Keeping organic sheep

Sheep fit well into many farm operations.  If self-sufficiency and sustainability are your goals, raising sheep has many advantages.

Sheep do well in forage-based systems, are less dependent on harvested grains and require the lowest percent of fossil fuel usage compared to other livestock operations.  They require minimal shelter even in cold climates and they integrate well with other livestock.

If your goal is to produce a consistent supply of certified organic lamb, it is not so easy.  For many organic farmers the most difficult aspect of raising sheep organically is the control of internal parasites.  Sheep are particularly susceptible as they graze close to the ground and regular use of chemical wormers is the norm throughout the sheep industry.

Both large and small scale producers have found eliminating the use of parasiticides to be their biggest challenge.  Advice is often contradictory and clearly there is no easy answer.

Organic certification standards allow worming of ewes with conventional products (only Ivermectin in the US) when preventive management fails to prevent infestation, but not during lactation or in the third trimester of gestation.

A 1998 paper by OMRI, discussing the National Organic Standards Board (NOSB) recommendations for livestock production, supports the position that all parasiticides should be prohibited for slaughter stock.  But it also acknowledges that special consideration may have to be given to breeding stock and fibre-producing animals.

In Britain the Soil Association Standards allow for the restricted use of anthelmintics (dewormers) for all ewes at lambing when resistance to parasites is low, if they are showing signs of an unacceptable worm load.  They also allow therapeutic treatment of ewes and lambs at other times.  However, reliance on these substances is not recommended and producers must implement a management system that aims at keeping worm populations at low levels.  Ivermectin-based products are prohibited.

Producers in British Columbia would like to see similar provisions in North American standards in order to safeguard animal welfare.  They claim a strategic worming at lambing would control subsequent infections in lambs and be much more effective than worming ewes at other times.

Organic producers in New Zealand have developed some successful strategies for keeping worm populations low  (outlined in Chapter 2.2 of the Organic Livestock Handbook).  Producers in Canada report varying degrees of success and many remain skeptical about the feasibility of organic production for large flocks.

Janet Allen of Dragon Mountain Farm in Quesnel, British Columbia has a 200 ewe flock but, unable to keep worm populations down, she withdrew them from the COABC organic certification program.  In 1998 she carried out a research project to investigate the effects of using alternative wormers.

Garlic, diatomaceous earth, pyrethrum and Hoeggars Herbal Wormer were tested on groups of weaned lambs.  These lambs were pastured on second-crop grass, clover and alfalfa and moved weekly.  The study failed to show any positive results in terms of reducing parasite populations.

Other producers report diatomaceous earth helps keep ewes healthy but is ineffective with infestations in lambs and some claim positive results with Hoeggars Herbal Wormer, chopped carrots, garlic and pumpkin seeds.  There are, however, no documented studies of sheep flocks that demonstrate the effectiveness of these natural wormers.


Strategies for internal parasite control

In flocks with high parasite loads alternative wormers and rotational grazing do not appear to provide adequate control.  A multi-faceted approach and a large enough land base (or small enough flock) offers more promise.

Based on research from Scotland and New Zealand and the observations of producers in North America, a strategic approach needs to involve all of the following:

  1. Breeding for resistance.
  2. Good nutrition and minimal stress.
  3. Use of high protein pastures containing plants high in tannins — Birdsfoot Trefoil is highly recommended and does not cause bloat.  Tannins help control stomach worms (Ostertagia) but have little effect on intestinal worms (e.g. Nemotodirus).
  4. Regular use of ‘preventative’ wormers such as garlic, conifer boughs, herbal wormers or homeopathic remedies (Kamala 3x) to keep populations low.
  5. Timing lambing to avoid exposing lambs to high levels of infectious larvae.
  6. Moving lambs to clean pasture at five to six weeks or when they start to consume herbage — they do not pick up significant levels of infection before then.
  7. Preventing grazing of contaminated pasture by lambs younger than eight months, i.e. before they develop immunity.
  8. Avoiding grazing lambs on the same pastures in consecutive years.
  9. Mixed or rotational grazing with other species such as cattle.  Recommended is a stocking ratio of six sheep to four cows.  Following sheep with cattle or horses is considered the best option.
  10. Post-lambing worming of ewes before going onto clean or safe pasture.  If synthetic wormers during lactation are not allowed by the certification agency, a natural alternative may help.

Additional tools to help overcome parasite problems might be available in the future.  For example, a lungworm vaccine has been developed in Britain and biological control of parasite larvae in the field is being investigated.

Clean grazing

For many farmers the biggest obstacle is providing clean pasture.  To be considered completely clean, sheep should not have grazed on the land during the previous for 12–14 months.

The severe winters in Canada are often assumed to reduce overwintering populations but it is not enough; the brown stomach worm Ostertagia is particularly hardy.  Overwintered populations will decline to low levels by the end of June if no spring grazing occurs.

Integrating grazing with forage and arable crops is helpful.  Sheep can be moved onto hayfields, and brassicas seeded into stubble can be used to extend the grazing season and to provide clean pasture.

Turnips can be grazed into the winter months if there is minimal snow cover and no ice.  Clean grazing can also be provided by alternating sheep and cattle on an annual basis.

There are additional strategies to consider if using MIG techniques for pasture management.  Provide water and shade in paddocks rather than having sheep return to a common area where reinfection can occur.  Move sheep before pasture gets low so they do not ingest larvae, then use cattle to graze it down to expose larvae to sunlight.

Note that this is a reversal of the usual recommendation to follow cattle with sheep because they prefer the shorter grass — optimal grazing is at 10–15 cm (4”–6”) rather than 15–25 cm (6”–10”) for cattle.  Swampy areas should not be grazed if liver fluke is a concern.


Breeding for resistance

A gene has been identified in Scottish Blackface sheep which dramatically reduces the number of eggs laid by individual worms.  This shows that resistance can be hereditary and that selective breeding could be an effective strategy to improve resistance and productivity.

A breeding program should select lambs that develop an effective immune response during their first growing season.  The lamb’s ability to control the development and egg-laying ability of ingested larvae will determine whether an infection will be ineffective or cause serious symptoms.  It also influences the number of eggs spread in the faeces and subsequent contamination of pastures.

At times of parasite challenge, identify lambs with low faecal egg counts — this is highly correlated with increased growth rates.  Results are obtained more quickly with intensive selection i.e. using the top 10%, and with large population sizes because there are more animals to choose from.

Use of resistant sires is especially effective.  Offspring of susceptible sires can have 40 times more eggs in their faeces than offspring of resistant sires.

The presence of resistant lambs will also help susceptible grazing companions in the same way as mixed-species grazing reduces pasture contamination.



Good husbandry, aimed at prevention of problems, is the key approach for organic production.

Sheep kept outside on pasture in winter with open sheds or trees for protection from the elements are often healthier than sheep kept in closed barns.

With good nutrition many breeds can tolerate cold dry weather but choice of breed is important for climates that are cold and wet.  A fleece that sheds water and dries quickly is preferable and black hooves tolerate wet conditions better than white ones.

Make sure sheep get exercise by feeding outside in winter unless there is heavy snow or freezing rain.  Good quality hay is essential — one recommendation is to cut early and if spoiled by wet weather take it out of the windrow and let it decay in the field.  The regrowth of the early cut hay is leafy and nutritious and can be cut when the weather is more favourable in midsummer.

Also beneficial are pastures containing a good diversity of herb species, as is supplementary feeding of kelpmeal to ensure that vitamin and mineral requirements are met.

Internal parasites are usually suspected if animals fail to thrive but should not be assumed without doing a faecal analysis.  Note that false results can be obtained from infected lambs in the first few weeks of the grazing season.

Quarantining and faecal sampling for any incoming stock are good precautionary measures.  Recommendations for other ailments common in sheep are given below:



This is preventable.  Always check and quarantine new additions to a flock to prevent contamination of pasture.

If footrot occurs rest pastures for two weeks to kill the infectious agent Bacteriodes nodosum, which does not survive in soil for more than a few days.

Treat infected animals as necessary with homeopathic remedies (Silica 200 daily for 10 days or Hepar sulph 30 twice daily for five days when pus is present) or copper sulphate (zinc sulphate is not listed in permitted materials lists for livestock).  Cull any chronic carriers.


External parasites:

Shearing before lambing helps break the life cycle of lice and keds as well as providing easy access to a clean udder for lambs.  If there is a serious problem, restricted use of botanical pesticides may be allowed by the certification agency.


Lambing difficulties:

Aim for a trouble-free flock, culling ewes that require assistance at lambing.  Select ewes with good mothering ability and avoid overfeeding of pregnant ewes carrying single lambs.


Lamb mortalities:

Hypothermia and starvation are the most common causes of preweaning mortality.  Statistics show losses are higher with winter lambing.  On pastures forced movement of newborn lambs should be avoided to prevent mismothering — ewes with new lambs should be allowed to gradually drift into new paddocks to rejoin the flock.

Prolonged periods (24–48 hrs.) of wind, rain and cold (5°C, 40°F) will increase mortality in lambs 3–5 days old.  Producers have found that the Bach flower “Rescue Remedy” works well to revive slow lambs.



Flocks develop immunity.  If you have never had the problem beware of introducing sheep from flocks that are carriers.  The homeopathic remedy Rhus tox 12 is used for treatment when crusty oozing lesions are present.


Use of homeopathy in sheep:

The book Homeopathy, The Shepherd’s Guide provides useful information for those willing to try homeopathic remedies.

Producers in Britain have had success with using nosode remedies for complaints such as orf, footrot, coccidia, mastitis and abortion.  Unfortunately these cannot be purchased in Canada.

Homeopathic remedies are most useful at lambing when handling ewes and lambs individually.  If treating a flock as a preventative measure, remedies can be administered via the water trough.

Studies in Britain show that homeopathy is more effective at preventing pasteurella pneumonia than vaccination.



Coyotes, dogs and occasionally bears cause the most problems.  Good electric fencing (train sheep when recently shorn) or the presence of guard dogs works well.  Llamas or donkeys are also used as guard animals but reports as to their effectiveness vary.

This text is extracted from COG’s Organic Livestock Handbook.  The book goes on to discuss dairy sheep, timing of lambing, and the most important features of a sheep operation.

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This project has been made possible in part by the Government of Canada.

This project has been made possible in part by the Government of Canada.

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