The Grovestead

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.

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.

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.

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″.

The story of our getting sheep started with a hunt for hay baling equipment. Every year we lose one-third to one-half of our hay crop to delays. We rely on a neighboring farmer to cut and bale our hay, and being one of the smallest acreages on their list, we often miss the best weather for cutting and drying. Needless to say, this has been a source of much aggravation each Spring.

Every year as the farmer comes to chop and haul away the wet, rotting hay I resolve once more get my own baling equipment and start making my own hay. Just a few problems. Baling implements are expensive and my tractor isn’t powerful enough to run them. By the time I’d finished making all the upgrades I’d be $15,000 in the hole. That’s a lot of debt for 3 acres of hay.

So I did what I always do when faced with an unsolvable problem. I prayed about it. The Lord told me I hadn’t done enough research. There were creative alternatives I hadn’t considered yet. That’s when the hints about sheep started appearing. “Little Lambs” started appearing everywhere, starting with Harriet’s shower gifts. She received three lamb stuffed animals from three different people. Then a friend asked if I would consider raising sheep this year because he wanted to buy locally grown lamb. I finally got it.  The creative alternative: Don’t bring the hay to the animals, bring the animals to the hay.

The sheep have been wonderful to keep. They baaa incessantly every time I enter the barn to let them out or shut them up. Although its more of a maaa, as in “maaa! give me more hay!”

They are more skittish than the goats, who are as friendly as dogs. But they are getting more tame over time. Their propensity to waddle through cockleburs, those velcro-like seed pods that stick to everything, means we won’t be getting much usable wool out of them.

It has taken most of the summer, training the sheep into various fencing configurations, but I finally was able to fence them into the alfalfa field surrounding my apple trees, which are planted in the corner of our hay field. Its the perfect setup. The sheep get fed mowing the grass around my trees. It had to be sheep, because goats or cows would certainly eat the trees as well!