Devising a proper deworming plan | TSLN.com

Devising a proper deworming plan

Dave Barz, DVM

Finally the humidity has decreased and the temperature feels less tropical. The corn is growing rapidly and the pastures remain green. It is hard to believe that now is the time to plan and implement your worming program.

I remember 20-plus years ago when many educated people argued it was not economical to deworm cows. They could not show significant increase in weight gain on dewormed cows over non-dewormed. Feed was plentiful and inexpensive, and as long as we had plenty we didn’t care how much it took to maintain our herds.

The advent of pour-on antiparacitides changed everyone’s strategy. Most producers chose to pour their cows because it was simple even though it cost about $7.50 per head. With the release of generics now we can accomplish this procedure for about $.70 per cow – quite a price decrease.

Most of our deworming data on the pour-ons was completed before they were released. Initially they showed excellent deworming rates, but over time these levels of control have decreased. Today some trials show these pour-ons to be only 50 percent effective. Therefore if you are relying on a fall or spring pour-on dewormer, you are leaving a lot of parasites in the host. These egg laying adults spread the infestation at greater levels in your herd.

The parasites seem to develop resistance to the pour-ons rapidly. This is a result of two problems with pour-ons.

1. Absorption of the paraciticide is slow and requires several days to reach levels detrimental to the parasite. Then the level slowly decreases as it rose.

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2. Absorption of the chemical through the hide is variable as a result of temperature precipitation and other variables. This also results in prolonged low levels of the antiparaciticide.

When the parasite is exposed to low levels of the paraciticide some will develop resistance to the chemical. These are the ones that persist after the treatment and re-infect your herd.

The cows carrying these resistant parasites go to pasture and shed eggs. The higher the population in mama cows, the more eggs shed on the pasture. These eggs then hatch and release juvenile parasites on the grass. Many of these are ingested by cows and calves, re-infecting the whole herd. Some of these juveniles will over winter in the soil in the pasture and re-emerge the next spring to re-infest your herd. This means we must deal with a pasture contaminated with large numbers of juveniles next spring.

When deworming cows and calves we prefer oral over injection and either over pour-ons. You must devise a deworming plan to:

• Decrease parasites carried to pasture.

• Prevent as much pasture contamination as possible.

• Ensure the proper response to vaccines and diseases.

Your veterinarian, nutritionalist or extension specialist can help you devise a simple strategic deworming program which fits into your cattle movements as well as interrupting the parasites life cycle. Your investment in a workable program will greatly increase the efficiency of your herd.

Finally the humidity has decreased and the temperature feels less tropical. The corn is growing rapidly and the pastures remain green. It is hard to believe that now is the time to plan and implement your worming program.

I remember 20-plus years ago when many educated people argued it was not economical to deworm cows. They could not show significant increase in weight gain on dewormed cows over non-dewormed. Feed was plentiful and inexpensive, and as long as we had plenty we didn’t care how much it took to maintain our herds.

The advent of pour-on antiparacitides changed everyone’s strategy. Most producers chose to pour their cows because it was simple even though it cost about $7.50 per head. With the release of generics now we can accomplish this procedure for about $.70 per cow – quite a price decrease.

Most of our deworming data on the pour-ons was completed before they were released. Initially they showed excellent deworming rates, but over time these levels of control have decreased. Today some trials show these pour-ons to be only 50 percent effective. Therefore if you are relying on a fall or spring pour-on dewormer, you are leaving a lot of parasites in the host. These egg laying adults spread the infestation at greater levels in your herd.

The parasites seem to develop resistance to the pour-ons rapidly. This is a result of two problems with pour-ons.

1. Absorption of the paraciticide is slow and requires several days to reach levels detrimental to the parasite. Then the level slowly decreases as it rose.

2. Absorption of the chemical through the hide is variable as a result of temperature precipitation and other variables. This also results in prolonged low levels of the antiparaciticide.

When the parasite is exposed to low levels of the paraciticide some will develop resistance to the chemical. These are the ones that persist after the treatment and re-infect your herd.

The cows carrying these resistant parasites go to pasture and shed eggs. The higher the population in mama cows, the more eggs shed on the pasture. These eggs then hatch and release juvenile parasites on the grass. Many of these are ingested by cows and calves, re-infecting the whole herd. Some of these juveniles will over winter in the soil in the pasture and re-emerge the next spring to re-infest your herd. This means we must deal with a pasture contaminated with large numbers of juveniles next spring.

When deworming cows and calves we prefer oral over injection and either over pour-ons. You must devise a deworming plan to:

• Decrease parasites carried to pasture.

• Prevent as much pasture contamination as possible.

• Ensure the proper response to vaccines and diseases.

Your veterinarian, nutritionalist or extension specialist can help you devise a simple strategic deworming program which fits into your cattle movements as well as interrupting the parasites life cycle. Your investment in a workable program will greatly increase the efficiency of your herd.

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