Raising healthy, productive calves has been the primary goal of calf raisers since we started rearing calves away from their dams. But how we pursue that goal has evolved considerably. When calf milk replacer became commercially available decades ago, adding antibiotics like oxytetracycline, neomycin, and chlortetracycline was a common practice. Often these were delivered at “sub-therapeutic” levels, meaning they were not intended to treat disease, but rather to promote growth.

Recently, our approach to using antibiotics in food animals has changed significantly. As technology improved to detect antibiotic residues in animal tissues, regulators became concerned about antibiotics passing through the food chain. The creation of antibiotic-resistant bacteria that could cross over into human medicine also became a growing issue.

In 2017, the Veterinary Feed Directive (VFD) took effect in the United States. It required a veterinarian’s prescription for most antibiotics in feed, including milk replacer. The VFD also eliminated all sub-therapeutic use of antibiotics in animal feed.

Today, there still are a handful of medications that can legally be added to milk replacer, either blended in the bag, or as an add-pack. The advantage of blending at the manufacturing point is that animals receive a very consistent dose, and delivering the medication does not require an additional, on-farm step. On the other hand, add-packs provide versatility in that they can be incorporated into the liquid ration only when they are needed.

The medications currently approved for incorporation into milk replacer in the U.S. are:

• Antibiotics – The scope of antibiotic inclusion in milk replacer has narrowed to therapeutic use only, for a period of 5 to 14 days, depending on the drug. Currently approved antibiotics include oxytetracycline/neomycin; chlortetracycline; and oxytetracycline alone. All of them require a VFD, and each one has its own, specific dosage and withdrawal times. These drugs can be extremely helpful in treating pneumonia and some types of scours. The Bovine Alliance on Management & Nutrition has published an excellent fact sheet that specifically addresses the legal dosages, duration of therapy, and withdrawal times for antibiotics that legally can be added to milk replacer.
  

• Decoquinate (Deccox®) and Lasalocid (Bovatec®) – Both of these products address coccidiosis in calves and cattle, either by destroying the causative organisms, or preventing them from growing. These products do not require a VFD, and have no preslaughter withdrawal when used according to label.

Beyond these medications, there currently are many other products that are added to milk replacer in an effort to reduce disease and increase calf performance. These include – but are not limited to – prebiotics such as yeasts and mannan oligosaccharides (MOS); probiotics; and essential oils. These non-medication additives are not regulated by the FDA, and do not have withdrawal times.

Be careful when using a combination of medications and/or additives, as sometimes their efficacy can be cancelled out. For example, feeding an antibiotic with a probiotic can lead to the antibiotic destroying the beneficial bacterial organisms in the probiotic.

In other cases, too many additives can result in toxic levels of some ingredients like vitamins A and D. Always read the label on any products you add to milk replacer, and work closely with your nutritionist and veterinarian to assess your calves’ challenges and choose milk replacer additives and medications accordingly.

When the VFD originally was issued, it produced sweeping change in the livestock industry, and many wondered if we could successfully raise calves without the antibiotic options we previously had at our disposal.

Fortunately, we are doing better than ever at managing calves and providing them with the nutrition they need to stay healthy. Improved colostrum delivery; higher-quality milk replacer ingredients; accelerated feeding programs; advances in housing and sanitation; and more effective vaccines all have allowed us to proactively support calf health and performance, without the protective “blanket” of feeding subtherapeutic antibiotics.

While antibiotics and other medications still have an important place in raising healthy calves, today’s industry approach is focused on supporting the whole animal and naturally preventing sickness and disease. We have moved away from using antibiotics as our first line of defense. They now are one of many instruments in our toolbox that we use to raise healthy calves, and only in very precise applications.