LINDELL BEACH, B.C. – New research is finding better ways to protect lambs from parasites.
They are using copper oxide gel capsules to reduce the need for conventional deworming medications, frequent rotational grazing and regular checks of animals’ eye colour to monitor health.
Animal scientist Joan Burke of the U.S. Department of Agriculture and researchers from the Southern Consortium for Small Ruminant Parasite Control have been working on ways to reduce the use of conventional parasite controls in favour of organic management systems that meet the consumers’ preferences for less chemical residues in meat.
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The problem parasite in lambs is the blood sucking barber pole worm Haemonchus contortus, which can cause severe anemia.
This parasite, named for the spiralling of its white, egg-filled ovaries around blood-filled intestines, costs farmers and ranchers millions of dollars in production losses annually worldwide.
Animals shed the worm’s eggs in their manure and the hatched larvae are eaten by other livestock.
The research team tested 71 lambs that had been naturally infected with the worm.
It was the first rotational grazing study of its kind using worm-infested lambs.
Researchers administered gel capsules filled with copper oxide wire particles only to lambs whose inner eyelid colour was a medium pale red, or Stage 3, on an eye colour chart that was used as part of the clinical, on-farm system for detecting anemia.
“The colour of the ocular membrane indicates how anemic an animal is and the anemia is assumed to be caused by H. Contortus,” Burke said.
“The colour score (one is red, or healthy, and five is white, or anemic) is negatively correlated to the packed cell volume and positively correlated to fecal egg counts. We recommend always treating fours and fives and leaving animals with ones and twos untreated.”
Whether animals with a three score get treated depends on factors such as the productive stage of the animal, she said.
The copper oxide wire particles (COWP) could be used in capsules or mixed in feed to control gastrointestinal nematodes in sheep and goats.
COWP has a short-term effect and is active only against the adult stage of the worm.
The particles lodge in the folds of the abomasum, or true stomach, and appear to act directly on the cuticle or outer layer of the worm.
Burke and her team found that the particles eliminated the need for conventional dewormers in all but one animal.
Caution was exercised when administering the COWP to sheep because of their susceptibility to copper toxicity.
She said the protocol was sometimes not effective because the rumen was not functioning properly or the animal was sick.
Researchers monitored the effectiveness of rotational grazing by grazing some of lambs on Bermuda grass in the same pasture all season and rotated others every 3.5 to seven days.
“The longer the time frame in which animals return to the grazed pasture, the better,” Burke said.
“If farmers can rotate among two plots, that is an improvement over one plot. So the more plots a farmer has, the better.”
In the rotational grazing study conducted with lambs using a poor quality grass (Bermuda grass during summer months), lambs were rotated among 10 plots in one acre the first year, four plots in one acre the second year, and returned to the original plot 35 or 28 days later, respectively.
In both studies, fecal egg counts and the incidence of deworming was lower in lambs on these rotational plots compared to those that rotationally grazed similar forage of similar height.
If farmers can add another species like cattle or horses to their sheep or goat grazing pasture, this adds another means to remove infectious parasites, since cattle remove them for sheep and sheep remove them for cattle.
“There are no real critical guidelines because it is dependent on forage quality, forage height and the number of pastures available,” she said.
Burke said farmers are receptive to the outcome of the studies.
“By having many different tools to choose from (forages including sericea lespedeza, pasture management, nutrition, resistant genetics, multi-species grazing, COWP), farmers can adopt tools that are convenient for them, their farm or their lifestyle.”
Other approaches to tackle the parasite are in the research stages.
“For example, if we use some of these techniques, will other parasites like the bankrupt worm or the brown stomach worm become a problem? If so, we need to find nonchemical approaches for them since many of our approaches are specific for H. contortus.”
Copper oxide wire particles are sold in commercial livestock products to treat copper deficiency in cattle but Burke said the pre-packaged boluses would need to be re-packaged into boluses of one gram for lambs younger than 12 months or two grams for older animals. Farmers should consult with a veterinarian before selecting a dose.
“Using an integrated approach or using as many management tools as possible for parasite control will help to minimize worm problems no matter what the species of worm,” Burke said.
