image of beta casein does not center on cheese, but instead centers on beta casein A2.  Remarkably, the promotion and marketing of milk containing only A2 forms of beta casein has raised the visibility and value around the world for these particular casein proteins.  For those who are interested in a scientific overview of purported health implications for beta casein A2-only containing milk, Gonca Pasin, Ph.D., executive director at the California Dairy Research Foundation provides an article on the Foundation’s website (

For dairies, the question is whether there is added value today and into the future for beta casein A2 genetics.  Not surprisingly as with many topics in our industry, different situations may require different approaches.  Specifically, herds which are positioned to capture value via beta casein A2 genetics are actively encouraged to pursue this market.

For cheesemaking, a handful of research groups have begun to evaluate whether beta casein variants have implications for the cheesemaking process and quality parameters of cheeses.  Reports from early studies suggest that beta casein A2 variants may not be preferred for the production of cheeses and other cultured dairy products.  Additional research studies will be helpful in determining whether there is a repeatable advantage for cheese and cultured dairy foods production when using beta casein A1 variant containing milks.  This means that for most dairies, there is no strong incentive to focus on beta casein A2 genetics.

Calcium, lactoferrin, distinct fatty acid profiles, and other milk constituents – future opportunities

Research is revealing that other constituents such as calcium, other mineral salts, fatty acids, vitamins, enzymes, and bioactive components such as lactoferrin also influence the processing and nutritional properties of milks.  As a consequence, dairy food companies are investing widely in developing dairy foods that enhance health benefits and functional foods aimed towards the new field of personalized nutrition.  For the more near term, companies and the public sector also are studying specific characteristics of milks that improve their processing characteristics and sensory parameters such as flavor, texture, and visual appeal of the products.  Genetics plays a significant role in many milk constituents including minerals, fatty acids, vitamins, enzymes, and other bioactive components such as lactoferrin.  New and beneficial findings can open a door of opportunity for our future to better tailor the milk and other dairy products we produce and sell to provide more health benefits and sensory appeal to consumers.

Editor’s note: Dr. Marj Faust is a founder and principal of Agri Innova LLC and Data Driven Genetics, where she and her team partner with established and emerging organizations as well as farming businesses globally to build strategy and deliver innovation. She was an R&D executive at ABS Global and Genus plc, served on the faculty at Iowa State University, provided consulting services in regulatory sciences to Novartis/Syngenta Seeds and FASS, and has held leadership posts in several dairy organizations. Readers may contact her with questions or suggestions at [email protected].

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