Drenching lambs at weaning

On a conventional sheep and beef farm more time, energy and effort are likely to be invested in drenching lambs than in any other class of stock. It is very common for lambs to be drenched around weaning, and then given another four or five drenches before their first winter. On farms where Nematodirus causes problems early on, lambs may even get drenched a month before weaning.
Another factor to consider is the presence and impact of tapeworm in lambs. Several New Zealand studies have shown that the effects of tapeworm on lamb growth rates are marginal or insignificant. Tapeworm may cause an increase in dag score, with an associated increase in the amount of time spent crutching. Lambs are born with a very small rumen but by the time a lamb is 5 weeks old the rumen is developing and it is starting to get a significant amount of nutrition from grass. This also means that the lambs are potentially exposed to parasite larvae on pasture.
Where covers are inadequate, ewes and lambs will be competing for feed and mum is always going to be better able to harvest the available feed. Infective worm larvae are concentrated in the bottom 2cm of the pasture sward; if this is where lambs are grazing, they are more likely to pick up worm burdens that will limit their production as the weeks go by.
Lambs from 6 months of age will generally have an immune system which is functioning well enough to control tapeworm, so tapeworm control is not normally needed after this point. The immune system will continue to develop over the following months to provide protection against other internal parasites, but this can take another 18 months.
If a pre-weaning drench is going to be used, care needs to be taken in the selection of the product. Abamectin is not routinely recommended in lambs under 16kg bodyweight as it has a narrower safety margin in these animals than other products. Donaghys Duell tape is a white/ clear combination drench with praziquantel added for effective tapeworm control and can be used in these younger groups of animals.
For lambs over 16kg, Donaghys TrivAL Tape is a triple active white/clear/mectin drench, again with added praziquantel for effective tapeworm control. If there is any history of drench resistance on the property it may be beneficial to use a triple acting product. Advice from an expert with knowledge of what is happening on your farm is highly recommended.
Now is also a good time to start thinking about the possibility of getting some information about the drench status of your property. It is highly recommended that a faecal egg count reduction test is carried out every 2–3 years on most farms. This is usually done in late summer, as this is the time that farms are likely to have enough lambs to run the test, as well as a good representation of the parasite species that may be causing issues. 
For further information, contact your Farmlands Technical Field Officer or the friendly team at your local Farmlands store.

Article supplied by Donaghys.