Internal parasites of sheep, goats and young dairy cattle can be a challenge for both organic and non-organic farms.   In the absence of chemical controls, keeping organic animals healthy and productive during the grazing season requires a good understanding of parasite-host  interactions, grazing management strategies and animal selection.  Worms and coccidia and other organisms are developing resistance to multiple chemicals so even if you are not organic it is advised that you start looking at alternatives to routine de-worming.  Dr. Ann Wells presented some very useful and practical information on parasite control and prevention systems in April at two days of NOFA VT workshops.   You can get a copy of one of her recent articles from the NOFA Dairy and livestock technical assistance website, and you can contact Sarah if you’d like a copy of the notes taken at Dr Wells workshops.

Dr Wells has not found any alternative treatment which works as well as the pharmaceutical treatments, so management and prevention is essential.  Currently Ivermectin is the only pharmaceutical dewormer that is allowed in organic production.  It can NOT be used in slaughter stock and it requires a 90 day milk withholding for diary animals.  It is also damaging to the dung beetle populations on farms where it is used.

Here are just a few key points to consider in developing a parasite prevention plan for your goats, sheep or cattle:

  • Selection:  Keep replacement animals from dams and sires that don’t have parasite problems or/and who don’t shed as many eggs in their manure.
  • Nutrition: Provide good nutrition including a mineral mix to animals.  This is particularly important for animals which are most susceptible (young stock and small ruminants).
  • Grazing management is an essential part of prevention.
  • Since most of the infective larvae are in the bottom 2 inches of the pasture, manage to leave a 2 to 4 inch residual behind to minimize parasite infection.
  • Rotate pastures:  this improves the nutrition going into the animals, it improves the pastures, it can prevent them from grazing too short if done correctly
  • Stock density is important.   Lower density = fewer problems
  • Grazing with multiple species can be helpful.  Goats will graze around cattle manure and cows will graze around goat manure and they are a dead-end host for each others parasites. For sheep they have found that never grazing sheep after sheep in a pasture makes a big improvement.  Dr Wells grazes cattle after the sheep in the rotation.
  • Diversity of plant species in the pasture can be a useful part of parasite management system.  This will provide more minerals as well as some medicinal components to the animals.
  • Consider planting some high tannin forages.  These include plants such as birdsfoot trefoil, yellow dock, curly dock, and chicory.  Dr Wells is doing some research on grazing chicory as part of the parasite prevention strategy for sheep and is seeing some preliminary success.

Some of the research which Dr Wells has done on alternative treatment materials includes: