How to calculate how many bags of corn silage your herd needs
Published: 02 sept 2026 · Agrícola LG Calderón
A simple formula, examples for 5, 10 and 20 animals, and a table to know how many 35 kg bags to buy per week or per month.
Short answer: multiply number of animals × kg of silage per animal per day × days, and divide by 35 (kg per bag). Example: 10 cows × 35 kg × 30 days = 10,500 kg ÷ 35 = 300 bags per month.
The formula
Bags = (animals × kg per animal per day × days) ÷ 35
Kilos per animal depend on whether silage is the base of the diet or a supplement. As a general reference:
| Use of silage | kg per animal/day |
|---|---|
| Pasture supplement | 10–15 |
| Base of the diet (dry season) | 30–40 |
| High-producing milking cow | 35–45 |
| Fattening steers | 25–35 |
| Weaned calves | 8–15 |
More detail in How much silage does a cow eat per day?.
Examples
| Herd | Ration | Per week | Per month (30 days) |
|---|---|---|---|
| 5 cows | 15 kg (supplement) | 15 bags | 64 bags |
| 5 cows | 35 kg (base) | 35 bags | 150 bags |
| 10 cows | 35 kg (base) | 70 bags | 300 bags |
| 20 cows | 35 kg (base) | 140 bags | 600 bags |
In kilos: 300 bags = 10,500 kg; at CRC 100 per kg, the monthly cost for those 10 cows would be CRC 1,050,000 (CRC 3,500 per bag).
Tips so you don't run short
- Add a 5–10 % margin for leftovers and animals that eat more.
- Buy for 2–4 weeks and restock: that way the silage is always fresh. See how to store the bags.
- For the whole dry season (about 120 days), reserve early: see the dry-season calendar.
Want us to run the numbers? Message us on WhatsApp at +506 8718 5094 with the number of animals and their stage, and we'll send you a quote.
The figures in this guide are general management references; for a precise ration consult your veterinarian or animal nutritionist.
Frequently asked questions
How many bags of silage do I need for 10 cows?
At 35 kg per cow per day, about 70 bags of 35 kg per week or 300 per month. If silage is only a supplement (15 kg), about 30 bags per week.
How many kilos are in a bag of silage?
Our bags are 35 kg.
How much does it cost to feed 10 cows silage for a month?
About 300 bags (10,500 kg). At CRC 100 per kg that is roughly CRC 1,050,000 per month when silage is the base of the diet.
Should I buy all the dry-season silage at once?
It is better to reserve the total amount and receive it in 2–4 week deliveries, so the silage is always fresh and you avoid storage problems.