Shrink is the feed you harvested but never got to feed — dry matter lost between filling a pile and feeding it out. SilagePlan quantifies shrink by comparing drone measurements over time, turning an invisible cost into a number you can manage.
What shrink is
Between harvest and feed-out, silage loses dry matter to fermentation, heating, spoilage on the surface and shoulders, seepage, and handling losses at the face. None of that loss shows up on a scale ticket when you fill — it just quietly reduces how many tons come back out. Industry losses commonly run well into double-digit percentages of harvested dry matter, and poorly packed or poorly covered storage loses far more.
How SilagePlan measures it
Shrink is measured by flying the same storage regularly:
- A flight shortly after harvest captures the starting volume of each pile, bunk, or bag.
- Follow-up flights measure how much volume has actually disappeared.
- When SilagePlan knows the tons fed between flights, it compares the tons you actually removed against the change the drone measured. The gap — material that left the pile without being fed — is shrink.
On the inventory data table you’ll see two shrink columns:
- DM Loss Shrink — the estimated dry-matter loss for the pile, driven by its packing density.
- Total Volume Shrink — cumulative volume shrink across the pile’s flight history.
The Packing density & shrink section
The Packing density & shrink section on the Inventory V2 page is where shrink comes to life:
- Headline stats: total estimated shrink in dollars, average DM loss, and how much of it is recoverable if best-managed — plus how many piles have been measured.
- Per-pile and by-feed-type cards, sorted by dollar loss, so the most expensive problems surface first. Filter by All piles, In-use, or Unused.
- Shrink dollars are priced since harvest off each pile’s original tons — an editable baseline on in-use piles.
- Research-backed guidance on what drives density: the 800 rule, thin packing layers, prompt sealing with oxygen-barrier film, packing the entire face, and feed-out face management.
Because shrink is calculated from measured volume and your feed-out data, good used-tons entries and a good density are essential — see Working with silage density.
Why it matters financially
Shrink is a direct cost. If a feed is worth $60 per ton and a 3,000-ton pile shrinks 12%, that’s 360 tons — over $21,000 — gone from one structure. Multiply across every pile and every year and shrink is often one of the largest controllable costs on a forage program. It also distorts planning: a ration balanced against inventory that ignores shrink will run out earlier than expected.
Knowing your actual shrink lets you:
- Compare structures and practices (covered vs. uncovered, pile vs. bag, packing density) with real numbers.
- Justify investments in covers, tires, facers, or packing equipment with measured payback.
- Feed-budget realistically, so runout dates reflect the tons you will really have.
Getting good shrink numbers
- Fly on a regular schedule — monthly or at least seasonally. One flight tells you what you have; repeated flights tell you what you’re losing.
- Record used tons for each location between flights so the comparison has both sides.
- Keep feed types and locations consistent between flights in your records so measurements line up.
- Review the Packing density & shrink cards after each flight; a sudden jump usually points to a management issue at one structure while it can still be corrected.