Increasing the density of animals on a piece of pasture changes grazing behavior, and is one tool graziers can use to meet certain vegetation goals. Here’s what Steve Freeman learned when he increased stock density, and what it’s good for and when it might not work as well.
Until July of 2007, those of us farming in the Ozarks had suffered through a two and a half year drought. July brought buckets of rain, and the pastures produced a tremendous growth of grass but also a wide mix of weeds (forbs) that come with a weakened sod. I had been reading about the management practice of ultra high stock density grazing (UHSD) and thought if ever I was going to try it, this was the time to jump in and give it a go.
An Initial UHSD Disbeliever
You, like me, may be hearing or reading about UHSD involving some herds being grazed at a density of one million pounds per acre! Not believing this was possible when I heard it, I sat down and did the math on the forage required to feed one million pounds of cattle per acre.
As a rule of thumb you can figure a cow needs to graze 2.5-3 percent of her bodyweight every day. So with one million pounds of dry cows, the grazing wedge per day would have to produce 25,000 pounds (2.5 percent of one million pounds) of forage per acre.
Since I know of no area in the country that produces this much forage per acre (equivalent to 25 large round bales per acre), I immediately thought I had heard a grazing tall-tale.
As can be the case when hearing of a new practice or idea, my entrenched beliefs were preventing me from seeing the potential of this new grazing method. I dug deeper and learned that the rancher using this grazing density moves the cattle as much as ten times per day.
Now do the math. One tenth (ten moves) of the 25,000 pounds of required forage is 2,500 pounds per acre, a very reasonable and attainable number. I also learned that this density is used only during the spring and summer growing seasons on very good sub-irrigated bottom land. While I didn’t plan to use this high of a stocking density, figuring out this example convinced me that trying out UHDG was possible on our farm.
Determining the grazing density for UHSD
I wanted to try out UHSD, but what is the number that tells a farmer when he has moved from intensive grazing to high density or ultra high density grazing?
I have been practicing what I consider intensive grazing for many years. This is a “graze half the grass, leave half the grass” system with a grazing density of 40,000-80,000 pounds per acre using one to two day moves. Without a specific number to guide me, I planned to roughly double our normal grazing density to make the transition to what I consider ultra high density grazing.
I had 140 bred cow/calf pairs and 99 acres of mature summer growth to work with. The cows weighed 1,100-1,150 pounds and the calves averaged 400 pounds at the time, giving me 210,000 total cattle pounds.
I estimated the grass/weed/forb pasture to be 5,000-6,000 pounds of forage per acre. The pasture was very thick and was a combination of fescue, orchard grass, crabgrass, red and ladino clover, white aster, chicory, ragweed, flea-bane and I’m sure a few other grasses and forbs.
Allowing for some stomping down of the grass and doubting that all the weeds would be eaten, I started off giving the cattle about 1.5 acres per day, moving once a day. This came to 140,000 pounds of cow per acre, per day. Here are some photos of a move:
To my surprise, the cattle seemed to relish everything in the pasture, except the older fescue. I was unhappy that some of the old stale fescue was not being grazed or torn up, so I increased the density to approximately 280,000 pounds per acre by moving them twice per day (but still consuming 1.5 acres daily). I did see better results in regards to the fescue and the cows were happy since they were now moving to new pasture twice a day.
Here are some other observations from my very limited (70 days) experience with ultra high density grazing:
• I was very pleased at how clean and even the fields looked after grazing. I don’t think there was a plant that was not eaten or trampled into the ground.
• Manure and urine distribution was very impressive.
• We saw more cow birds than ever before in the herd, which seemed to reduce the horn fly population. Coincidence or is this a benefit of UHSD?
• Younger and less aggressive animals in the herd did not do as well as they did under normal grazing conditions.
• I was surprised by how fast the paddocks came back after grazing. A virtual carpet of clover erupted on the grazed paddocks. In fact, I had planned to allow them three days of grazing before moving the back fence. But in little as two days the grass and clovers were growing back, so I had to move the back fence every day to prevent back grazing on the new shoots.
• I was initially worried about soil erosion. It was grazed right down to the soil in places, with lots of stalks and stems trampled in the ground. But after seeing how fast the forage grew back, I feel that soil erosion is not a problem. Remember that over grazing is almost always an element of how long a pasture is grazed, not how short the plant is grazed.
• A good water delivery system was necessary.
The Purpose of Ultra High Stock Density Grazing
It is to my understanding that UHSD is a tool to use for increasing organic matter and subsequently make your grass more productive. The cows are simply tools to use to reach this goal and I think dry cows are a perfect fit for this purpose.
If, however, your goal is to increase weaning weights or to grow stockers at a high rate of gain using UHDG, I would recommend that you begin cautiously. Like any management tool, it takes a while to learn to use it properly and small errors can lead to some pretty big wrecks when grazing at this density.
Using UHSD in the fall might become a common practice on our farm, since at this time of year, the breeding season is over and getting through winter without hay and improving our soil is more important than calf growth. Slowing down the rotation should allow us more grass for winter grazing and while I’m not sold on the practice, early results are promising. It will be very interesting to see how the paddocks respond during the next growing season.
This was a very short experiment, so take a look around for other graziers’ experiences with UHDG. You might also check out a blog about mob grazing written by Nathan Sanko. We can all learn from each others’ experiences, so do share in the comments below.
UPDATE: Since that fall, we have again used high density grazing the past two falls. We were fortunate to have one of the leaders of high density grazing, Greg Judy, visit our grazing system which was part of a farm day tour. Greg was very positive, educational and supportive of what we were doing and gave me some valuable ideas that helped me understand how to do a better job with high density grazing. The most important point Greg made was not forcing the cattle to graze the trampled forage or graze the sward too low. It’s difficult when you see all the forage lying there to not want to see the cattle do a little better job of cleaning it up, but I think this is where we saw some fall off in the younger or less aggressive animals. This has been our biggest concern with grazing this many cattle (370 head this past fall) in such confined areas.