Running out of silage mid-winter forces farmers into expensive spot-market fodder purchases, while over-ensiling ties up land and labor unnecessarily. This calculator works backward from your herd size and feeding period to tell you exactly how much silage to put up, accounting for dry matter content and any supplemental feed you plan to use alongside it.
Total Silage Required = Number of Animals × Daily Intake per Animal × Feeding Period (days) ÷ (1 − Supplemental Feed %), then adjusted for the silage's dry matter content since wetter silage requires a greater as-fed weight to deliver the same nutrition.
| Animal | Daily Silage Intake (as-fed) |
|---|---|
| Dairy cow (500 kg) | 20-25 kg |
| Buffalo | 18-22 kg |
| Growing cattle | 10-15 kg |
For 20 dairy cows fed 22 kg/day of silage for a 120-day winter period, with 20% of the ration coming from supplemental concentrate: Base requirement = 20 × 22 × 120 = 52,800 kg. Adjusted for the 20% supplement offset: 52,800 × 0.8 = ≈42,240 kg (about 42 tonnes) of silage needed for the season. Adding a 10% safety margin for spoilage during storage brings the target closer to 46 tonnes.
Plan for 8-12% spoilage loss even with well-managed pit or bunker silos, due to surface exposure and feed-out losses. Poorly sealed silos can lose 20% or more, so covering and weighing down plastic sheeting properly pays for itself.
Well-fermented maize or sorghum silage should sit at 30-35% dry matter. Silage that's too wet (below 25% DM) risks seepage and poor fermentation, while silage above 40% DM is harder to pack and more prone to mold.
Yes, to a point — shifting more of the ration to concentrate reduces bulk silage needed, but pushing concentrate too high (above 40-50% of dry matter intake) risks acidosis in ruminants, so this is a nutrition decision as much as a cost one.
Silage in a well-sealed bunker or pit can be safely stored for 12-24 months. Once opened, feed out at a rate that keeps the exposed face moving forward at least 15-20 cm per day to limit secondary fermentation and mold growth.