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Managed Intensive Rotational Grazing for Sheep

Managed Intensive Rotational Grazing

Managed Intensive Rotational Grazing. That’s a mouthful. MIRG for short.

MIRG is a system of pasturing animals to maximize pasture growth. Proponents call it farming grass.

Two sheep grazing

Rotational grazing is nothing new. Dividing up a pasture into paddocks to prevent overgrazing goes back to the earliest agrarian societies. What is fairly recent is intensive rotational grazing. Instead of pasturing animals in a large paddock for a month or two, then moving them to the next paddock, MIRG is pasturing animals in very small paddocks for just a few days at a time, or in some cases hours.

The heart of the idea stems from giving pasture the optimum amount of time to re-grow before being grazed again. Short grazing periods stimulate growth, long grazing periods destroy pasture.

Colorado State University

Colorado State University

There are many benefits to the animals as well:

  • Animals are exposed to more varieties of forage because they cannot simply return to their favorite alfalfa patch every day
  • Animals are forced to move and exercise more
  • Fewer parasites build up in the soil and affect the animals
  • Manure is more evenly spread

Finally, perhaps the biggest benefit of all is soil health. MIRG and techniques like it build up far larger amounts of topsoil than any other known method. Rather than continually depleting the soil and subsidizing with chemical fertilizers, MIRG allows me to build healthier pastures that are self-sustaining.

Contrary to what it may seem, grazing is necessary to healthy pastures. If pastures are not grazed they turn into deserts. This was brought to my attention by the compelling TED talk by Allan Savory, a pioneer in the field of holistic land management.

Since acquiring our sheep last Summer I have had this nagging desire to figure out MIRG and apply it to our farm.

Tonight, I finally figured it out.

My first question was, can MIRG be used with a small scale of animals? We have 3 ewes and 1 ram currently, expecting lambs this Spring. The answer appears to be yes; I have found no literature saying there is a minimum amount of animals required. As long as the space requirements are met, the benefits of rotational grazing applies to 4 sheep just as much as 40,000.

My second question was, how do I size the paddocks for the number of sheep I have? The numbers are all over the map on this, and “stocking density” isn’t a terribly popular subject online. Thanks to a University of Minnesota Extension presentation, I was able to get some hard numbers and convert them for our farm.

The calculations use “Animal Units” or AU’s which are a livestock standard based on a mature 1,000 pound cow. The MIRG approach assumes 33 AUs per acre per day. So that’s 33 cows, or about 33,000 pounds. Keep in mind, this is dependent on the pasture productivity. It could be as low as 25 AUs or high as 80 AUs. But for the purposes of getting started, I am going with the 33 AU number.

My last question was, how big do I need to make the paddocks and how many of them do I need? If MIRG requires 33 cows per acre, that equates to 1,320 square feet per cow. Since our mature sheep are approximately 200 lbs, they will need 1/5th the space, or 264 sq ft.

The grazing periods should be as frequent as you can handle, no more than 5 days per paddock. Once per day seems to be a desirable number in most of the literature. But I have a day job, so I’m settling for twice per week. That means I will increase the spacing by 3.5, which is ~900 sq ft per sheep. Multiply by 4 sheep and we get to 3,600 square feet per paddock.

Square paddocks are recommended as opposed to rectangular or wedge-shaped which do not tend to get evenly grazed. So that means I’ll be making 60’x60′ paddocks (out of electric fencing) in addition to lanes for the sheep to follow to get to each paddock.

Drawing of paddocks for MIRG approach

Finally, I calculated out how many times I would have to move the sheep to allow the paddocks 30 days of rest between grazing. It’s 10.

To recap, modified MIRG for 4 sheep:

  • 33 Cows (AUs) / Acre = 165 Sheep / Acre (Using 0.2 AU)
  • 1,320 sq ft / cow = 264 sq ft / sheep
  • 3-4 day rotation = ~900 sq ft per animal
  • 4 sheep = 3,600 sq ft total
  • 3,600′ = 60’x60′ paddocks
  • Requires 10 paddocks to achieve 29-day rest period

This is subject to change depending on the number of lambs born this Spring, and the productivity of our pasture. The rule of thumb was to graze the animals when the grass reaches 9-inches and to move them when its down to 2″ or 3″.

Managed Intensive Rotational Grazing: Sheep enjoying pasture at sunset


  1. How did it go? This is about the numbers I am looking at. Thanks for the info and insight.

    Mark S

    • Hi Mark-

      Numbers are good. Fencing was not! :) Some of my braver sheep kept jumping through the electric fencing, so I ended up letting them free-graze by the end of the summer. Next season I will install better perimeter fencing and use combination of physical and electric fencing.

      I reviewed the numbers with both the author of the U of M presentation and a local shepherd. As with all things farming, “it depends”. Weather, grass variety, breeds can all have an impact on actual stocking density. Have to watch the actual plot. But the numbers above are fine for a starting point.

  2. Thanks so much for this article. I have 2 goats, and am getting 2 young sheep on loan this Spring in order to increase the soil health of my 8 tilled acres. I was feeling a little overwhelmed by the planning process, but you did it for me!

    • Thank you Judith! Best of luck to you. There’s no match to actual experience. But its a sound approach overall and I will stick with it this season again (after some fencing improvements).

      Nothing like animals to improve the soil health. If you really want to amp up your pasture in a short amount of time, put chickens on it, either following the livestock rotations or free ranging. They scratch and fertilize the ground better than anything.

  3. great article! I have 6 sheep and have been trying hard to figure this out and getting a lot of conflicting , confusing information. How many sheep do you have now and are you still practicing this?

    • Hi Lea-

      Yes, still practicing but again it comes down to fencing. We have 6 sheep currently. We have found the electric net fencing to be the most useful for sheep. They just run through the poly-wire strands. The other factor is the amount of work involved in moving fencing. Even 2X a week it becomes very labor intensive over the course of a summer. I ended up going with larger paddocks last year than originally planned because of the polywire failures. But then we had the problems of overgrazing–the sheep kept returning to the same plots rather than chow down on all the forage evenly.

      We are getting a new perimeter fence installed this summer, and it should make a big difference in the labor required, because we will only be moving electric fencing inside the perimeter. Will see how that goes!

  4. hi–curious about the pasture you’re using. Is it mostly all grass and forbs or do you have any tree crops? I’m wondering if with a super nutrient dense paddock I can get more sheep days out of a little less space. I’ll be running through tree lanes of almonds, hazelnuts, tree collards, and persimmons, as well as under plantings of comfrey and other nutrient dense herbs. the pasture itself is a mix of clover and various grasses. i have hoped to run a ewe and her 1-2 kids at around 250sqft per day in this system. any thoughts?

    • Yes, that is the idea: more productive pasture (at least in the long run). I am running the sheep between apple trees. The grass is a horse pasture mix.

      I think 250sqft/day would be more than enough. Nice think about electric fencing tho is that you can just change it if they need more/less space. Typically I have to mow sections after moving because they do not graze it evenly, which is a sign of too much space.

      Please drop another comment after you’ve tested it out and let us know how its going!

      • Hey guys thanks for the response! We close on the property this week, and my first move will be to get around 10k square feet established in grazing rows, with lanes of tree collards, persimmon, blueberries, pomegranate, hazelnut, and fig, and all of that underplanted with comfrey and lots of other goodies. I’ll definitely keep you posted as it develops. Thanks again for the response. Prayers for your family for a bountiful harvest this year! Peace

  5. Rory, thank you for organizing your knowledge. My question would be what sort of hard fence you are using around the perimeter. Do you have gates between paddocks? What size are the gates to allow for safe movement between. Do you have water, feed and shelter in each paddock or do you rotate those needs with the animals? Thank you for your time and help!

    • Hi Riley-

      We just had a perimeter fence installed (formerly were using polywire electric for each paddock, but didn’t work well). The perimeter fence is 6″ woven wire, and stands 48″ high. We can easily create custom paddocks with electric fence inside of this perimeter fence now. So we do not have gates, but just move the sheep inside of electric fences after they are set up in the new area. If you are installing permanent gates, they do not need to be more than a few feet wide. Unless you have hundreds of sheep, they will tend to follow each other single-file and can easily pass through a 1-2ft opening. Where we do have gates they are 3ft.

      We always keep fresh water in the paddock (5 gal buckets), but do not provide feed as they are pasture-raised. Occasionally we will give them some corn, but not every day. They are ruminants and do not need corn unless you are trying to fatten them up faster than nature intends (unless lambing of course). We also keep a salt lick or loose mineral salts available to them. There is no shelter on the pasture, just some orchard trees for shade. They stay outside during the rain and it doesn’t seem to bother them like it does goats.

      If you have other questions please ask, I don’t want to ramble on too long here.

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