At Mississippi State University, ranked second in the nation for animal health by ScholarGPS, advancing animal health goes hand in hand with protecting valuable resources. In the College of Veterinary Medicine, Dr. Isaac Jumper, assistant professor and veterinary epidemiologist, leads research addressing one of the most persistent challenges for cattle producers in the Southeast, bovine anaplasmosis.
Caused by the bloodborne bacteria Anaplasma marginale, bovine anaplasmosis spreads through ticks, biting flies, and even routine handling of equipment, like shared needles. Infected cattle can suffer a rapid drop in red blood cells, leading to severe illness or even death. Many cows are naturally carriers of A. marginale, and this carrier status is thought to protect the animal from severe bovine anaplasmosis, as long as the animal’s immune system remains healthy. For decades, producers have relied on the antibiotic chlortetracycline, known as CTC, to help control bovine anaplasmosis. It’s often delivered through free-choice mineral supplements.
In recent years, Jumper and Dr. Kelsey Harvey, assistant professor and scientist at the Mississippi Agricultural and Forestry Experiment Station, or MAFES, Prairie Research Unit, sought to describe the consumption patterns of mineral-fed free-choice to beef cattle on pasture.
“Using free-choice mineral supplements to deliver medications such as CTC is convenient, but cows don’t all consume the same amount each day. Some eat very little, while others consume far more than they need,” Jumper said. “That variability matters. If animals receive too little, the antibiotic can’t do its job. If they consume too much, it can disrupt herd immunity and potentially contribute to antibiotic resistance.”
Recently, Drs. Jumper, Harvey, Peixin Fan, assistant professor in the department of Animal and Dairy Sciences at MSU, and Geraldine Magnin, of Kansas State University, received a USDA National Institute of Food and Agriculture grant to further study the impact of delivering CTC in mineral supplements to cattle on pasture. This project seeks to better understand how cattle consume medicated mineral supplements and its impact for disease control and antimicrobial stewardship. The team studies herds during the typical summer grazing season when flies and ticks are most active. The bacteria causing bovine anaplasmosis are most often transmitted within herds during this period.
The project focuses on three key questions: “How much CTC are cows actually consuming on pasture when fed free choice CTC-medicated mineral? Does increased consumption alter rumen bacteria or encourage the development of microbes resistant to antibiotics? And, could some cows inadvertently consume too much CTC, thus clearing their protective carrier status?”
Answering these questions will give Mississippi cattle producers better decision-making tools.
“We know some herds are endemically infected, while others are completely naïve,” Jumper said. “Not every herd needs antibiotics, and for those that do, we need to use them wisely.”
Antimicrobial stewardship is at the heart of the project; CTC is part of a drug class still important in human medicine, and the responsible use in livestock is critical for its long-term effectiveness. By understanding real-world consumption patterns, Jumper and his colleagues hope to recommend strategies that are practical for producers and protective of animal and public health.
“This grant represents years of groundwork and collaboration between the College of Veterinary Medicine and MAFES. We are grateful for the support from Dr. Harvey and the MAFES Prairie Unit to continue this important work,” Jumper said. “Ultimately, our end goal is simple: healthier herds, smarter antibiotic use, and stronger outcomes for Mississippi beef producers.”
