Dairy Cattle Genomics is Quietly Improving Sustainability

Corey Geiger

January 17, 2024

• With so much attention on sustainability in agriculture, dairy has a largely untold portion of that story: genomics.
• In the past 15 years, dairy farmers have been using genomic science to select cattle traits that improve productivity, which in turn supports sustainability. The U.S. dairy herd today is just 1% larger than in 2008 but produces 19.2% more pounds of milk and 32.2% more pounds of butterfat. 
• The dairy industry still has room to grow more efficient through genomics. The industry’s Net Merit index, which serves as a proxy for cattle genetic progress on sustainability, shows that a cow produced by combining the best-known genes would be three times more sustainable based on improved genetics than the top Holstein bull on the market today. 

As food producers, processors, marketers, distributors, and consumers look to effectively manage their environmental footprint and social impact, sustainability of the dairy industry is under examination. But dairy has a largely untold portion of that story: genomics.

Since the introduction of cryogenically frozen bull semen in the 1950s, dairy farmers have been using artificial insemination (A.I.) to improve the next generation of their dairy herds and farm safety by eliminating mature bulls from their farmsteads. During the next six decades, genetic improvement largely remained the same as identifying the succeeding generation of elite bulls required eight years of elaborate progeny testing.

That all changed in 2008 when genomics was introduced to the dairy industry. Genomics, the comparison of an individual animal’s DNA to the phenotypic performance of the entire population, reduced the generation interval with minimal loss in accuracy. Genomics has been the most important reason for improvements in milk, butterfat, and protein production, cow health, and cow longevity.  

A big leap forward

While several indices track genetic progress, the Net Merit Index (NM$) is the most universally implemented index across all major dairy breeds as it combines over 40 traits that consider production, health, longevity, feed efficiency metrics and confirmation into one measurement based on U.S. dollars. The economic values are steeped in research and a conservative $16.50 per hundredweight (cwt.) milk price is used for the production traits. The NM$ index is formulated by geneticists at USDA’s Animal Genomics and Improvement Laboratory (AGIL) and published by the Council on Dairy Cattle Breeding (CDCB).

Under the progeny test system, the average genetic gain from 2000 to 2004 was $13.50 per year for marketed Holstein bulls. That means that with each successive year, the new crop of bulls would sire daughters that were $13.50 more profitable for the combined set of 40 traits than the previous year. For various reasons, the gains from 2005 to 2009, prior to and right after the introduction of genomics, moved up slightly to $36.90 per year as calculated by CDCB research scientist George Wiggans.

By 2010, just two years after genomic testing became commercially viable in the United States, genetic improvement leapt forward, more than doubling from $36.90 per year from 2004 to 2009 to the $83.33 annual genetic gain from 2010 to 2022. That is a six-fold improvement compared to those years before genomics, $70 in additional value per cow per year.

For the U.S. dairy industry, that’s a $329 million annual net gain when extrapolating this $70 annual gain per female across the annual U.S. dairy heifer calf crop where roughly half the 9.4 million cows have a heifer calf each year.

This profound development greatly enhances sustainability. With each passing year, new Holstein bulls entering active A.I. service father offspring that generate $83.33 in combined gains that enhance sustainability related metrics. These metrics include more milk production, savings due to better health, improved longevity, better feed conversion, and other economically important traits. It’s a sustainability story because the resulting offspring produce more nutrition with less inputs. In documenting this story, Holsteins serve as a good bellwether for the analysis as 89% of all genomic tests run in the U.S. were in the Holstein breed. Overall, genomic testing platforms are available for five major dairy breeds with the Jersey breed accounting for an additional 10% of all tests.

It’s important to note that these genetic gains are cumulative as dairy farms routinely keep heifer calves from their cows for successive generations. With that in mind, the aggregate gain since 2010 would be $4.28 billion when calculating the full genomic impact.

From a sustainability standpoint, this means the U.S. dairy industry needs fewer dairy cows with each passing year to supply the same amount of milk to serve the domestic market. Alternatively, the U.S. dairy industry has transformed that new growth in milk, butterfat, and protein into dairy products to deliver nutrition to international customers. In both scenarios, modern cows make better use of resources and that reduces dairy’s carbon footprint and methane intensity for milk, butterfat and protein.

Genetics outshine solar energy

The genomic revolution itself is an impressive breakthrough. However, comparing a recent solar project at one of the world’s largest A.I. facilities fully brings the economic importance of genomics into clearer light.

ABS Global, and its parent company Genus, recently built a series of new bull barns in Wisconsin to house 480 of the world’s most elite A.I. bulls and installed onsite solar panels to produce electricity for the complex. Part of the complex includes a major lab to process bull semen via a laser sorting process to create sexed semen that now accounts for nearly half of all sales in the U.S. The resulting sexed semen product allows dairy farmers to use beef semen on dairy cows to reduce the number of replacements housed on farms, and to realize more immediate revenue from dairy-beef cross calves eventually harvested for beef.

On the sustainability front, research indicates that beef-dairy crossed calves are approaching the same efficiency as beef cattle and, in some cases even better. Also, beef-dairy crossed calves are 30% more efficient at converting feed to beef than Holstein steers, and are on feed fewer number of days according to research by Dale Woerner at Texas Tech University. This improvement in feed conversion and fewer days on feed prior to harvest yields a net carbon footprint reduction and reduced methane emissions.

Circling back to the solar panels mentioned earlier, ABS Global found the combined amount of carbon saved by the solar panels’ production of electricity for the facility over 10 years is less than the carbon savings from just one month of genetic progress from future offspring of the facility’s 480 bulls. 

ABS Global staff used data from Alliant Energy to determine the energy requirements for the facility over a 10-year span and then calculated carbon savings in metric tons from the solar panels. In calculating the genetic gain on offspring, the $83 annual gain in NM$ was divided by 12 months to net a $7 monthly gain. That monthly improvement was multiplied across the future offspring produced in a given month by ABS Global bulls. That genetic gain, and its sustainability story, is measured by more production, better health, and longer cow life via the Net Merit Index. Again, it’s about getting more from cows with less inputs. 

The impact for dairy processors

To verify genomic predictions with real world cow performance, Pennsylvania State University’s Chad Dechow plotted butterfat and protein production from Holstein cows in the pre-genomic and the genomic era. From 2000 to 2009, butterfat production improved annually by 0.46% moving from 932 to 976 pounds per head for Holstein cows born in each respective year. The annual gain for butter fat production leapt to 1.75% annually in the genomic era as actual butterfat production moved from 1,005 pounds to 1,216 pounds from 2010 to 2021.

The same pace of change played out for protein production. From 2000 to 2009, protein yields in U.S. Holstein cows moved from 763 to 807 pounds, a year-over-year improvement of 0.56%. Genomics more than doubled gains at a 1.23% annual gain as protein production moved from 821 pounds in 2010 to 942 pounds for cows born in 2021.

Bottom line: At the onset of genomics, the U.S. dairy herd had 9.3 million cows and has grown less than 1% some 14 years later. Yet the national dairy herd produces 19.2% more pounds of milk and 32.2% more pounds of butterfat than it did in 2008. Genetics has made a significant contribution as has better feeding and cow care.

The cow-side impact

While the sire impact has been tremendous, genomic testing is starting to make significant inroads as more females get tested each year. It took seven full years for the collective U.S. dairy industry to run 1 million genomic tests from 2008 to 2015 through CDCB. Then it took another 26 months to run the second set of 1 million tests by July 2017. 

It’s at this point that commercial dairy farms more fully bought into genomic science and started to test more heifer calves at birth to determine those animals that would make the best replacements by making the best use of resources. Those positive outcomes included less methane production, a reduced carbon footprint, and less feed for each additional unit of milk. 

Since 2020, it’s taken less than 12 months to accumulate an additional 1 million genomic tests. By August 2023, CDCB received its 8 millionth genomic test. Today a remarkable 93% of genomic tests are run on female dairy animals and estimates indicate that 20% to 25% of the U.S. dairy heifer calf population is being tested annually. This constant collection of new data makes the dairy cow the most studied domestic animal on the planet. 

The genetic super cow isn’t in sight

Could genetic improvement be reaching its ceiling? Not even close, based on January 2024 calculations by AGIL senior research geneticist Paul VanRaden. In taking the most elite haplotypes (genes) from all the 7 million Holsteins in the genomic database, the very best possible combination would yield an animal with $5,772 NM$. That lofty number is far away from the top Holstein bull now in the marketplace at $1,361 NM$. With those numbers in mind, the dairy community is only 24% of the way to breeding the perfect Holstein cow. That leaves an 324% or a three-fold topside for future genetic improvement.

This analysis only considers current evaluations. Genomic science can identify new traits that will help reduce methane production and carbon footprint, with the “feed saved” trait being the tip of the iceberg. To that end, CDCB is working with the Foundation for Food & Agriculture Research to collect data to further study methane and carbon. In addition, the Greener Cattle Initiative and its research consortium have awarded some $5 million to support research to mitigate enteric methane emissions. The ultimate goal is to collect comprehensive data to create a national genomic evaluation for methane emissions. When fueled by the power of genomics, this work will open the next chapter in breeding more sustainable cows.