Medicated grit is increasingly being adopted in the fight against the cyclical affects of strongylosis on red grouse populations following research by the Trust which suggested that medicated grit can dramatically reduce worm burdens. Users of medicated grit are, however, reminded of the legal requirement to withdraw the drug a minimum of 28 days before shooting, and for it to remain inaccessible to the grouse though-out the shooting season. Good practice (using double sided grit boxes or other means of withdrawing it from use) is essential to ensure that medicated grit remains a tool for controlling strongyle worm in grouse.
Medicated grit uses an anthelmintic and so the withdrawal period is required to ensure that the drug does not reach the human food chain. Unless the withdrawal requirement is closely followed there is a danger of residues remaining in birds and the likelihood of a challenge to this important method of controlling strongylosis.
Strongylosis is caused by a parasitic threadworm, Trichostrongylus tenuis, which lives in the guts of the red grouse and at high levels can cause significant reductions in both breeding success and direct mortality. Adopting medicated grit to control this disease is not a simple process and requires investment in time and money and correct application. If you have not adopted a gritting regime before then you need to establish a suitable grit grid, allowing approximately one gritting station per pair, and remove alternative sources of grit. Ensure that you make available both medicated and normal grit so that the grouse become accustomed to obtaining their grit needs from your carefully planned grid.
Using double sided grit boxes with a flip lid is a good way of supplying the grit as importantly it makes it easy to “swap” from medicated to untreated grit before the shooting season. For further guidance on the use of medicated grit please contact Grouse Technical Services on 01325 717930.