Skip to main content

News and Media

Open Main MenuClose Main Menu
Photo of boy with sheep

Veterinary Viewpoints: Old McDonald Had a Farm

Tuesday, August 17, 2021

Media Contact: Derinda Blakeney, APR | College of Veterinary Medicine | 405-744-6740 |

Old McDonald did indeed have a farm and what made his farm so entertaining to us as children, and perhaps now as we sing it with the children in our lives, was all the different animals he had. Multispecies farms are common around Oklahoma, and they do bring joy as the song indicates. There are, however, a few considerations when multiple species of animals are housed in proximity to one another. Certain medications, feeds and feed additives that are advantageous to the health of one species can actually be detrimental to other species.

Here are the top five dangers on a multispecies farm:

  1. Copper is an important trace mineral. It is required by all animals for a variety of important biological processes. The amount of copper required by livestock species varies widely. Sheep are by far the most sensitive livestock species to copper. While sheep do require a small amount of copper in their diets, providing them almost any feed that isn’t labelled for sheep is potentially dangerous. Goats are slightly more tolerant of copper than sheep and require a little more in their diet, but we see copper toxicity in goats as well. As a rule, feeds for swine and poultry are the most dangerous, followed by horse feeds and cattle feeds. Feed only a feed that has a picture of your animal on it, and don’t let other species access that feed.

Remember, anything that is eaten shows up in the feces. So, the manure of these higher copper-tolerant species is also high in copper. I consulted once on a case of several sheep deaths on a farm that was adjacent to a swine operation. The sheep were in a pasture below the swine barn and there was runoff to the sheep pasture. The grass along the fence between the two was lush from all that fertilization and the sheep would graze down that fence line and die from copper toxicity.

Feeds are not the only sources of copper on an operation. Loose and block trace minerals, injectable trace mineral supplements, copper boluses, algaecides (copper sulfate), and other farm chemicals may also contain copper and be toxic.

  1. Ionophores are a class of feed additive drugs that promote growth and help control coccidia in ruminants such as cattle, sheep and goats. The ionophores include such drugs as monensin (Rumensin) and lasalocid (Bovatec). Their usefulness ends with the ruminants, though, as they are fatal to horses. There are many stories of horses being accidentally fed or breaking in and consuming ionophore-containing cattle feeds. The ionophores cause acute heart failure. Even traces of these drugs can be fatal, with some reports of horse deaths coming from feed mills that mixed horse feed after cattle feed in the same mixer without adequately cleaning it.
  2. Grains, especially corn, are used in the feeding of all livestock species, so how can they be problematic on a multispecies farm? Let’s talk about the digestibility of grains, using corn as an example. Corn comes to us for feeding in a variety of forms: whole corn, steam flaked, rolled, cracked, ground, etc. The less processing that is done to corn, the less digestible it is. You know this because you often see whole kernels of corn in the manure of animals on diets with whole corn. With increased processing, however, more of the starch of the corn is exposed, making it more digestible, but also potentially more dangerous. With increasing processing and starch exposure, the risk of grain overload or rumen acidosis increases. So, whole corn is much less likely to cause grain overload and rumen acidosis than corn ground much more finely for poultry or pig feed, for example. If a steer were to break into a bin of whole corn, he may get a bad bellyache that requires treatment, but if he breaks into chicken or pig feed corn, he could rapidly bloat and die because of the extra processing.

I recently saw one of the worst cases of rumen acidosis I have ever seen in a beloved pet goat because she broke into the feed room and ate a large amount of waterfowl feed. She came in to us on Christmas morning unconscious and required a week of hospitalization to recover. The fine corn grind used in poultry and wild bird feeds is extremely dangerous to cattle, sheep and goats.

  1. Alfalfa is an important high-protein feed on many farms fed to a variety of species. While it is safe for most of our common domestic livestock species, animals who should never be exposed to alfalfa are male sheep and goats, especially if they are pets or miniature breeds, such as Nigerian Dwarf or Pygmy. Male sheep and goats are at high risk for bladder stones that can become lodged in the urethra, causing rupture of the urethra or bladder and kidney failure. Bladder stones can also be formed in these males from eating high-grain diets as well, but the stones created from alfalfa-based diets are by far the most difficult to treat. If you are feeding grains and alfalfa to horses or cattle, it is best to keep male sheep and goats away from those feeders.
  2. Avermectin class dewormers includes those products containing ivermectin (Ivomec and generics), doramectin (Dectomax), moxidectin (Cydectin) and eprinomectin (Eprinex, LongRange). Many equine paste dewormers of various brand names contain an avermectin dewormer — be sure to read the labels. Farm dogs are the concern here. As you know, when you are giving a dewormer, especially an oral paste to a horse, some gets dropped on the ground. In addition, the drug gets excreted via the feces and is present in manure on the pasture. Some dog breeds, particularly white-footed herding breeds, are very sensitive to ivermectin and should never be exposed to these drugs as they can cause damage to the nervous system and be fatal. Most fatal farm dog exposures stem from paste dewormers that drop onto the ground during administration or from eating the manure of a treated animal, as the drugs are excreted into the feces.

Here are some safety tips for caring for multiple animal species:

  1. Keep each feed in a bin with a secure lid inside a secure room. Make sure that the bin is clearly labelled with the species for which the feed is manufactured.
  2. Separate species at feeding time to limit other species from sneaking feed or picking up feed dropped on the ground.
  3. Store ionophore-containing feeds in a completely separate area from horse feeds.
  4. Review safety and health concerns with ranch help and ranch sitters so they are aware of the dangers. Provide clear, written instructions on feeding, including exactly how much to feed.
  5. Keep stalls picked and cleared of manure.
  6. Always read the label of any supplement or medication you intend to use. Never use a product in a species that is not on the label unless directed to do so by your veterinarian.
Meredyth Jones
Meredyth Jones

About the author: Meredyth Jones, DVM, MS, DACVIM, is an associate professor in food animal medicine and surgery at Oklahoma State University’s College of Veterinary Medicine. A Diplomate of the American College of Veterinary Internal Medicine (Large Animal), she also owns Large Animal Consulting & Education.

Veterinary Viewpoints is provided by the faculty of the OSU Veterinary Medical Teaching Hospital. Certified by the American Animal Hospital Association, the hospital is open to the public providing routine and specialized care for all species and 24-hour emergency care, 365 days a year. Call 405-744-7000 for an appointment or more information.

OSU’s College of Veterinary Medicine is one of 32 accredited veterinary colleges in the United States and the only veterinary college in Oklahoma. The college’s Boren Veterinary Medical Hospital is open to the public and provides routine and specialized care for small and large animals. The hospital offers 24-hour emergency care and is certified by the American Animal Hospital Association. For more information, visit or call 405-744-7000.

Back To Top
SVG directory not found.