UNIVERSITY PARK, Pa. — Two changes in federal regulations will affect medicated feeds, including milk replacer, beginning early next year. The first change adjusts the ratio of neomycin sulfate to oxytetracycline (brand name Terramycin) that can be used in making medicated feeds. The old ratio was 2 parts neomycin sulfate to 1 part oxytetracycline; the new ratio is 1 to 1.
This drug combination is often called neo-terra or NT on product labels. This change will increase the cost of medicated feeds, because Terramycin is more expensive than neomycin. The second change affects the dose and length of time that antibiotics can be fed. The updated regulations still allow NT to be used for improving feed efficiency or for treating diarrhea and pneumonia caused by bacteria.
In calves under 250 pounds, NT can be fed in milk replacer or starter grain. For improved weight gain and feed efficiency, NT is approved at 0.05 to 0.1 mg per pound of body weight. Assuming a 100-pound calf eating 1 to 1.25 pounds of milk replacer powder per day, this rate works out to 16 to 20 grams of NT per ton of milk replacer.
For comparison, the old rate was 300 g/ton. Recent research has shown little improvement in feed efficiency at 600 g/ton.
Bottom line: it does not look like feeding low levels of NT to improve feed efficiency will be cost-effective. For treatment or control of diarrhea caused by E. coli, NT can be fed to calves under 250 pounds at a rate of 10 mg/lb of body weight. But, it can only be fed for up to 14 days, which means that feeding medicated milk replacer from birth to weaning will no longer be permitted.
For our example calf weighing 100 pounds and eating 1 to 1.25 pounds of milk replacer powder each day, the treatment rate works out to a concentration of 1600 to 2000 g of NT per ton of milk replacer. For comparison, the old approved rate was 600 to 1200 g/ton.
When needed for treatment, the new higher rate should be effective, but it will probably be cost prohibitive to feed the new higher rate to all calves on a regular basis. Keep in mind that NT is not effective in treating diarrhea caused by rota or corona virus or by coccidia. The company that produces NT has already switched from a 2 to 1 to a 1 to 1 ratio, and it is expected that most milk replacer manufacturers will run out of 2 to 1 NT by March 1, 2010.
Milk replacer with the 1 to 1 ratio of NT as well as an “add pack” of NT will likely be available after March. The add pack approach will allow you to continue feeding a standard non-medicated milk replacer and mix in NT for calves that need treatment. Medicated milk replacer and starter should not be fed to veal calves or bulls that may end up as bob veal. The slaughter withdrawal period for NT is 5 days.
If you have been relying on medicated milk replacer, now is the time to consider other options. Feeding non-medicated milk replacer and only treating calves as needed allows more flexibility and should save you money.
Various additives can be effective antibiotic alternatives in milk replacer, or you could consider feeding pasteurized waste milk. Whatever feed you choose, be sure to provide calves enough nutrients to meet their needs, protect them from environmental stress, and limit their exposure to pathogens.
(Coleen Jones, is a Research Associate and Jud Heinrichs, Professor of Dairy and Animal Science at Penn State University.)