Here are the ins and outs and the math for figuring out how big each strip should be to feed your cattle and make best use of your stockpile. It comes to us from our November 2014 issue of On Pasture.
We reconfigured our farm’s permanent, hi-tensile fence to better allow the use of portable fencing. Portable fencing allows flexibility, and flexibility allows the management of your grass to be done much better and more easily. (Read more about that here.)
The difference between strip grazing and just making small paddocks is the lack of a back fence. Strip grazing is done when the forages are dormant, and the cattle are allowed to go back over what they have grazed. If done when the forages are growing, the livestock would begin grazing the re-growth and do damage to the plants.
Grazing stockpiled forage during the dormant season is fairly simple. You will need two portable reels and enough temporary posts to hold the wire up. If you don’t have the perimeters of your paddocks powered, you can use a small portable energizer to power the polybraid. What you need to learn to strip graze properly is how to judge the amount of forage per acre that is stockpiled, plus how many pounds of grass your stock need to eat every day. This varies greatly depending on whether you’re grazing stockers, dry cows or lactating cattle. As a rule of thumb, I use 3% of the cows’ body-weight to determine her daily needs. This may be too much for a fat dry cow, but may not be enough for a lactating fall calver. But all of this will be a guess to start with and adjustments can be made as the days go on. We baled hay for many years and even did custom haying for awhile, so to keep it simple I decide about how many bales of hay per acre the stockpiled grass would make and use this to determine how much grass to allot for the grazing period. All of the numbers and calculations you need are in Management-intensive Grazing: The Grassroots of Grass Farming, Jim Gerrish’s book on MiG grazing, but I will give you my ballpark method of determining how much grass to allot cattle for the grazing period.
Let’s assume this is an every day move, the most efficient way since 85% of the grass will be utilized. With a three day move, figure on 55-60% of the grass being utilized. Let’s also assume we have 100 dry cows that weigh 1000# each. We will figure they need 3% of their body weight, which means we need to give the cows 3000 lbs. of stockpiled grass a day. Using cowboy arithmetic, we estimate that the stockpiled grass, if we were to mow, rake and bale it, would make three 1000# round bales per acre. Trying to keep this simple, we will say the field is 880 feet wide.
100-1000# cows = 100,000#
3% of 100,000 = 3000# (forage needed)
Stockpile is estimated at 3000#ac (three 1000# round bales)
Therefore, we need 1 acre of grass to feed the cows for one day.
1 acre = 44,000 sq ft (rounded up)
44,000 divided by 880′ (width of field) = 50 ft.
How do we know where to put our first portable fence? First, we need to establish what the water supply will be, and we will begin grazing from that point. So, in our example above, our first portable fence would be fifty feet from the end fence nearest the water. But wait, we started this off by saying that with a one day move we would get 85% utilization, so the rest is being trampled or manured on. Correct, but also we had dry cows, who actually could get away with eating 2.5% of their body-weight. So the first day, we’ll keep it simple and set up the first fence fifty feet from the end. If we find the cows are leaving quite a bit of grass, we will shorten the distance up a small amount. If they seem unhappy and the rumens look shrunken the next day, we’ll give them a bit more with the next move. This is not an exact science, but a learned skill and you need to keep your eyes open and learn to really read your cows and your grass. Your cows also need to learn the system. When the cows become accustomed to strip grazing they learn to eat quickly. But when first being introduced to strip grazing, cows will often walk around the strip picking at the grass and walking the boundaries. So, the first couple of days the cows might be a little hungry, because they pick the good green grass and walk on the rest. They soon learn that this is all they are going to get to eat and their grazing habits change. They learn to eat fast and to quit picking.
Day 2–Our dry cows look good the next day, and the dormant grass has been grazed evenly down to 3-4″. We then take our second reel and set of posts and give them the same 1 acre (50ft x 880ft) as the day before. Now, we almost always do the next day’s set-up the day before so that we are ready to move the cows when we arrive at the field. We find if we wait to do it the day of the move, the cows will often walk the portable wire fence line following you up and down as the wire is being rolled out and the posts stepped in. But when you first begin strip grazing and are unsure of your skill at deciding the proper amount of grass to allocate, it can be easier to wait and see how your previous day’s section of grass looks before making the next section. After awhile, it becomes second nature and measuring doesn’t need to be done every day.
Back to the move. After the second wire is up and hot, you have several choices as to how to let the cattle into the next strip. We’ve tried quite a few methods, and have had quite a few messes to deal with. The way we now allow the cattle in, is to start rolling up the portable wire while it is still hot. The cows know they can begin falling in behind and moving around you through the ever growing gate you’re making, and if any decide to try a shortcut and go through or over the wire, it can be pulled taut and they will receive a good shock. After so many years of being moved, our cows have all of this down, and rarely do we have any problems with the moves. People often ask me, “how do you get the cattle to move?” Believe me, after a few moves the worry becomes, “while the cows move, how do I get out of the way!” They learn very quickly that there is fresh grass to be had.
We space our portable posts 60-100 ft apart. Remember though, our cattle are very accustomed to portable fencing and we see almost no testing of the fence. If your cattle are new to this, it may pay dividends to shorten the distance between posts and make sure the wire is the correct height (nose level) over the entire distance. Also, make sure you have plenty of voltage in the wire.
Remember the different nutrient needs of your animals. Lactating cattle and stockers have much higher nutrient needs than dry, pregnant beef cows. You can increase the nutritional level of the stockpiled grass by leaving a higher residual level. This way, you allow the stock to graze more of the green grass without having to eat as much of the dry, dead leaves. Their manure will give you a good idea of the nutrient level of your grass. If it’s the consistency of pancake batter or even looser, you know the nutrient level of your grass is fairly good. If it starts stacking like mounds of Play-dough, you need to either allocate more grass or begin supplementing protein.
Using stockpiled fescue to winter our stock has been one of the best cost cutting moves we’ve made. Large and small operators can both benefit from the practice. It takes the same amount of time to move 200 cows as it does 20. The only difference is the size of the section of grass you allow them. Unless the fields are extremely wide, most moves can be accomplished (with the next days’ fence put back up), within thirty minutes. For the most part it’s an enjoyable job, and it gives you a real chance to see your cattle. Some days, when it’s 35 degrees and raining, the cab of a tractor seems very inviting, but all in all, it’s a good job. If you remember you could be making as much as $200 an hour in saved expenses during that thirty minute walk, it can be quite satisfying!
(This is a brief overview of how to use stockpiled forages. For a more complete explanation of this practice, please read Jim Gerrish’s book, Management-intensive Grazing: The Grassroots of Grass Farming.)