There was a time when feeding milk replacers supplemented with antibiotics was considered a “blanket” insurance policy to protect calves from disease.

But that practice has changed considerably. Industry data suggests that 20 years ago, roughly 20-40% of all calf milk replacer contained antibiotics. Today, it’s less than 5%.

This evolution is based on a couple of converging factors. For one, the U.S. Food and Drug Administration (FDA), which regulates antibiotic use for both animals and humans, has changed regulations. The FDA has trimmed back the availability of “medically important” antibiotics – those labeled for both humans and animals – in food-animal production. This effort is motivated by the desire to minimize the risk of developing bacteria that are resistant to antibiotics, and maintain the potency of antibiotics for human medicine.

As a result, low-level, “sub-therapeutic” feeding of antibiotics is no longer allowed. All antibiotics in feed, including milk replacer, require a Veterinary Feed Directive (VFD) from the herd veterinarian prescribing the treatment. And antibiotics in milk replacer now are allowed to be fed only in short durations – typically 7-14 days – at higher levels to treat clinical disease.

Fortunately, at the same time, we’ve improved our calf-rearing practices to boost health and performance proactively, negating the need for “protective” antibiotics. This has been accomplished by focusing on timely delivery of high-quality colostrum; higher liquid-ration feeding rates and more nutrient-dense formulations; ventilation and housing conditions; and preventative vaccinations.

So, when are medications in milk replacers still appropriate? That’s a herd-specific decision that should be made on the advice of your veterinarian. But some common, beneficial uses include:

(1)   Cocciodiostats – Products like Bovatec® and Deccox® contain coccidiostats, which are not used in human medicine. They can be fed to all calves and work best as a preventative – rather than therapeutic – treatment. If you already have clinical coccidiosis in your calves, it is very challenging to treat it.

(2)   Therapeutic antibiotics – Neomycin is a long-used antibiotic that can be blended with milk replacer in a 1:1 combination with oxytetracycline (Terramycin) on order of a licensed veterinarian with a VFD. With a veterinarian’s prescription, it is also possible to feed neomycin alone, but only on-farm – not blended in milk replacer. Neomycin combined with oxytetracycline can also be added to milk replacer on-farm with a veterinarian’s prescription. But for more even distribution and precise dosing, it is advisable to have them blended into the milk replacer formulation at the plant. Oxytetracycline and chlortetracycline alone can be added on-farm. These antibiotic therapies usually are very effective in treating calves diagnosed with salmonella or E. coli. But again, they must be used only on the diagnosis, advice, and prescription of your veterinarian.

In addition to these medications, there are a whole host of other additives and supplements to promote healthy digestion and efficient calf performance. They include probiotics, mannan oligosaccharide (MOS), yeasts and yeast derivatives, colostrum-based supplements, plasma supplements and more. Some may be blended into milk replacer, while others are dosed separately. Each should be evaluated based on published, peer-reviewed data, and selected to fit the farm’s production goals set in cooperation with herd nutritionist, veterinarian, and other trusted advisors.

In another example of regulatory oversight, all food animal antibiotics were recently removed by the FDA from over-the-counter distribution chains. It is likely there will continue to be more – not less – regulation of antibiotics in food animal production in the future. Today, antibiotics still have an effective place in calf rearing. To help protect our ability to use them, it is up to all of us to deploy them responsibly, in a targeted fashion, and in conjunction with proactive management and non-antibiotic tools to keep calves healthy and thriving.

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