Ag Notes: Deworming cattle?

Published 8:16 am Tuesday, October 3, 2017

Although specific estimates are not available, economic losses from worm parasites infections of cattle can be significant in Kentucky.

The extent of internal parasite problems is usually related to management  practices that increase exposure, whereas ongoing preventive management practices will minimize losses caused by parasite infections.

Calves under one year of age are more susceptible than older cattle. Older cattle frequently have been exposed to the parasites and developed a degree of

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immunity, but the cow herd remains the major source of initial exposure of the calves.

Adult worms in the gut of cattle produce eggs that are passed in the manure. The eggs hatch, producing immature larvae that develop and move up onto the pastures grasses.

Infective larval forms of the worms may be present in large numbers on the growing forage. Some of the eggs can survive the winter and hatch out with warm weather.

Temperatures between 60º and 80º F and at least 2 inches of rainfall per month

provide excellent propagation conditions. Feed bunks or waterers contaminated with manure can be a source of exposure to the larvae.

The need to deworm calves during the summer depends strictly on the degree of contamination of pastures or lots. Use of the same pastures year after year or high densities of grazing cattle can result in heavily contaminated forage. The number of times calves should be wormed during the spring and summer depends on the level of exposure and reinfection.

Internal parasites have the greatest impact on rate of gain when cattle are on low energy levels, which are typical of receiving or backgrounding rations.

Timely, “strategic” deworming prior to the grazing season will greatly reduce the subsequent contamination of pastures during the grazing season.

Pregnant cows can be dewormed in the fall. These cows can be expected to winter better, have a high conception rate the next breeding season and wean heavier calves.

For more information contact the Boyle County Cooperative Extension Service.

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Jerry Little, County Extension Agent for Agriculture/Natural Resources