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Strategic Worm Drenching Saves Money

Strategic drenching of all sheep with a double summer drench (November/December and January/February), with a move to 'low-worm' pastures, has been recommended for many years.

By Department of Primary Industries - 25th February 2004 - Back to News

This is to take advantage of pasture drying and the consequent destruction of worm larvae by lack of moisture and exposure to ultra violet light. Worms occur either on pasture or in the animals. The drench fixes the animal problem and the environment the pasture problem.

In drier climates, a second summer drench may not always be necessary. There is, however, no clear guideline as to whether a second summer drench is, or is not, required. This is because poor nutrition, summer rains and other management factors can result in higher worm burdens than might be expected.

The only way to decided on whether to give a second summer drench, is by doing a 'WormTest'. The test counts the average number of worm eggs that are present in each gram of faeces passed by sheep in a particular mob.

This is used as a guide as to whether or not to drench.

Mobs with less than 100 eggs per gram don't require drenching. Egg numbers of 100 - 200 per gram could indicate the need to drench but, in some situations, drenching may be put off for another 4-6 weeks, when egg counts can be re-checked.

WormTest kits are available free direct from the testing laboratories as well as from Stock and Station Agents, private veterinarians and DPI.

The cost of a basic WormTest is $30 or less. The exact cost can be obtained from the laboratory. Results are usually available on the same day that the samples arrive at the laboratory.

Samples can be collected for WormTest by running a mob of sheep into the corner of a paddock, holding them there for 10 minutes, collecting 10 samples of freshly deposited droppings and placing them in the container provided. Sampling early in the morning, when it is generally a little cooler, may make it easier to pick out the fresh droppings.

If a second summer drench is to be given, then each sheep must be given the correct dose. The biggest sheep in the mob should be weighed and the dose rate calculated for the heaviest sheep. The drench gun should also be checked to see that it is delivering the amount that it is set to deliver.

Reducing feed intake, but not the water intake, for 24 hours before drenching can increase the effectiveness of certain drenches (ie -mectin type drenches and the white -bendazole drenches). This is not recommended for heavily pregnant sheep, stressed sheep or sheep in poor condition.

After drenching, sheep should be moved to 'low worm' pastures.

Further information can be obtained from your local DPI District Veterinary Officer or Animal Health Officer, or from your local veterinary adviser.

PLANNING FOR DRYING OFF

Research indicates that intramammary infections picked up in the dry period can present as both clinical cases near calving, and also later in lactation. Good planning and strategies at drying off will play an important role in the control of your clinical cases during the following lactation.

Now is an ideal time to consider and plan your treatment options at drying off. These options may include:

1. ‘Blanket’ strategy- treat all quarters of all cows with antibiotic Dry Cow Treatment.

2. ‘Selective’ strategy- select the infected cows and only treat these cows with antibiotic Dry Cow Treatment.

3. ‘Combination’ strategy- use antibiotic Dry Cow Treatment in all quarters of infected cows and teat sealant in all quarters of non- infected cows.

Selective and combination strategies should only be used where at least three cell counts have been done during the lactation. Farms that do not have this data should use Blanket Dry Cow Treatment.

The key questions to consider when choosing between these options are:

• How many cows are infected? - Do more than 30% of your cows have their highest cell count above 250,000 cells/ml? Or did any milk cultures show Strep agalactiae?
  If so, then ‘blanket’ dry cow strategy is most likely to give the most cost effective approach.

• Is there a significant risk of new infections in the dry period? - Do more than 5 cows per 100 suffer from clinical mastitis in the first month of lactation? Was there a significant Strep uberis problem last year? Are you likely to have more than 5% of cows dripping milk prior to calving next year?

If the answer to any of these questions is yes, it’s worth considering either a ‘blanket’ or ‘combination’ treatment strategy.

Teat sealants are a non-antibiotic, non-irritant, insoluble product for use at dry off. As the product resides in the teat for the dry period, it protects the gland from invasion by bacteria. They do not cure existing infections and must be inserted after careful disinfection of the teat end.

Plan to dry cows off in manageable batches - having an extra pair of hands can reduce the stress all round and probably achieve a better result!

Don’t forget to mark cows clearly that have been dried off, especially those with dry cow antibiotics! Record keeping is important.

Countdown Downunder Farmer Short Courses can help you learn more about drying off issues, controlling your cell count and mastitis levels. You will also have the benefit of working with vets and dairy advisers from your local area to work-up specific plans for your farm.

Source: http://gippsland.com/

Published by: news@gippsland.com