Staying vigilant for signs of liver fluke and worms is paramount for sheep farmers, as the risk of parasites remains hugely variable in the run up to spring.
Matt Colston, ruminant technical consultant at Elanco, says traditional risk periods for parasites are no longer applicable and regular monitoring is the only way to know if – and when – treatment is required.
“An example of this variability can be seen with liver fluke,” he explained.
“Deaths caused by acute fluke infection were seen well into January this year, and historically we’d expect these to happen in late autumn and early winter.”
He said peak periods for parasite infection have varied so much in the past five years that a ‘typical year’ no longer exists, and doing testing on your own farm is the only way to know what is going on with parasites.
For liver fluke, Mr Colston said it is possible to find out if, or when, the infectious stage has appeared on a pasture by using some of this season’s lambs as sentinels and checking blood samples at intervals throughout the season.
“Once the sentinel lambs have shown fluke is active with a positive antibody result, follow-up dung samples can be used to show what stages of the parasite are present,” he explained.
A coproantigen test will pick up fluke at the late immature, ‘teenager’ stage, while an egg detection test will show when fluke have reached the adult stage, which is 10-12 weeks after infection.
“Using the right test at the right time in the right animals is necessary to get a true picture of what’s happening on the farm so it’s worthwhile speaking to your vet to get the right testing plan for your farm,” added Mr Colston.
“By knowing what stage the fluke are at, the appropriate active can be chosen to ensure a good kill rate when treating your flock.”
For worms, Mr Colston said the cold snap in January is likely to have reduced the number of worm larvae active on pastures, however, it is worth testing mob samples to see if any groups of ewes might benefit from treatment.
“Farmers were previously advised to treat the whole flock at lambing, to reduce the worm challenge for lambs in the following grazing season, however, we now know we can have the same impact by targeting ewes that might be struggling to maintain body condition up to and around lambing,” added Mr Colston.
“Thin ewes, older ewes, those carrying injuries or any other illness, and those with multiple lambs would fall into this group.”
Lastly, Mr Colston said ectoparasites – in particular, sheep scab – can cause serious problems for a flock if not identified and dealt with effectively before lambing time.
“If any sheep are even slightly itchy when gathered for scanning, this offers the opportunity to blood test a set number for scab antibodies, to either rule out or confirm the need for further action,” he added.
“Plunge dipping in an organophosphate (OP) is the only treatment option likely to be fully effective, and modern dipping waggons mean even pregnant ewes can be effectively treated without causing undue stress.”
For more like this, sign up for the FREE South East Farmer e-newsletter here and receive all the latest farming news, reviews and insight straight to your inbox.
