CVM Ranch is a hub for horse and cattle reproductive research

Dr. Dale Kelley and Dr. Giovana Catandi look at data.

CVM Ranch is a hub for horse and cattle reproductive research

Thursday, January 2, 2025

Media Contact: Taylor Bacon | Public Relations and Marketing Coordinator | 405-744-6728 | [email protected]

For years, the Oklahoma State University College of Veterinary Medicine has been at the forefront of advancements in theriogenology, the study of animal reproduction.

The CVM Ranch, a key component in hands-on learning, serves as both a teaching site and a research hub, where veterinarians and students investigate reproductive health, fertility and genetic advancements in cattle and horses.

OSU researchers are advancing important production techniques, such as artificial insemination and embryo transfer, and are working to improve livestock reproductive health.

"The CVM Ranch has a heavy clinical caseload of stallions and mares, allowing us to conduct robust retrospective clinical studies relevant to the equine breeding industry," said Dr. Giovana Catandi, assistant professor of theriogenology. "The ranch also has a decent-sized herd of teaching and research mares, allowing us to conduct more controlled and detailed investigations using research animals."

Catandi started at the CVM at the beginning of 2024 and quickly became immersed in the research taking place at the ranch. One of her first studies since beginning at OSU focused on comparing stallion sperm mixing techniques. Catandi and her team looked at how different methods of mixing sperm after cushion centrifugation, a routine technique used to concentrate stallion semen, affect the quality and lifespan of the sperm. Specifically, researchers compared using a pipette and a vortex to mix the sperm. The pipette process involves manually drawing up and releasing the sperm in a pipette and the vortex is a machine that spins the sample at high speeds.

Catandi said they decided to compare mixing techniques because vortex mixing is an easier and quicker mixing method compared to pipette mixing, but no studies had ever been made to compare the effects of these mixing methods on sperm quality on stallions or other species.

"Vortex mixing is more user-friendly, quicker and requires less disposable supplies. However, it does require a small investment in purchasing the vortex mixer," Catandi said. "Pipette mixing is preferred in practice because many people think vortex mixing may damage sperm cells, but pipetting may waste more sperm cells because small bits of the semen attach to the walls of the pipette."

The study tested different speeds and times for the vortex mixer and compared them with different pipetting methods to determine the effect of each technique on sperm quality, longevity and clumping. Sperm clumping is a common problem after centrifugation and reduces sperm quality because clumped sperm cannot swim properly and fertilize an oocyte. The study found that neither mixing method had a significant effect on important sperm quality. There were fewer clumps found in vortex-mixed samples, but neither method harmed sperm.

When deciding which technique to use, Catandi suggested a vortex mixer may be the preferred option for veterinarians and others who work with stallion semen collection and preservation.

"If they have access to a vortex, this may be a quicker and easier semen pellet mixing method that can be safely used, without worrying that it may damage sperm quality, and maybe optimizing sperm recovery after centrifugation," Catandi said.

"This research might not directly help improve sperm preservation techniques or success rates of AI, but it elucidates that vortex mixing is a safe option for sperm mixing after centrifugation as it has no detrimental effects on sperm quality of longevity."

Catandi said the next potential steps for research in this area would be to examine the effects of vortex mixing for sperm that will be frozen or evaluate its safety for mixing sperm from other species that also commonly use centrifugation in semen processing.

Catandi isn't the only theriogenologist performing exciting research at the CVM Ranch. Dr. Dale Kelley, assistant professor of theriogenology, is in the second year of a three-year study to develop new, safe and effective antimicrobial strategies to treat antimicrobial resistance. With funding and support from the Grayson Jockey Club Foundation, Kelley is using gallium nitrate to treat bacterial endometritis in mares.

Endometritis is inflammation in the uterine lining that occurs just after giving birth. Treatment typically involves intra-uterine antibiotics, but Kelley is exploring an alternative approach by using gallium as disruptor of bacterial iron-dependent processes.

Iron is important for most bacteria because it's needed for important processes like making DNA and protecting against stress. Gallium is a metal that is very similar to iron, and some bacteria can't tell the difference between them. Because gallium can't work the way iron does in the body, it ends up replacing iron in the bacteria's proteins, which causes these proteins to stop working. This disrupts the bacteria's ability to survive, essentially starving them and leading to their death.

Kelley first looked at gallium as a treatment option during his residency at Texas A&M University where his mentor was doing research using it as a treatment for Rhoddococcus equi. Kelley did a literature review and found there was other work to look at its use to treat various bacterial infections.

"Growing public awareness of antimicrobial resistances underscores the need to develop alternative therapies for the treatment of uterine infections," Kelley said. "Although antimicrobial resistance is often considered to be concerning in equine reproduction, there are few studies evaluating changes in antibiotic resistance in bacteria isolates from mares' uteri."

The study is broken into a three-part progressive process. In the initial phase, the goal was to confirm the effectiveness of gallium as an antimicrobial agent against several different types of bacteria. Pseudomonas aeruginosa and Klebsiella pneumoniea. A second study would measure the levels of gallium in the blood and the uterus after different doses are given to determine how much active gallium is needed to treat infections.

"At this point, we have determined minimum inhibitory concentrations (MIC) for E. coli, Psuedomonas aurogenosa, Klebsiella pneumonia and Strep. Equi," Kelley said. "The data looks promising as a treatment for Psuedomonas, the other bacteria had high MICs, suggesting it may not be as effective against them."

The final phase will look at experimentally infecting mares, treating and then breeding them to ensure mares can get pregnant. It will also focus on the safety of gallium as a uterine treatment.

"Since gallium nitrate was used as a chemotherapy agent in humans, it seems unlikely to have systemin issues," Kelley said. "We want to ensure that it does not negatively impact uterine health, causing fibrosis or adhesions."

After the last phase of this is complete, the next study would be a field trial where treatments are performed in real clinical cases.

The CVM Ranch remains an invaluable resource for veterinary researchers, practicing veterinarians and students pursuing either path of the profession. The ranch supports a wide range of studies to improve livestock reproductive health. With its extensive facilities and a dedicated team of theriogenologists, the ranch provides a unique environment that fosters both innovative research and hands-on learning, advancing the field of animal reproduction at every level of the profession.

Catandi emphasized the theriogenologists' different backgrounds and areas of expertise, noting that while each brings a unique perspective to the table, their shared passion for advancing animal reproduction creates a collaborative and supportive environment.

"The theriogenology team at the ranch is diverse and inspiring," Catandi said. "Having other theriogenology faculty interested in research allows us to be involved in more studies and contribute to each other's studies and ideas."

This collaborative environment, paired with the ranch's resources, fosters groundbreaking research and continuous advancements in reproduction, benefiting not only the veterinary field but also the broader agricultural and equine industries.

Photos By: Elizabeth Perdue

Story By: Taylor Bacon | Vet Cetera Magazine

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