In order to get forage yield of your pastures you may need to do a bit of clipping in different sites around the pasture. Find a random spot in the pasture, and stake out a 1 ft x 1 ft area. Clip the forage inside that square to about a 2-inch (4. 5 cm) height, and put it in a brown paper bag. Label the bag to know which pasture it came from. Ideally, you should take about 10 or more of such clippings in the same pasture to get an albeit small representative sample size, however two to five clippings in random spots (never choose just the best areas) will work. Take those forage samples, weigh the container you are going to put them in, then weigh the samples plus the container. To eliminate the weight of the container including the sample subtract the weight of the container to get the weight of the sample. This is useful if your weigh scale does not have a “tare” or zeroing function on it (most scales should). If your scale can be zeroed, then set the container on it, tare it to zero, and then put the sample in. Dry the sample in a microwave oven, each session 1. 5 to 2 minutes long, and keep a cup of water with the sample in the microwave to prevent it from burning. Weigh the sample after each session, repeating until the weight of the sample is no longer decreasing. Record the weight as a dry weight, and repeat with the other samples collected. Once you have dried and weighed all the samples, take an average of all the final dry weights. To get forage yield in terms of pounds per acre, simply multiply the average result by 43,560 square feet to convert pounds per square foot to pounds per acre. 1 acre = 43,560 square feet. Another method, which is much less time-consuming and tedious, but takes much more practice and head-arithmetic, is using a grazing stick. A grazing stick is basically just a yard stick with formulas on the side to calculate the amount of forage is in your pasture. Put the end of the stick down to the ground, and measure the height of the sward 15 to 20 times (never stretching the leaves of the plants up the stick) to get an average forage height in inches. Next, estimate forage density based on green plant cover. This is done visually, looking directly down where you are standing. Density is the amount of ground surfaced by the forage stand. It is usually based on three criteria: less than 75 percent (> 75%), between 75 to 90 percent (75 - 90%), and more than 90% (<90%). Based on the forage type of your stand and the density estimate, multiply average plant height by the dry matter yield, in pounds per acre-inch, of the forage type[1] X Research source [2] X Research source . This will give you an estimate of the amount of forage you have available per acre. Please see the references below for tables of forage types and more info on calculations below. For example, with multiple measurements you came up with 10 inches (25. 4 cm) of forage height. Looking at the density, you estimate that there is around 80% plant density. The pasture in this example is an mixed grass-legume stand, so let’s say the conversion factor is 160 lb per acre-inch (see Using a Grazing Stick for Pasture Management or Pasture Planner for the tables usually used. Note the first link is from the Southeastern part of the United States, the second is based on pasture productivity for Western Canada, and are all average values for the respective regions). Thus, 10 in. x 160 lb/acre-in. = 1,600 lb/acre.
Another method, which is much less time-consuming and tedious, but takes much more practice and head-arithmetic, is using a grazing stick. A grazing stick is basically just a yard stick with formulas on the side to calculate the amount of forage is in your pasture. Put the end of the stick down to the ground, and measure the height of the sward 15 to 20 times (never stretching the leaves of the plants up the stick) to get an average forage height in inches. Next, estimate forage density based on green plant cover. This is done visually, looking directly down where you are standing. Density is the amount of ground surfaced by the forage stand. It is usually based on three criteria: less than 75 percent (> 75%), between 75 to 90 percent (75 - 90%), and more than 90% (<90%). Based on the forage type of your stand and the density estimate, multiply average plant height by the dry matter yield, in pounds per acre-inch, of the forage type[1] X Research source [2] X Research source . This will give you an estimate of the amount of forage you have available per acre. Please see the references below for tables of forage types and more info on calculations below. For example, with multiple measurements you came up with 10 inches (25. 4 cm) of forage height. Looking at the density, you estimate that there is around 80% plant density. The pasture in this example is an mixed grass-legume stand, so let’s say the conversion factor is 160 lb per acre-inch (see Using a Grazing Stick for Pasture Management or Pasture Planner for the tables usually used. Note the first link is from the Southeastern part of the United States, the second is based on pasture productivity for Western Canada, and are all average values for the respective regions). Thus, 10 in. x 160 lb/acre-in. = 1,600 lb/acre.
Some rules of thumb to remember for utilization rate are: the longer the animals remain on pasture, the lower the utilization rate must be in order to reduce incidence of overgrazing. Also, the poorer the pasture, the less forage is available to eat, and the less the animals are able to graze, therefore the lower the utilization rate.
Keep records of your pasture forage yields on a spreadsheet so that you are able to see trends and begin to develop your own benchmark. This may also help you see where you can improve your grazing management practices. Grazing sticks can be purchased at a local county extension office or applied research organizations. Please note that grazing sticks are actually much more ideal for use on tame pastures. They tend to be less reliable when measuring native grasslands due to the much higher variability that can be found in such areas, unlike with a tame pasture that is almost always fairly uniform across the land base.
Note that calf weight is “included” in the cows’ weights when calculating for cow-calf pairs. As a general rule, calves do not eat a significant amount of forage until they reach weaning. This step is of great importance because today’s modern cow size is much larger than the size of the cow that was common in the 19th and 20th centuries. Cow size must be taken into account to reduce the chance of overgrazing. Larger cows eat more than smaller cows, therefore less large cows can be grazed than small cows.
This percentage is also known as the amount of forage or feed an animal will eat per unit of body weight per day. From the example above, a 1250-pound cow can be expected to eat 0. 025 pounds of forage per pound of body weight per day.
