Already this year I’ve had a couple of cases of flystrike in lambs but none in ewes. It’s time to take preventative steps.

Now the confusion starts.

I want to use a convenient pour-on product that is effective and gives a long period of protection. This especially applies to ewes that will be carried through to next season. CliK, which claims up to 16 weeks protection, will be my choice for this group.

But for ewes earmarked for early culling and for lambs being selected every other week for slaughter, the priority is to use a flystrike product with a short withdrawal period. CliK with its 40 day meat withdrawal is not suitable. The newer Novartis product ClikZin comes with a 7 day meat withdrawal and about 6 weeks cover. The downside is that the cost per sheep with ClikZin (over €1.50 per head) is almost as high as it is for CliK even though you are applying only about one third of the active ingredient.

The other pour-on option, and the one I used last year, is Vector. Vector comes with an 8-day meat withdrawal plus a claim for about 8 weeks protection. Whereas CliK does nothing for maggots already hatched on a sheep, Vector claims some control of these plus a control of ticks and lice which can be important for some. Again this is a Novartis product but the same formulation is marketed by Bimeda and Osmonds as Ectofly and Ovisect.

Some farmers still like to use plunge dips. The attraction is that they get cover of all skin parasites, lice, keds, ticks, even the dreaded sheep scab. Maggots already hatched, will be killed. The downside is the long meat withdrawal (35 days) and poor enough flystrike protection. Also you have the labour of dipping and the threat to the health of the operator.

A decade ago few of us would have been even conscious of withdrawal periods. Now with ever more sensitive testing for residues and the importance of Quality Assurance, withdrawal periods for animal treatments and medicines are really impacting on day to day farming.

Also, as tests for residues become ever more sensitive, the withdrawal periods become ever longer.

Just look at the meat withdrawal times for some widely used medicines:

  • Cydectin 10% LA injection for cattle – 108 days
  • Cydectin 2% LA injection for sheep – 104 days
  • Such products have wonderful long term activity against parasites but you must be careful not to use them in animals approaching the slaughter stage.

    Authorities are particularly concerned about residues of fluke medicines appearing in meat. The widely used Trodax has a 60 days withdrawal for meat. Flukiver injection has 77 days. 60 days for Ridafluke. Zanil, which is the main product used against the new threat of rumen fluke, has a 28 days withdrawal period for meat and 3 days for milk. CTC antibiotic powder used to control pneumonia in cattle, has a 35 days withdrawal period. Some of the newer antibiotics can be up to 40 days.

    Who said that sheep farming was a simple relaxed way of life?