When analyzing forage reserves, practice makes perfect
Posted on: Dec 06, 2012
Several ranchers contacted us recently who wanted to get better at assessing stockpiled forage in pastures, and we commend them for doing their dormant season planning. Knowing how much forage is available for grazing in the dormant season is a key consideration in any efforts to minimize hay feeding and associated costs.
Determining animal days of forage available should be a key part of that assessment, and the process will generate much information for making management decisions. We described this process in an earlier post, but wanted to add information here.
First, when determining the number of animal days available in a pasture or portion of the ranch, recognize that accuracy will be a challenge. Getting good at quantifying an animal day simply takes practice. The more you do it, the better you'll get at it. We work with several ranches that assess forage availability in animal days either weekly or every other week. With such frequency, you're figures will gain accuracy as you go.
Second, don't forget to take a few forage assessments in a pasture if it has different levels of plant productivity, or has highly varied terrain. Take a comfortable number of samples within a pasture, and then average your animal day figures to arrive at an overall stocking rate for the pasture.
Third, don't forget to leave some forage behind for use by wildlife (forage and cover) and as a source of litter cover.
Fourth, compare your forage availability estimates to your actual use data. If, for example, you estimated you had 10,000 animal days worth of forage in your pasture, and you ran out of feed at 8000 animal days, then your estimates need to be re-calibrated. Don't make the same mistake when moving your herd onto subsequent pastures.
Fifth, get good at assessing forage availability without having to step off an animal day's worth of feed as was described in that earlier post. Several ranchers we work with, through years of practice, can walk into a pasture and tell you what the stocking rate should be as measured in animal days per acre. This is a terrific skill to have. By assessing their forage availability regularly (weekly or every other week), they know how much forage is in front of their herd for grazing and can minimize costly hay feeding in the process. This level of confidence can help cut costs.
Last, you may need to gain confidence converting your stocking rate figures from aimal days per acre (ADAs) to acres per animal unit month (Ac/AUM), especially when dealing with federal land management agencies. These agencies regularly use months as the unit of time, rather than days. To convert from ADAs to Ac/AUM, take the reciprocal of your ADA figure and then multiply by 30 (days per month). For example, if you determined you had 12 ADAs available in a pasture, this may also be represented by 2.5 Ac/AUM (1 / 12 * 30 = 2.5). If you want to show the stocking rate figure in AUM/Ac, versus Ac/AUM, simply take the reciprocal of your Ac/AUM figure. For example, 2.5 Ac/AUM is also 0.4 AUM/Ac (1 / 2.5 = 0.4). This will help you communicate stocking rate estimates to federal agencies.