OSU Sheep Team

Jeff McCutcheon, Knox County Extension Educator

It is amazing that graziers say their focus is on the forage but they don’t measure it.
Most graziers use measurements related to animal production, like the reading from the bulk tank or the weight of animals on the auction sale receipt. These are good items to keep track of because they relate directly to income but they are not timely enough to help graziers make grazing decisions in their operations.

Measuring and recording the forage performance can be useful in making several grazing decisions. Of course the measurements you take should be in the context of the objectives and goals of your operation. Taking measurements just as an exercise makes no sense. Taking measurements that relate back to your objectives and goals can help you monitor progress and improve your operation.

There are lots of ways to measure forage such as, pasture sticks, falling plate meters, rising plate meters, electric pasture probes, and even the tedious method of cutting. With little expense, graziers can consistently determine how much forage is available by simply walking their paddocks.

One problem with measuring forage is that it is a dynamic, living community of plants that is highly variable. To overcome the variability, many samples must be taken in order to accurately estimate how much forage is there. This can be time consuming and tedious. Usually 20-30 samples are recommended per pasture or paddock. The second problem is that the amount of forage available is always changing; animals are consuming leaves and plants are growing. To account for this constant change, measurements need to be taken on a regular basis, usually every seven to ten days.

The most accurate method used to determine the amount of forage available is cutting. Cutting is simply to take a known area, usually a one or two foot square, cut all of the forage in that area, dry it down completely, weigh the sample and convert it to pounds of dry matter per acre. Taking samples in this manner does take time. Most people use it to calibrate some other faster method of measurement. In managing your operation, accuracy is not as important as consistency. Faster methods can give consistent and fairly accurate results.

The easiest measurement of forage we can do is height. There seems to be some common confusion about using plant height to measure forage. Do livestock eat inches of forage or do they eat pounds of forage? Actually they eat pounds. To make it simpler, we take water out of the equation and say pounds of dry matter. Since the primary function of forage is to be used as feed, then converting its measurement into feed terms makes sense.

Two factsheets from West Virginia University; A Falling Plate Meter for Estimating Pasture Forage Mass and Estimating Pasture Forage Mass from Pasture Height are good references for graziers on measuring forages. Rayburn & Lozier do a good job of discussing using a ruler, a falling plate meter and a rising plate meter. (http://www.caf.wvu.edu/~forage/foragelstcenter.htm) Any of those tools could easily give you consistent information that is accurate enough to use in your management.

If you make time to determine average pounds of dry matter per acre for each paddock once a week, it would reward you with huge dividends. It will tell you how much forage you have in each paddock, which in itself is useful information. You will quickly see which paddocks need to be grazed next. If growth has stopped, you can quickly calculate how many days of forage you have left to graze.

Doing it on a weekly basis also allows you to calculate more useful information. Two consecutive weekly measurements can be used to calculate how fast the forage is growing. You can determine if you to a need to change your management because growth has either increased or decreased. Looking at a years worth of data you could calculate how much forage you actually grew and if you can carry more animals. It can help you identify the top yielding paddocks and the lowest yielding paddocks. You can determine ways to make the lower yielding paddocks produce more. Using measurements next year will help you determine if what you tried actually worked.

Measuring pastures and using the data is not the most exciting topic in grazing management. But it is one of that will make you effective in your management.