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Newsletter of Penn Dutch Cow Care April 2012

Hi Folks,

It looks like it’s an early grazing year, at least earlier than average. I’d like to cover the grazing topic one time real well before the new season gets going, since I’m passionate about good grazing and seeing pasture land used efficiently and profitably..

How do we know how much green, growing mass of edible plants are there for the animals once they arrive in a pasture field? Is there as much as you think? Or might there actually be more? Or possibly less than you thought? How will you really know? The question is this: are you providing the right amount of pasture space to match what the paper ration says that they are eating in pasture? Are you possibly giving them more space than what is needed – and therefore cheating yourself out of important pasture intake? Instead of guessing or giving some repeating amount of new area as you unwind the poly wire, how about placing the poly wire so you actually are giving the cows the right amount of space to match the planned dry matter intake? 

So, how can we know how much pasture is actually out there – in real time, right now? It’s pretty simple actually. You need 3 basic things: 10 minutes once a week, a small battery-powered digital scale ($50) and a collapsible yard stick with sides of one foot each ($5). Using these, you can become an excellent manager of your land and grazing cattle.  Without these, you may be giving them too much space and wasting your forage resources. How do I know this? By having clipped some 125 pasture samples and sizing paddocks in 2010, I found it doesn’t take much more than a small part of an acre for a 50 cow herd to meet the 30% dry matter intake required.

How can you do this for yourself?? Identify a field where the herd will be in for the week ahead and scout the standing vegetation - then pick one average spot which the cows will graze. Next, outline one square foot of the standing pasture by placing your collapsible yard stick on the ground. Clip this one square foot sample down to about 3-4 inches (since you don’t want to graze the stand any shorter). Now weigh the sample, in ounces, on your digital scale. Next, multiply by .20 to figure much dry matter is there in that one square foot sample (since green growing plants contain basically 80% water). To then see how much dry matter is available in one acre worth of that sample you just clipped, multiply by 2850. The herd will not consume all of that, however, since they will trample some of it, urinate on parts and drop manure in some places - this is called refusal. Fortunately, the NRCS has done studies that show cows moved onto new paddocks every 24 hours will utilize 80% of what is given to them (refuse 20%). Since good graziers move their cows every 12-24 hours, this 80% utilization is figured by multiplying the first answer by .80. So the entire calculation is: weight of fresh sample in ounces x .20 = dry weight of sample; x 2850 = dry weight of an acre of the sample; x .80 = weight of an acre that’s available to utilize.

Now we can figure out what size paddock we will need for a herd of animals. It is safe to say that organic cows weighing about 1200 pounds will, on average, need about 45 lbs of dry feed per day (regardless if stored feed, fresh pasture or cardboard). And for this example, let’s exceed the organic minimum of 30% intake from pasture just a little, so let’s shoot for 33% (1/3) of their daily intake to come from pasture. Since 33% of 45 lbs is 15 pounds, then one cow will need 15 lbs from pasture for the day. Now say we have an acre of standing vegetation which we find to be 2000 lbs in dry weight from our clipping and quick calculation done right there in the field. Now take into account the 80% utilization rate. So in this example, a 2000 lb field stand will provide 1600 lbs to a herd grazing it. (2000 lbs x .80)

Since we figured one cow needs 15 pounds from pasture to get 33% dry matter intake, then that one cow put into that field of 1600 lbs needs only .009 acres of that stand (15 lbs/1600lbs=.009). Multiply that one cow by 50 cows (the herd) and 0.45 acres of that stand will be needed for 24 hours. And if the herd is moved up every 12 hours, they will need just 0.225 acre of that stand  - for the entire herd. That’s not even a quarter acre every 12 hours for an entire 50 cow herd!

Now imagine if you had been moving up the same 50 cows to a new acre of that same stand every 12 hours but you actually only needed to provide .225 ac to get the 33% -  I would say that you should’ve given yourself more dry matter intake credit than you did. You could have potentially saved standing vegetation for later use – either for more grazing or harvesting it for stored feed. By not truly knowing what was out there, you either didn’t take enough credit for actually pasture intake and/or you were going through pasture at a faster rate than you needed to.

Now, let’s look at that same 1600 lb pasture stand from a different angle. Now let’s say  the paper ration shows they’re getting 60% dry matter from the field. What size paddock would that same 50 cow herd need now? Take the same 45 lbs dry matter intake that one cow needs in a day (from whatever source - green grass to cardboard) but now multiply that by 60% to account for the new intake from pasture. One cow will now need to consume 28.8 lbs from pasture (versus the15 pounds as shown earlier). Next, we again divide the pounds from pasture needed by one cow (28.8 lbs) by the same 1600 pounds that is standing there and now one cow will require .018 ac to take in 60% from pasture. Multiply that again by 50 cows and an increased paddock size of .9 ac (.018 x 50) for 24 hours is now needed. For 12 hours, it’ll be half that (.45ac). If you’d been giving them 1 ac every 12 hours you again wouldn’t have taken enough dry matter intake credit.

But now let’s say you don’t use a single string poly wire system - all you have is unmovable barbed wire fencing of 1 acre paddocks. You also don’t have a nutritionist or paper ration. For this example let’s say you like to move your 50 cow herd into a new 1 acre paddock every 12 hours. How much IS that 1 acre providing in % dry matter intake, given the same 1600 lbs per acre in the stand to utilize? Those 50 cows can consume 32 lbs each from that 1 acre pasture paddock (1600 lbs available/50 cows). They still need to take in 45 lbs of feed daily, regardless if it’s from pasture or cardboard. In this example they are now receiving 71% of their dry matter intake from pasture (32 lbs from pasture /45 lbs needed from wherever). The 71% is the actual number which truly reflects what they are encountering and eating.

These examples are to show you that unless you walk out into your field and take a simple one square foot representative sample to truly know how much “stuff” is standing there ready to be grazed, you could be wildly off in your thinking about how much dry matter intake they are receiving. For those using the “back calculation” method of simply taking the winter time ration dry matter provided and then a spring time paper ration showing less dry matter provided in the barn and thinking that the remainder is coming from pasture… please realize that you may be actually short changing yourself in actual dry matter being consumed out in pasture. Taking a simple real life pasture sample and weighing it is the simplest way you will ever come close to providing the correct space to reflect what you want them to be taking in. This method allows you to understand what paddocks provide in terms of dry matter intake and to manage better during dry times as well as lush growing times. So for a $60 investment and 10 minutes a week, you can learn how to key into the correctly balancing your cattle needs with what the pasture provides.


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