Some factory agents have highlighted the importance of adhering to meat withdrawal periods when sending lambs for slaughter.

This is particularly relevant when treating heavier lambs for worms, as these lambs may come fit for slaughter within the product’s meat withdrawal period.

If traces of anthelmintic (wormer) ingredients are detected – by Department of Agriculture (DAFM) factory inspectors – the meat from these animals will not enter the food chain.

In addition, the farmer will be at a loss of the stock and could receive penalties in the form of a substantial deduction to their basic payment.

Therefore, when treating lambs for parasites, it is important to use the product appropriately – according to manufacturer’s instructions – and adhere to its meat withdrawal dates.

Unsurprisingly, the withdrawal dates differ for each anthelmintic product licensed for use in sheep in the Republic of Ireland.

Withdrawal periods

The Benzimidazoles (white group) class of anthelmintics have a relatively short withdrawal period – depending on the product – ranging from four to 28 days.

The Levamisole (yellow group) class of anthelmintics generally have – on average – a longer withdrawal period compared to the white drenches. Depending on the product, the withdrawal period for yellow wormers range from 14 to 21 days.

From all listed products licensed for the control of worms in sheep in the Republic of Ireland, the Macrocyclic Lactone (clear group) class – on average – has the longest withdrawal period of 35 days and ranges from two to 104 days.

Some products that include the Moxidectin active ingredient can have up to a 104 day meat withdrawal period. In addition, Ivermectin-based products can have a meat withdrawal of 10 to 42 days.

Turning to the flukicides – licensed for sheep in Republic of Ireland – the meat withdrawal dates for these products range from four to 77 days. Some active ingredients are: Closantel; Triclabendazole; Rafoxanide; and Nitroxynil and these have the highest meat withdrawal period ranging from 42 to 77 days.