How to Improve Livestock Health, and Cut Greenhouse Gas Emissions

Nearly 1 million dairy and beef cattle and calves in the United States die prematurely every year from contagious, preventable diseases. This not only costs livestock producers more than $854 million in lost revenue per year but it also means that more animals must be raised than necessary. Better control of diseases would improve productivity, enabling farmers and ranchers to produce more dairy and beef with fewer animals and therefore a smaller environmental and carbon footprint.

Gene editing, genetic engineering, and other new genomic and breeding technologies provide a promising approach to improve animal health and significantly reduce livestock emissions. In a new Breakthrough Institute analysis, we show how using biotechnology to control infectious diseases could reduce the carbon footprint of beef and dairy production in the United States (Figure 1).

How Genetic Engineering Controls Infectious Diseases

The agricultural sector is continuously challenged by infectious diseases, which not only compromise animal health and welfare but also impose heavy economic burdens and require producers to raise more animals and use more resources than they otherwise would. Selective breeding, although effective to some extent, has failed to control several major diseases and is often unable to keep pace with the rapid emergence and evolution of diseases like African swine fever and Highly pathogenic avian influenza. Genetic engineering and recently developed gene-editing techniques, like CRISPR, provide a more rapid, agile, and targeted approach. They enable precise alterations in the genetic makeup of animals, endowing them with traits that can resist specific diseases.

Take bovine respiratory disease (BRD), for example, a major concern for the beef industry. This pneumonia-like illness affects 16.5% to 21% of beef cattle in U.S. feedlots. Despite widespread vaccination — with respiratory vaccines administered to about 90% of feedlot cattle — BRD remains responsible for approximately 45%–55% of all feedlot deaths and significantly reduces animals’ rate of growth. To better control the diseases, researchers have used gene editing in experiments to alter the protein targeted by the main pathogen that causes BRD, Mannheimia (Pasteurella) haemolytica. The results showed that the altered protein was absolutely resistant to M. haemolytica’s mechanism of destruction.

Much like BRD, bovine viral diarrhea virus (BVDV) is devastating to cattle worldwide, and preventing BVDV in the herd can subsequently reduce BRD rates. BVDV can cross the placenta and infect developing calves, resulting in abortion, congenital defects, and calves that continuously shed the virus. Approximately 80% of cows infected with BVDV early in pregnancy abort their calves and 50% of persistently infected calves die. U.S. researchers have edited the protein that BVDV binds to in the host. The result was a gene-edited calf – named Ginger – showing dramatically reduced susceptibility to infection.

Gene editing and genetic engineering can reduce disease in the dairy industry as well. Mastitis, an inflammation of the mammary tissue, remains the most widely treated disease in dairy cows. Environmental pathogens have risen as major causes of mastitis, but contagious pathogens like the bacteria Staphylococcus aureus are still the most prevailing gram-positive bacteria associated with mastitis, globally. Yet, using available antimicrobials approved for lactating dairy cows, the expected cure rate of S. aureus mastitis is only about 20% and cows never return to normal milk production during lactation; the current recommendation is to remove cows with S. aureus mastitis from the herd. New approaches using modern biotechnology hold tremendous promise to better manage the disease – helping cows stay healthier and avoid being culled (i.e. removed from the herd). For example, researchers developed transgenic cows secreting lysostaphin – a bacteria-derived antimicrobial peptide. These transgenic cows showed no signs of infection compared to non-transgenic cows after exposure to S. aureus.

Livestock Health for Planetary Health

Using biotechnology to enhance animal health and welfare has tremendous potential to improve productivity and therefore reduce greenhouse gas (GHG) emissions and other environmental impacts. Bob Rowland, Ph.D. – one of the leading U.S. experts researching gene-editing for disease resistance – put it like this: “controlling infectious disease [through biotechnology] is the next frontier in livestock sustainability.” A 2023 global analysis showed that reducing global livestock disease levels by 10 percentage points in a given year could lead to an 800 million metric ton (MMT) decrease in GHG emissions, measured in carbon dioxide-equivalent (CO2e). Improved animal health can reduce emissions in the United States as well.

We modeled how increased cattle resistance to BRD, mastitis, and bovine viral diarrhea virus (BVDV) could reduce greenhouse gas emissions. We focused on these diseases because resistance to M. haemolytica, S. aureus, and BVDV through genetic engineering and gene editing has been demonstrated and because they are extremely destructive to the industry.

If half of the U.S. beef herd were resistant to BRD, about 309,000 fewer cattle would be needed to produce today’s level of beef, reducing emissions by 2.3 MMT CO2e per year (Figure 1). Similarly, if 50% of U.S. beef cattle were resistant to BVDV, current production could be maintained with about 149,000 fewer cattle, reducing beef’s carbon footprint by 1.1 MMT CO2e. Mastitis reduces dairy cows’ productivity in two key ways: their milk must be discarded while they have clinical signs of disease and when being treated with antibiotics and they produce less milk even after they have been treated and have recovered. Under a scenario where half of U.S. dairy cows were resistant to mastitis, it could reduce dairy’s carbon footprint by 1.17 MMT CO2e.

Is Genetically Engineered Livestock Safe to Eat?

The Food and Drug Administration (FDA) and many other regulatory and scientific bodies worldwide have concluded that genetic engineering – including gene editing and genetic modification (GMO) – does not inherently pose any new or unique risks. In addition, the many mechanisms for monitoring the safety of food after it enters the market apply both to genetically engineered and conventionally bred organisms. Still, U.S. federal agencies apply premarket regulation to products of biotechnology that they do not apply to products of conventional breeding; these federal biotechnology regulations under the U.S. Department of Agriculture (USDA), the FDA, and the Environmental Protection Agency evaluate products of genetic engineering before they enter the market for risks to humans, animals, and the environment.

The FDA, which is generally responsible for regulating genetically engineered livestock, has largely operated under an abundance of precaution, moving slower than many scientists and industry think necessary. To the FDA's credit, they are aware of the regulatory burden being placed on emerging technologies and have increased the speed and number of biotech approvals. The FDA’s first approval of a genetically modified animal for food use was the AquAdvantage salmon, which the agency took more than a decade to review. Recently, however, the FDA has shown the ability to be more flexible and expeditious by using enforcement discretion to approve gene-edited cattle more adaptable to the extreme heat brought on by climate change – emphasizing that the intentional genomic alteration in these cattle does not raise any safety concerns. In addition, the FDA conducted a full review and approved the GalSafe pig in significantly fewer years than the previous AquAdvantage salmon, determining meat from these pigs is safe for the general population to eat.

Recently, a two-year study was undertaken of gene-edited pigs developed by Washington State University researchers. It included an animal health assessment and verification that the animals were normal except for a single altered trait. This extensive research led to the FDA granting an investigational food use authorization, approving the meat from the animals for human consumption.

Policy Changes Needed to Scale and Commercialize Gene-Edited Livestock

While science has demonstrated that genetically engineered and gene-edited livestock have large potential benefits, they are far from being widely developed, adopted by farmers, or accepted by consumers. A number of policy changes are needed to realize their potential, including:

• Smarter regulations.
  As BTI has stated before, we should break free from the longstanding approach of regulation tied to the method of genetic engineering (i.e., process-based). Instead, regulations should be based on the trait of the resulting organism (i.e., product-based). In the absence of a shift to more product-based regulation, like Canada’s system, U.S. biotechnology regulations should expand exemptions from premarket regulation for low-risk gene-edited products, and premarket regulation should include tiered reviews — with an initial assessment of potential risk, and a second level of assessment if any risks are identified.
• More funding.
  USDA funds risk assessments of gene-edited and other biotechnology products through the Biotechnology Risk Assessment Research Grants Program. The program provides about $5.5 million in grants per year, with awards ranging from $25,000 to $650,000. Funding for these grants and staff for this program should scale up as biotechnologies like gene editing are increasingly used to develop healthy, disease-resistant livestock.
  

• Global alignment on regulations.
  The lack of regulatory harmonization across countries, combined with the high cost of regulatory approval, has prevented many genetically engineered crops from reaching the market. Livestock face the same risk. Producer adoption of animal health and productivity-enhancing technologies is contingent on continued access to global markets. If the U.S. gets gene-edited livestock regulations right but U.S. beef and dairy producers cannot export their meat and milk due to stricter regulations in the importing country, then the benefits of the technology will be greatly reduced.
  
  
  

Methodology:
We used current U.S. herd inventory and production data from the USDA National Agricultural Statistics Service to model business-as-usual morbidity (for example, slower rate of growth or reduced milk yield) and mortality impacts of BRD, mastitis, and BVDV. BRD was assumed to have impacted 21.2% of cattle placed on feed. BVDV was assumed to be present in 4% of beef herds. Mastitis incidence increased with parity from 12.5% in a cow's first lactation to 25.5% for three lactations or more. We assumed resistant cattle were otherwise healthy.

We calculated reductions in herd size that would maintain production levels based on how reducing or eliminating disease would increase meat and milk production per animal. The changes in beef and dairy herd sizes were used to calculate GHG reductions. An emission factor of 1.04 kg-CO2e per kg FPCM was used for the mastitis calculation. An estimate that beef production generates 213.3 MMT CO2e was used for the BRD and BVDV calculations.