Flock Health – The Foundation for Sheep Performance

Wednesday, 11 July, 2018

Output on flock health is one of the biggest variable costs on sheep farms across Northern Ireland. Controlling parasites and lameness are among the two largest within the flock health calendar. Many drugs are not working on farms but there are still many farmers that are unaware of what ones they are. You must identify what drugs are effective, have an effective control strategy and only treat when necessary. When treating animals it is key that the correct amount is given and in the correct manor. There has been some sheep slaughtered and sent for post-mortem that have damage to their throats or muscle areas. Not has this been ineffective but in slaughtered animals, this can be a valuable loss to the food chain. Research in the UK has found resistance to widespread macrocyclic lactone (Iver-mectin, Moxidectin and Doramectin) resistance sheep scab mites. Key advice to work closely with your vet to establish what method will work on your farm. Poorly applied pour-on products will be ineffective and will build up resistance within the flock so care should be taken when used. In relation to wormers, there are five families or classes of drugs. (Benzimidazole (white), Levamisole (yellow) Macrocyclic Lactone (clear), Amino Acetonitrile Derivatives (orange), Spiroindoles (Purple) . Resistance is extremely high in white and clear wormers so should be used with caution. When farmers ask for advice they should know what colour of drug they previously used and should try to rotate if possible. Combination drugs (flukicide & wormer) are very convenient on many sheep farms as it can cover a wide range of parasites. Again should be carefully used and to the right amount.

Lameness is another issue on some sheep flocks. Key advice is to establish what level is within the flock. Identify the cause of the lameness by discussing with your vet or advisor. Treat the infection where possible. Put a procedure in place on the farm of handling these sheep and cull persistently lame sheep. Antimicrobial resistance is an issue that many farmers have been working to reduce. Routine hoof paring will increase the level of lameness within the flock and quarantine procedures should be implemented to prevent purchased sheep passing infection to the existing flock.

Sheep farmers should be vigilant with emerging sheep diseases. OPA (Ovine Pulmonary Adenocarcinoma) is an infectious fatal lung disease. Early detection and culling are key to reducing the levels within your flock if it has the disease. Recently developed methods like ultra-scanning for OPA is one option to establish or you can send any dead sheep for post-mortem.

Millions of pounds each year is spent on vaccination for the prevention of diseases. There are a wide range of vaccines from live vaccines that are given intramuscularly, scarification vaccines, which are applied via a scratch on the skin to, inactivated vaccines which are given subcutaneously. Storage, site of administration, vaccination equipment and timing are key to having the most effective results. Gaining an understanding of how each of the vaccines works is key. Boosters are required with many vaccines at first and if not applied will have been a waste of time, money and effort.