A number of people across the Ozarks are getting into small sheep flocks and goat herds; that’s according to Dr. Charlotte Clifford-Rathert, University of Missouri Extension state small ruminant specialist at Lincoln University. “Some people are expanding into larger numbers to accommodate multi-species grazing with their cattle,” Clifford-Rathert told Ozarks Farm & Neighbor.
Parasite control is important with small ruminants but, she said, “you don’t want to do a complete herd deworming. You just want to deworm those for which it’s necessary because they’re losing weight, or have symptoms of parasites, or their fecal examination has shown that they have a high count of parasite eggs.” Other symptoms may include a poor hair coat, a sickly look and, for younger animals a potbelly. Producers should evaluate each animal individually to determine which need treatment, and which ones have a strong enough immune system to handle the problem on their own.
The gastrointestinal parasites most likely to have the most economic impact on production are known as the HOTC complex. They include the barberpole worm (Haemonchous contortus) and the brown stomach worm (Ostretagia), which reside in the abomasum or fourth stomach, and the bankrupt worm (Trichostrongylus) and coccidian (Eimeria spp.), which populate the small intestine.
The barberpole worm is the biggest challenge, according to Dr. David Fernandez, University of Arkansas Extension livestock specialist at Pine Bluff. “The barberpole worm has developed resistance to all of the dewormers that we use,” he told OFN. “The problem is the resistance varies by farm, so if you’ve been using one anthelmintic on your farm and the barberpole worm has developed resistance to it you’ll have to switch classes, whereas your neighbor’s farm may have been using a different anthelmintic and developed resistance to that on their farm.” Rather than rotate dewormers, he recommends using one class of chemistry until it’s no longer working on your farm, and then making a switch.
A common way to determine the level of infestation is to assess what’s called a FAMACHA score, which involves checking the color of the red tissue that surrounds the eyeball against a chart. “As that becomes more pale, it indicates anemia and once they reach a certain point on the FAMACHA score, you would treat those animals,” Fernandez said.
That also provides a starting point for conducting a fecal egg count, which determines whether your dewormer is working. Take a fecal sample at the time of treatment, and again 2 weeks later, to determine how much the eggs have been reduced. Fernandez said, “Once the reduction starts to drop below about 90 percent, you’re seeing resistance and when you get below 50 percent, you’re not having a clinical effect anymore; you’re not reducing the worms such that your animal is going to recover. If your dewormer is still working, in 2-3 years you’ll want to do the check again; if it’s not working, you’re going to want to switch dewormers and do the test again, to make sure that your new dewormer is not one to which your worms are also resistant.”
The barberpole worm typically starts causing problems in late spring, when conditions get warm and moist. Fernandez said during drought the worms dry out and die very quickly, but a sudden rain can cause the mass release of the eggs stored in feces on your farm. One way to control infestation levels is pasture rotation; the worms’ lifecycle is 21 days from the time they’re ingested until they begin to produce eggs and then, although a number of variables come into play, it takes about 5 days for them to hatch out and start migrating out onto grass to renew the cycle. Fernandez said, “If you can have your animals on pasture for a week, then rotate them to a new pasture and not have them come back for 21 days or more, it’s less likely that you’ll see infestations and what you do get will be a lower rate of infection.”
Other control methods include multi-species rotation – the larvae do not survive inside a cow – and maintaining a high grazing height. The barberpole worm only crawls 2-3 inches up the blade of grass, so if the grass is at least 4 inches in height you’ll reduce the rate of infection, although Fernandez said that varies with the species: “Goats graze from top down; sheep, on the other hand, like to put their nose down on the ground, so it’s very difficult to keep them from getting some of them. But they’re also more resistant to the parasite than goats are.” Forages high in tannins, like sericea lespedeza or chicory, can also help to eliminate the barberpole worm from the animal’s digestive track.
