Blood Collection at UA Beef Cattle Research Unit

Author: Grayson Robbins | Major: Animal Science with a Pre-Professional Concentration | Semester: Spring 2023
Grayson Robbins is a University of Arkansas graduate with a degree in Bachelor of Science in Agricultural, Food and Life Sciences. Her major is animal science with a pre-professional concentration within the Dale Bumpers College of AFLS. Her post-graduation plans include furthering her academic and career goals within the field of veterinary medicine. Grayson’s mentor, Dr. Lauren Rogers, is a DVM graduate of Oklahoma State University and now serves as a clinical assistant professor and veterinarian for the University of Arkansas’s Animal Science department. Their research project took place between the spring semester of 2022 and 2023, respectively, and concerns the disease Bovine Anaplasmosis in cattle.

Bovine Anaplasmosis is an infectious, hemolytic disease transmitted by the rickettsia parasite Anaplasma marginale in cattle. The beef cattle industry is the fifth largest agricultural commodity in Arkansas, so potential economic losses due to bovine anaplasmosis is a critical issue. In recent years, the University of Arkansas System Division of Agriculture and the Animal Science department have been interested in evaluating the prevalence and distribution of the disease within the state as well as in the university’s research herds. Beginning in 2019, a surveillance study was conducted across beef cattle herds located in the different regions of Arkansas to detect the presence of A. marginale. The results of this study indicated a possible 30% positivity rate within the Ozark Mountain region.

Due to the rising concern of infection and the lack of an FDA approved vaccine, herd management recommendations made to producers and implemented for the U of A’s herds have been adjusted to limit biological and mechanical transmission. Proper identification of the pathogen and corresponding treatment with tetracycline drugs, however, are dependent on accurate diagnostic methods. Previously tested beef cattle herds at the U of A’s Savoy and Batesville units tested seropositive in 2019 for A. marginale with low percent inhibitions; however, all seropositive animals tested negative for infection on DNA analysis. Current literature supports that A. marginale causes persistent infection in cattle. Therefore, following clearance of acute anaplasmosis, the pathogen typically remains in the animal’s bloodstream throughout its lifetime. As a result of the observed inconsistencies across diagnostic methods, further investigation of the U of A’s beef cattle herds involving their disease status was of interest to Dr. Lauren Rogers and other members of the animal science department. Dr. Rogers introduced me to the previous research regarding bovine anaplasmosis and we began our own blood collection and testing in May of 2022.

My undergraduate research project intended to utilize serological and DNA analysis methods to re-evaluate A. marginale prevalence among the previously seropositive animals still in inventory within the U of A research herds. The U of A beef cattle herds located at research facilities in Savoy and Batesville, AR were evaluated. Additionally, Dr. Rogers and I sought to evaluate the previously seropositive animals for co-infection with an Ehrlichia spp. The two rickettsia pathogens belong to the Anaplasmataeceae family, and this relationship is thought to contribute to antibody cross-reactivity. Cross-reactivity may lead to confounding results on serological tests, so differentiation should occur through DNA analysis. Historically, herd management recommendations have been based on serological testing; however, producers could potentially be making decisions on which cows to treat or cull based on false positive results.

Seropositive cows from these herds have no history of clinical illness and no specific antibiotic treatments for anaplasmosis are known to have been rendered. Anti-Anaplasma antibodies detected by cELISA analysis are only produced in response to A. marginale infections, which is known to cause persistent infection. As a result, animals presenting an antibody response to A. marginale are expected to carry the pathogen in their red blood cells. However, the qPCR testing conducted in the study did not detect A. marginale at any concentration in the blood samples from university owned cattle. Additionally, infection with an occurring Ehrlichia spp. was not observed, and the theory of antibody cross-reactivity was not significantly supported. Further investigation will be needed to assess the reliability of cELISA as a first-line diagnostic for producers and veterinarians. While cELISA is a cost-effective and practical screening tool for herds, qPCR testing is required to confirm the results of cELISA. The true prevalence of bovine anaplasmosis in Arkansas is still unknown and the sensitivity of diagnostics utilized to determine its presence across herds is vital for in-depth surveillance, which will be consequential to implementing effective control measures. As such, next steps in research should include reassessment of the U of A’s research herds in their entirety as well as evaluation of herds located in regions of the state with predicted high positivity for A.marginale infection.

In January of 2023, I presented an abstract for my research at the American Society of Animal Science Southern Section Meeting in Raleigh, North Carolina. At the conference, I attended research presentations with varying focuses in animal science. Academic professionals from many institutions participated in the meeting to learn about and discuss innovative ideas and research prospects for improving the performance of the industry. The abstract I presented was titled “Serial Evaluation of Anaplasma marginale Positivity Rate Within a Single Herd of Mature Beef Cows” in which our contributing authors sought to identify the presence of A. marginale in the U of A’s beef cattle herd at Savoy. By introducing our research to an audience dedicated to innovation and animal welfare, I was able to receive feedback that will motivate future directions for the project.

During the evaluation of infection in the university’s cattle herds, I have worked with livestock veterinarians, cattlemen, and lab technicians to trace the origins of contagions and analyze the immune response of a herd. To diagnose emerging diseases, identify the transmission vector, and productively treat an animal, investigation is required to identify a solution. Veterinarians make valuable contributions to the fields of therapeutics, public health, and agricultural development. My future career aspirations include obtaining a DVM and I am currently undergoing the application process for admission to colleges of veterinary medicine.

By graduation, I presented my research “Evaluation of Anaplasma marginale ELISA Positive Cattle for Co-Infection with Ehrlichia spp.” to my honors thesis committee comprised of members that assisted and supported the development and writing of the project: Dr. Lauren Rogers, Dr. Jeremy Powell and Dr. Brittni Littlejohn. The research experience has given me firsthand experience with beef cattle, connections with professionals and producers, and the opportunity to discuss the results with like-minded individuals. I plan to use this experience to continue to expand my knowledge of veterinary medicine and advocate for animal health.