How to Estimate Forage Quantities in a Pasture

We can’t manage what we can’t measure, and I’ll bet every grazier reading this has some measure of their Livestock Inventory, if for no other reason than that you have to for the taxman! End of year reporting compliance for the accountant dictates we know how many mouths we feed and hence we have a record of the demand side of the forage equation.

Understanding the Supply Side of the equation

You know that conversation you keep in your head when you get told by the shop assistant that they ‘ran out of stock and it’s a two week wait til the back order gets in…’ for something you need today. “But it’s your job to know your stock levels you bozo and I drove all the way in here to pick it up too…”.

Though you don’t actually say any of that, which is just as well, because it would be a bit rude when you don’t know your own inventory levels at the farm and I mean forage inventory, the supply side of the equation.

For me, forage inventory does not mean hay bales in the shed, it means being able to walk into a pasture as the Herd is going in or coming out after a graze, and come up with a rough enough estimate that I can be confident in. The great result of this is I can then budget my forage out until Spring.

The reason this is oh so important is that without it I am driving blind, weaving down the highway with a million bucks worth of livestock in the back without really knowing if I can navigate this thing to the end of the season. If I get there without needing to buy in feed or sell a few it will be dumb luck. Can you imagine being a pilot, with a load of passengers in the back, and not knowing if the fuel reserves exceed the demand to get to the end of the landing runway? No you can’t!

Enough of the castigation. So we don’t know how to measure grass or forage … then let’s learn how pronto and get cracking with better grazing management.

So how do we Measure Forage Quantities?

This is not about crawling around on the ground cutting grass into the oven and getting all scientific, (though that would be great, it will stop you actually doing it!) This is all about a subjective ‘you sized’ feedback loop that means you know what you are talking about when you say there is 2 days feed in that thar pasture.

  1. To know the supply, you gotta learn the demand
  2. To learn the demand you gotta know what the herd eats in a graze, ie
    1. Herd daily feed intake, eg 100 Cow/calf x 30lb/day for each stock class = 3,000 lb/day
    2. Time = days in the pasture, eg 5 days (whether a short or long graze, the cows eat the same/day!)
    3. Area = acres in the pasture, eg 25 acres
      So forage consumed in a graze = a x b / c  = 3000 x 5 / 25 = 600lb/ac
      So forage consumed in a graze = (total Herd rating) x (Days in pasture) / Acres
      = lb/day x days / acres … gives a result of Lb/Ac for the graze.

Now you have a number for the grass harvested in a graze and it doesn’t matter if it was a short graze or a long graze. And so, begins your journey to an immensely valuable skill that will serve you well.

Complete the Process

To complete the feedback loop

  • pick a pasture you just moved a herd into, or are about to, go stand in the middle of and look into the forage and across Take a mental snapshot or better yet, a photo
  • come back to the same spot when you move the herd out of that graze and dial up the memory/photo of how it was
  • the graze yield harvested number you worked out before, eg 600 lb/ac, is the difference between what it was and what it is… so your graze took out 600lb/ac of dry matter forage
  • Go to the next pasture the herd is moving into and do the same thing
  • I promise within maybe a dozen grazes or less you will be confident in your assessment and be able to pick the difference between 400 and 500 lb/ac available to comfortably graze out.

Take that to the bank of grazing management skills acquisition

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