Most adult sheep have low worm egg counts in early summer and a drench at that time is not warranted; delaying a drench until late March or April allows some less-resistant worms to survive.
Drenching too often or not following a set program, is also a problem. As a general guideline, non-breeding sheep should need a single drench a year, and lambing ewes and weaners two drenches. Please keep in mind that conditions on your property and in your region will ultimately affect how many drenches you need.
Weaning drenches
Drenching lambs weaned at 12-14 weeks after lambing commenced is recommended because lambs have not developed their natural immunity to worms at this stage.
Regarding lambs, they generally will need to be wormed. Traditionally, people have been worming lambs when clinical signs appear (i.e. scouring, wasting, etc.) or just every three weeks.
Young lambs can be exposed to drench in utero or from the day they are born. Long-acting drenches cause changes in the rumen microbiome.
Pregnant women who come into close contact with sheep during lambing or other farm animals that are giving birth may risk their own health, and that of their unborn child, from infections that such animals can carry.
Traditionally ewes are given a drench pre-lambing to help control the “periparturiant rise”. This is when, around lambing time, a ewe's natural immune defences are reduced and their normal capacity to remove worms from pasture is lost.
Do NOT use in pregnant ewes in the first trimester of pregnancy.
Moxidectin is a member of the 3-ML anthelmintic class. Moxidectin has been shown to be safe for use in pregnant, lactating and breeding animals.
Deworming for Stomach and Intestinal Worms: The clear drenches ivermectin and levamisole are by far the most effective in controlling stomach and intestinal worms. Stomach worms such as haemonchus contortus are blood suckers and cause anemia in sheep.
The Dorper sheep is fast becoming a favourable breed in areas of organic production (pastoral areas) as they have characteristics that result in no need for drenching or other treatments.
Levamisole is a short acting clear drench. Levamisole is still highly effective against barber's pole worm and Nematodirus on most properties. Nematodirus is often a problem after drought or in lambing paddocks as the egg is resilient and can survive in hot, dry conditions for long periods.
Normally sheep should be treated every three to four weeks. Keep in mind that worms may develop resistance to a drug if exposed frequently. Lower stocking rates will reduce the intensity of the deworming program. Fewer sheep result in fewer shed worm eggs within a given area, and thereby reducing parasite loads.
Overdosing sheep or lambs with drench or incorrect pre or post drenching management can be fatal so it is important to consider how you drench as well as 'when' and 'what with'. Key drenching principles include: Always read the product label for both dosage and safety information.
You should also lessen the frequency of feeds gradually. During the first and second periods feed sheep daily, then introduce intermittent feeding. By the fifth or sixth period, put the feed out once every 3–4 days.
B - Keep them off pasture for 24-48 hours so that all the worm eggs have been passed.
Traditionally, most flocks have wormed ewes at lambing. This practice is designed to combat the drop in immunity to worms that ewes experience from around 2 weeks before lambing to 6 weeks afterwards.
“When ewes and lambs are kept in for any period of time after lambing they should be drenched when put out to grass. That is providing this is within the period of the peri-parturient relaxation of immunity, which runs for about six weeks after lambing.”
Thin ewes, with body condition scores of less than 3, should gain weight to maintain their pregnancy and target a body condition score of 3 to 4 by the time they lamb. This can be accomplished with high-quality forage or by supplementing their diet with concentrates (i.e. grains).
Safe for use in pregnant ewes, rams and lambs. Administer as an oral drench. Do not treat sheep within 11 days of slaughter. Ingredients: Ivomec® Sheep Drench contains ivermectin 0.08% Solution.
Ivomec (ivermectin) sheep drench is the preferred and primary product used to deworm sheep by most shepherds.
Sheep farmers may want to consider treating their ewes prior to lambing with a long-acting wormer, after a study has found it reduces the parasite burden in lambs and improves growth rates.
However, evidence with sheep is less clear; one study demonstrated feeding did have an effect (1): 65% of lambings occurring within 4 h before, and 8 h after feeding – therefore feeding in the morning was recommended.
Colostrum: Colostrum, or a colostrum supplement, should be fed to lambs when a ewe does not have enough for her lamb(s). Producers can obtain colostrum from a healthy ewe on their farm who produces more than her lambs need.
After lambing, move the ewe up to full feed (6-7 pounds) of a diet containing 65% total digestible nutrients and 15% crude protein (when suckling twins). An example diet that would meet this requirement could be 4 pounds of moderate quality alfalfa hay and 2 pounds of whole corn.