1. WEIGH – DON’T GUESS
Underestimating the weight of sheep is a common cause of under dosing. Select and weigh the biggest sheep in the group to determine the correct dose. If there is a wide range of weights, consider splitting the group, then weigh the heaviest in each section. Don’t forget to check that the weigh-crate is accurate before you start!
2. CALIBRATE AND MAINTAIN THE DRENCH GUN
Always check the gun is delivering the right amount before you drench. Use a calibration pot or remove the plunger from a 10ml syringe, put your thumb over the end and squirt the dose into it, making sure you have got rid of any air bubbles first. Adjust the gun until the dose delivered is correct. Drenching guns should also be well maintained and replaced regularly. Clean with warm soapy water after use and check springs and tubes to make sure there are no kinks that will form air bubbles.
3. DRENCH CORRECTLY
The drenching technique is a vital part of ensuring that the wormer does its job effectively. Make sure the sheep are properly restrained and can’t leap around when you are drenching, so they swallow the whole amount. Sheep can also suffer serious injury, or even death, if they are unrestrained and the gun penetrates the tissues at the back of the mouth. Place a hand under the head and tilt slightly to the side. Slot the nozzle in the gap between molar and incisor teeth and then over the back of the tongue. You must get the nozzle over the back of the tongue. If the wormer is just put into the mouth, it will by-pass the rumen as it escapes down the oesophageal groove. This is particularly important for white (1-BZ) drenches.
Withholding Food
Research has shown that the efficacy of the white (1-BZ) and clear (3-ML) drenches can be improved by withholding food for 12-24 hours before treatment.
Storage
Wormers should be stored securely, away from direct sunlight. Check the ‘use by’ date and once open use within the time shown on the packaging. Shake white (1-BZ) products well before use.
And remember…….
No matter how often you use a wormer, always read the instructions. Recommended dose rates and withdrawal periods do change.