The Benefits of Good Worm Control

As protein demand increases worldwide, efficiency in production is crucial to meet this challenge. Internal parasites are the greatest cause of lost production in grazed ruminants, so their management and control are vital to enable sustainable production from pasture.


Stomach worms in lambs are the major production limiting parasites in UK grazing systems, they cause reduced carcase quality, weight loss, delayed finishing and decreased wool production. Gut worms result in reduced weight gains (up to 47%) and reduced wool growth (up to 21%)1. Good control of worms can result in up to 4.7kg extra live weight during the grazing season2. Higher lamb DLWG means faster finishing and maximises the potential of feed input.


Good worm control is a balance between the level of challenge that would reduce productivity and the level required to enable the development of protective immunity. Low levels of infective larval challenge have minor effects on growth rates but allow for the development of immunity. Larger challenges check growth and animals will not catch up to the cumulative growth rates that they would have achieved had the challenge been small. It is important to assess and reduce pasture risk – graze lower risk pastures such as hay and silage aftermaths or use mature ewes to ‘hoover’ larvae off infective pasture to keep larval exposure low.


It is important that anthelmintics are only used when necessary to prevent the overuse of these products, with the added benefit of reducing the cost of treatment over the season. There are big variations in weather conditions and worm challenge across different seasons, so it is important not to dose based on the calendar. Growth rates and faecal egg counts can be used to assess whether treatment is needed. When treatments are required it is important that the correct dose is given for the weight of the animal.


CYDECTIN 0.1% Oral Solution for Sheep has a long dosing interval of 8 weeks with a meat withhold of 14 days. This allows it to be used strategically to control worm burdens in lambs. Having a long dosing interval gives many advantages such as a reducing workload and decreasing the number of doses needed, which in turn can lead to less stress on the lambs, improved growth rates and lower input costs.


There are many options for worm control and in order to have an effective strategy it is important that a farm parasite control plan has been created in conjunction with your animal health provider.


1. Charlier, J. et al 2014: Trends in Parasitology, Vol. 30, No. 7

2. Miller et al Veterinary Parasitology doi:10.1016/j.vetpar2011.11.063


CYDECTIN® 0.1% W/V Oral Solution for Sheep contains moxidectin. POM-VPS. For further information please see the product SPC, or contact your veterinary surgeon, SQP or Zoetis UK Limited, First floor, Birchwood Building, Springfield Drive, Leatherhead KT22 7LP. Customer Support 0845 3008034. www.zoetis.co.uk. Always seek the advice of your medicines provider. Use medicines responsibly (www.noah.co.uk/responsible). MM-13951. Prepared April 2021

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