December 01, 2025

Epi. 262 – A Pilot Study Investigating Consumption Patterns of Chlortetracycline-Medicated Mineral Supplement Offered Free-Choice to Beef Cows on Pasture

30 minutes

AABP Executive Director Dr. Fred Gingrich is joined by Dr. Isaac Jumper, assistant professor and ambulatory clinician at Mississippi State University College of Veterinary Medicine. Jumper was the first author on a paper published in the Bovine Practitioner online first edition. This peer-reviewed journal published by AABP is open access. The target audience for the journal is the practicing cattle veterinarian and there are no publication fees for submissions. Find the journal at this link.

The objective of this paper was to study the temporal consumption patterns of chlortetracycline (CTC)-medicated mineral supplement offered free choice to beef cows on pasture and test the effect of cow age on CTC-medicated mineral supplement intake. The study involved an adaptation period to acclimate cows to the SmartFeed units and a trial period to test the study objectives. During the 27-day adaptation period, 76% of cattle consumed any amount of the diet during the day and the average total intake was just under 8 kg per cow or 0.3 kg per day. During the 46-day trial period, 27% of cows across all pasture groups consumed any amount of CTC-medicated mineral with an average amount consumed of just under 41 grams per day. The average dose of CTC consumed was 0.53 mg/kg per day which is less than the labeled dose of 1.1 mg/kg. The authors identified variability between cows in consumption of CTC-medicated mineral. The mean number of consumption days was 12.5, the number of consecutive days the average cow visited the feeder was 1.6 and the average number of days between visits was 6 days.

We discuss the implications for control of anaplasmosis with these results. The authors identified that in this study, feeding CTC-medicated mineral did not ensure that cows on free-choice pasture-based feeding programs did not consume the label dose of CTC. As the age of the cow increased, the frequency of visits decreased, and the total consumption of CTC-medicated mineral declined.

Veterinarians who are utilizing CTC for control of anaplasmosis should be familiar with FDA regulations on the Veterinary Feed Directive, including dosing, the difference between hand-fed labels and free-choice administration, and the prohibition of extralabel drug use for medically important antimicrobials administered in feed.

A pilot study investigating consumption patterns of chlortetracycline-medicated mineral supplement offered free choice to beef cows on pasture. (2025). The Bovine Practitioner, 60(1):1-11. https://doi.org/10.21423/bpj20269277

Questions and Answers: FDA Approved Free-Choice Feeding Options for Anaplasmosis Control in Cattle | FDA

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