Aggie Veterinarian Discovers Passion For Research, Studies Antibiotic Use In Food Animals

Ashlyn Holbert in a Texas A&M white coat
Dr. Ashlyn Holbert

As a doctoral student, Dr. Ashlyn Holbert ’22 is finding new ways to battle antimicrobial resistance (AMR), one of the greatest challenges in both veterinary and human healthcare worldwide.

Holbert developed a passion for veterinary medicine from young age, working on her Aggie family’s ranch in east Texas and through her exposure to a wide variety of animals in her father’s research laboratory. Throughout her undergraduate education, Holbert worked as a veterinary technician and was involved in mammalian genetics research, where she further kindled her love for both veterinary medicine and research.

To increase her chances of success of being accepted into a Doctor of Veterinary Medicine (DVM) program, Holbert decided to diversify her research experiences by conducting a summer research project with Drs. Keri Norman and H. Morgan Scott, associate professors in the Texas A&M College of Veterinary Medicine & Biomedical Sciences’ (VMBS) Departments of Veterinary Integrative Biosciences and Veterinary Pathobiology, respectively.

“I fell in love with the research environment and culture at the VMBS,” she said. “There’s just so much teamwork and support in our lab.”

Holbert decided to pursue becoming a veterinarian and applied to the DVM program at the VMBS in 2017. Unfortunately, her plans were delayed, and while she waited to be accepted into the DVM program, she was invited to pursue a doctoral degree in biomedical sciences (BIMS) under Norman. Holbert was accepted into the DVM program the following cycle and earned her DVM in 2022 while simultaneously working on her Ph.D. in antibiotic research.

Antibiotics are a popular focus for research in across the One Health continuum, which acknowledges the interconnectedness among human, veterinary, and environmental health.

“As a result of antibiotic usage, bacteria can evolve to become resistant to antibiotics,” Holbert explained. “Resistant bacteria can be very hard to kill due to the limited number of treatment options for patients. Our research group aims to discover novel ways to combat antimicrobial resistance in food producing animals to improve One Health.”

Holbert is also passionate about sharing new knowledge about AMR with others.

“That includes helping clients understand disease processes in their pets, teaching veterinary students how infections spread, and helping food animal producers and stakeholders understand the risks and benefits of using certain antibiotics in their herds,” she said.

When The Dust Settles

White cattle in a feedlot

While research on AMR is common, Holbert is pushing the boundaries by including microbial communities and environmental studies to complement her work. Her most recent research, published in the journal Frontiers in Microbiology, is a perfect example of how solving a complex problem like AMR takes a complex approach.

“In 2015, Texas Tech University published a research paper about the dangers of bacteria in the dust coming off cattle feed yards,” Holbert said. “It got a really big reaction, and a lot of people were concerned, especially in areas like the High Plains where the manure pack is very dry and there are high winds.”

Holbert’s research study utilizes environmental feedyard samples to further understand the bacterial dynamics within cattle and the feedyard environment.

“We used sequencing technologies to characterize the entire bacterial community, also known as the microbiome,” she said.

In addition to characterizing the microbiome within environmental samples, Holbert has also compared the bacterial communities among pens containing cattle that are treated with antibiotics and/or probiotics to see if they affect the bacteria levels in the environment.

“The project had multiple components because the issue we are facing is complex and multifactorial in nature,” Holbert said. “We wanted to get a sense of what kinds of bacteria were directly in the pen environment, but we also wanted to know whether drugs that affect bacteria — antibiotics and probiotics — could change the bacteria composition in the pen environment. We also wanted to know if it was possible for bacteria to linger in the environment and possibly continue to influence the environmental microbiome.

“What we discovered is that, within the span of 35 days, cattle appear to have more of an effect on the feedlot bacterial environment than it does on them,” she said. “There are other studies that look more closely at how bacteria from the environment are introduced into a cow’s system from lying down, licking each other, etc., but that cycle appears to take a longer time to develop.”

Paying It Forward

Pursuing two degrees at the same time was no easy task, but Holbert said it was made possible thanks to the mentorship she received from the VMBS’ research community.

“The mentorship I’ve received from Dr. Norman, Dr. Scott, and many others has helped me tremendously when it comes to gaining expertise in my field, having opportunities to present my work at conferences, and receiving guidance when writing grants and manuscripts,” she said.

In fact, one grant in particular has made a huge impact on Holbert and her career as both a DVM and Ph.D. student — the National Institutes of Health’s (NIH) Ruth L. Kirschstein Institutional National Research Service Award, otherwise known as the T32 grant, which supports graduates in fields like veterinary medicine who are also working on a Ph.D.

“Dr. Norman was the one who encouraged me to apply,” Holbert said. “It was challenging to write an NIH grant during my clinical rotation year of veterinary school, but thanks to her support, I did it and was accepted into this competitive trainee program. As a result, I have additional support and opportunities as an NIH trainee that have made a huge difference in my career.”

One opportunity Holbert was able to pursue thanks in part to T32 funding was the 4th AMR Course: A One Health Challenge in France, where experts across governmental agencies, academia, and industry worked with participants to create and implement strategies to target and reduce AMR in low-to-middle income countries, which face additional challenges in terms of regulation and judicious antibiotic usage.

“Although my focus has shifted to research, I still have a passion for veterinary medicine and making medical knowledge more accessible to the public so that everyone can understand the importance of prudent antimicrobial usage,” she said. “It’s important to provide reliable sources of information to the public instead of the things they find on social media or other misinformation. As I continue my research endeavors, I intend to find ways to share what I know.”

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For more information about the Texas A&M College of Veterinary Medicine & Biomedical Sciences, please visit our website at vetmed.tamu.edu or join us on FacebookInstagram, and Twitter.

Contact Information: Jennifer Gauntt, Director of VMBS Communications, Texas A&M College of Veterinary Medicine & Biomedical Sciences, jgauntt@cvm.tamu.edu, 979-862-4216


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