Working to better understand pathogens associated with bovine respiratory disease; combatting Streptococcus suis without antibiotics or vaccination.

April 3, 2024

5 Min Read
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By Lori Tyler Gula, USDA NIFA

In 2006, the United States, Republic of Ireland and Northern Ireland launched a research and development partnership to accelerate economic development and cooperation across borders by encouraging trilateral research collaboration. In 2015, the USDA, Republic of Ireland Department of Agriculture, Food and the Marine and the Northern Ireland Department of Agriculture, Environment and Rural Affairs added agriculture as a partnership priority area.  

With funding from USDA’s National Institute of Food and Agriculture, researchers from the United States, Republic of Ireland and Northern Ireland are working to solve critical agricultural issues of concern to all three countries as part of this trilateral research collaboration.  

Understanding bovine respiratory disease 

Bovine respiratory disease is the most prominent disease in the cattle industry. In both the United States and Ireland, respiratory disease is the most common cause of mortality in cattle. In the U.S., more than 50% of feedlot deaths are attributable to BRD. Approximately 45% and 32% of deaths are attributable to BRD in calves aged 1 to 5 months old in Northern Ireland and Republic of Ireland, respectively. Estimated economic loss due to BRD is over $1 billion USD and up to £772 per animal in Ireland annually when considering the costs of prevention and treatment. 

As a result, researchers with the USDA Agricultural Research Service U.S. Meat Animal Research Center, North Carolina State University, Teagasc in Ireland and the Agri-Food and Biosciences Institute in Northern Ireland aim to reduce BRD associated costs, increase understanding of the disease complex and improve animal welfare. Specifically, they are working to better understand cattle respiratory pathogens, including bacterial and viral pathogens associated with BRD in U.S. beef herds and in Irish dairy calf-to-beef rearing herds and suckler calf-to-beef herds.  

“An understanding of the interaction of the bacterial and viral pathogens in the upper respiratory tract may help us to understand the impact of these pathogens on incidence and development of BRD in cattle,” said Tara McDaneld, a research geneticist at ARS. “This will enable study of the role of respiratory pathogen variation in respiratory disease incidence, which will provide a clearer picture of the relationships of profiles in animals that develop BRD or not and may lead to specific recommendations for treatment or vaccination.” 

To date, for the U.S. herd, ARS researchers have been able to evaluate changes in the bacterial and viral populations of the upper respiratory tract across multiple timepoints prior to weaning in addition to when the calves were diagnosed with BRD in the feedlot. This research also allowed them to identify common and novel bacterial and viral pathogens in U.S. and Irish cattle populations. 

“This information will aid in the diagnostic quest and influence the management of animals to reduce both the pathogen source and pathogen transmission,” McDaneld said. “Furthermore, we envisage that our data will be combined and integrated into international datasets and contribute to the global effort to understand the pathogens associated with BRD and utilize this information to generate diagnostics for early BRD detection and improved vaccine development.” 

Improving pig health 

The United States plays a significant role in global pork production. However, the opportunistic pathogen Streptococcus suis is a major concern in hog farming as pigs infected with S. suis have decreased growth rates. While antibiotics are commonly used to treat S. suis, broad application of antibiotics raises concerns because of the development of antibiotic resistant bacteria. Therefore, new treatment strategies to eradicate S. suis independent of antibiotics are needed.  

With funding from USDA NIFA, DAFM in Ireland and DAERA in Northern Ireland, researchers at the University of Wisconsin, Teagasc, University College Cork and Queen’s University Belfast have developed a health promoting bacteria to release antimicrobials to combat S. suis. Specifically, they engineered the probiotic Limosilactobacillus reuteri, or L. reuteri, to release proteins that are normally produced by bacterial viruses. These proteins are called ‘lysins’ can ‘lyse’ destroybacteria. L. reuteri contains these antimicrobials inside the cell. If L. reuteri passes through the GI tract, antimicrobials are released from the probiotic. 

“Success in this endeavor promises a breakthrough in combating S. suis  independently of antibiotic or vaccination treatments,” said J.P. van Pijkeren, principal investigator at the University of Wisconsin. “Our research is significant not only for its potential to reduce reliance on antibiotics in agriculture and reduce the selection for antibiotic-resistant bacteria but also for its broader implications for animal welfare, farm sustainability and even human health.” 

The research’s economic impact will be significant for the U.S. pork industry. With gross cash receipts from hog marketing reaching $28.02 billion USD in 2021, the industry supports a wide range of economic activities beyond direct sales. An estimated 613,823 jobs are involved in various stages of the pork value chain. This translates to approximately $35.86 billion USD in personal income and $57.20 billion USD in gross national product supported by the U.S. pork industry.  

According to Teagasc, the Irish pork and pig meat industry is the third most important agricultural sector in Ireland, ranking third in Gross Agricultural Output after beef and dairy and employing an estimated 8,300 people. It contributes nearly €1.5 billion to Ireland’s economy.  

“By addressing challenges such as Streptococcus suis-associated diseases in pig populations, this research contributes to the industry's sustainability and resilience. By safeguarding pig health and productivity, the research helps maintain stable production levels, which in turn sustains jobs and economic activity throughout the pork value chain,” van Pijkeren said.  

“Furthermore, by reducing reliance on antimicrobials and mitigating the risk of antimicrobial resistance, the research safeguards the long-term viability of the industry and helps protect against potential economic disruptions caused by antimicrobial-resistant pathogens,” he said.  

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