Calculating Forage Inventory

May 27, 2021

Tara Jo Bina
Countryside Feed Nutrition
Reducing feed costs has been a major conversation point recently. One of the best ways to save on out-of-pocket feed costs, is to push on farm forages wherever possible while still maintaining a well-balanced ration. Before pushing on farm forages, we must first make sure there is enough in inventory. Now is a great time to talk about forage inventory with your nutritionist for two main purposes: ration reformulation to potentially reduce feed costs, and planning for next year’s forage strategy. 
There are a few key pieces of information your nutritionist will need calculate forage inventory, and determine how hard you can push your on farm forages:
Dry Matter (DM) Pounds Available
Calculating the DM pounds available is fairly straight forward, but requires a little different information for different types of feeds:
  • Stored Forage Inventory = pounds per cubic foot * total cubic feet * DM % of the forage
    • Pounds per cubic foot: This can be estimated based on average values or calculated by measuring the forage usage in feet and dividing by the total pounds fed over a specified time period.
    • Total cubic feet: This will require different calculations based on storage method.
      • Bunkers = length * height * width
      • Upright Silos = diameter * silo fill (or current) depth
      • Bags = diameter * bag length * number of bags
    • DM % of the forage
  • Bale Inventory = average pounds per bale * number of bales * DM% of the forage
Inventory of dry hay and baleage can be calculated using the same formula, just be sure to know the DM% of the bales!
Current Forage Requirements
Now that we know how much forage is available, we need to look at how much is being used across the entire farm. This is where it is important to know the daily usage of each forage for EVERY group. Do not forget to include all groups that apply to your operation: lactating cows, dry cows, heifers, steers, etc.
  • DM pounds fed per group = DM pounds/head/day * number of animals in the group 
  • Total DM pounds fed = DM pounds group 1 + DM pounds group 2 + DM pounds group 3…
Once the total pounds available and current pounds required are calculated, you can estimate how many days of forage is left. If there is plenty excess forage until you plan to refill or harvest the next year’s forage, there is room to push on farm forage! On the other hand, if these projections show you will not make it until new crop forages are available, you may need to reevaluate rations to decrease forage, or consider other options! 

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