Fire up the forage calculator

By Mike Rankin


The onset of winter means digging into those stored forage inventories with the realization that any forage additions can only be accomplished in the form of outgoing cash.

There are many good reasons for taking a forage census this time of year. Counting bales, estimating silage reserves, and determining livestock needs is not only a good business practice but also a requirement made by many lenders when balance sheet calculations are made.

Here’s a quick summary of the approach that needs to be taken:

Baled hay:

Baled hay is relatively easy. Make a count and determine the weight per bale for each type of hay made (and perhaps cutting). Bale weights must be accurate. If a "guess" is off by 100 or more pounds per large bale, this can result in a significant error over a season's worth of harvested forage. Also be sure to take into account moisture, if feed needs are being determined on a dry matter basis.

Silage:

There are two types of silage inventory estimates: inaccurate and almost accurate. An inaccurate estimate is easy and can be done from the comfort of your living room. An almost accurate estimate takes some effort.

Silage bales and, to a lesser degree, silo bags lend themselves to relatively solid estimates. In the case of baleage, an accurate weight, bale count, and moisture are all that is needed. For bags, which tend to have less variation front to back than other types of silos, there are charts and spreadsheets that can be used. Note that unfilled bag ends need to be accounted for, as do feeding and handling losses.

Horizontal bunker or silage piles have many inherent variables when it comes to accurately estimating stored forage. Density (pounds per cubic foot); length; width; dome height and slope; and ramp length all differ between storage units.

There are many spreadsheets that can help with this task, but it's up to you to safely obtain accurate dimensions. It's good to get this job done before weather conditions totally disintegrate. Further, given the size of some silage piles and bunkers, a misrepresentation of actual density can result in an inventory estimate that is significantly off the mark.

Tower silos have the advantage of a fixed diameter. Still, there is the realization that more forage exists in the bottom 10 feet of a silo than in the top 10 feet. If some silage has already been fed from a tower silo (top or bottom), it needs to be accounted for using a silo chart.

Forage quality

Once the forage census duties are complete, the next chore is to match forage inventories with livestock needs. Inventory livestock by age and/or feed requirements. Forage quality plays a large role in feedout rates. For this reason, forages need to be tested so that reasonable ration inclusion rates can be calculated. Your nutritionist can help with this task.

Finally, begin multiplying animal numbers by days and forage needs, then compare total forage needs with forage inventories. Keep straight whether calculations are being made on an as-fed or dry matter basis.

Most university extension services have a variety of paper and computer-based worksheets to help navigate through this entire process. Yes, it can be mundane, but the outcome of a thorough forage inventory and winter-feed management plan can pay big dividends. Now is the time to get it done.