By ANN HINCH
Assistant Editor

ST. LOUIS, Mo. — Livestock feed manufacturers may not always formulate the medicated feed additives (MFAs) they put in their final products, but that’s no reason not to have a basic understanding of what they are and how they work.

This was the message from Dr. Denny Hausmann, a veterinarian employed by Alpharma Animal Health in Colorado, during the Feed Industry Institute in St. Louis, June 14-17.

Sponsored by the American Feed Industry Assoc., the institute is a biennial course to educate newer employees of member industries on the basics of animal nutrition. This year was the first time the institute has moved out of Chicago in its 30-year history; approximately 125 participants attended and led sessions at the four-day mini-university.

Hausmann, one of the industry expert “professors” presenting, said feed manufacturers should learn about MFAs if for no other reason than if a feed product fails, their supplier may not be the only one taking the blame. “Sometimes, we’re both going to be judged on how well these perform in feed,” he pointed out.

MFAs are “pharmaceutically-active substances that are administered to the animal via feed” and are regulated by a branch of the U.S. Food and Drug Administration (FDA). Hausmann said the FDA sets standards and processes for reviewing antibiotics for animals the same as for humans, since they are judged on safety to the animal itself and to humans consuming livestock products.

The feed industry selects from 72 trade-name additives, as of 2008. Of these, at least 38 are antimicrobials, 11 are parasiticides and one is a hormone. Some can cross species, but to give an idea of how many are used in some livestock, 28 can be used for cattle, 23 for turkeys and 27 for swine.

Another reason the industry should be mindful of how these drugs perform is so they will distribute the material evenly throughout feed. Hausmann said test samples in a mill in the same batch of feed, over the course of one day, have been known to show big inconsistencies in the level of additives, which should have been similar in each batch.

This is so an animal eating one ration from the same supply as another isn’t getting a far larger or lower dosage. “We need to be on top of the ball game,” he said, if a manufacturer is going to be considered trustworthy within the industry.

Outside the industry, there are other kinds of controversy, such as widely differing attitudes on the use of MFAs. This includes broad criticism of and worry about how their effect on livestock tissue could harm humans – and the animals themselves.

Hausmann said MFAs are used as growth promotants, by improving intestinal cell health and by cutting down on pathogens – microorganisms causing illness – directing more nutrients toward growth rather than using the immune system so much. He said they also make adjustments to volatile fatty acids in the gastrointestinal tract, resulting in increased average daily gain.
“It’s pretty hard to turn a Shetland pony into a hunter jumper,” he said. “But you can help it be the best Shetland pony he can be.”
MFAs are also important to parasite control. Some bacteria and other tiny creatures are beneficial in an animal’s gut, but many are not. Feed comes in varying formulations of medication even for the same kind of livestock, but the main consideration, as Hausmann phrased it, is to “get the right amount of drug to the bug.”

These “bugs” can be aggravated by various factors, including stress. Feed makers need to be aware of these. They also need to be aware of legal aspects such as, if an animal has more than one medical problem, feed designed to help with one condition may be judged on efficacy – or lack thereof – even if the feed is formulated properly, if it doesn’t do its job because of the other medical condition(s).

That MFAs are necessary to the livestock industry isn’t always an easy message to get across to the general public, Hausmann said. Part of the problem, he said, is an incomplete understanding by people on what antibiotics do – such as preventing, controlling and treating disease.

While the livestock industry and related businesses should be worried about excessive antibiotic use affecting animal and human bacterial resistance, he said there are other factors which can affect resistance besides medication and MFAs. Those in the industry should be willing to respond in an ethical manner to questions from the public, and also be able to explain the role of antibiotics.
“It’s difficult to keep animals from gaining weight when they are healthy,” Hausmann said. “Therein, I think, lies some of our conversation with the public.”