Keep the heifers: compound interest, explained with ten cows

Two ranchers. Ten cows each. Same pasture, same rain, same luck. Thirty years later, one of them is down to a couple of cows. The other is running seventeen hundred head.

Nothing about the cows was different. One small decision, made every fall, was.

The decision: sell the calves, or keep some

Every spring most cows have a calf — call it nine calves from ten cows. Half are steers, half are heifers. Rancher one sells all nine every year (a good steer calf brings about $2,100 in Texas right now, so that's a real check). Rancher two sells the steers too, but she keeps the heifers.

Two years later those heifers have calves of their own. Then their daughters do. In our simple model the herds look like this:

Model: 88% of cows wean a calf, half are heifers, heifers calve at 24 months, 15% of cows culled each year, no drought, death loss or pasture limit. It's a teaching model, not a ranch plan.

Interest is calves. Compounding is keeping the heifers.

Swap the cows for money

Put $10,000 somewhere for 30 years and leave it alone:

• Average U.S. savings account (0.37%) — about $11,200.
• High-yield savings (about 4%) — about $32,400.
• Broad stock index fund (about 10% historical average) — about $174,500. It's an average; some years are brutal.

Same money. Different pasture. A low-rate savings account isn't a bad herd — it's a herd where the bank keeps the calves.

Why starting early beats saving more

The Department of Labor's own example: one person saves for ten years, from 20 to 30, then stops — $11,000 total. Another starts at 30 and never stops — $35,000 total. At 7% a year, the early saver ends up with about $168,500; the late saver with about $147,900. The heifers born in your twenties have granddaughters by the time you're sixty.

The quiet cow thief: fees

Imagine someone takes one cow in a hundred out of your pasture every year. After 35 years, nearly 30% of the herd is gone. That's what a 1% fee does. The DOL's numbers: $25,000 over 35 years at 7% grows to about $227,000 with 0.5% in fees — and about $163,000 with 1.5%. One point more in fees, 28% less money.

Three things to do with this

1. Cash you aren't touching doesn't have to sit in the 0.37% pasture. High-yield savings or Treasury bills pay roughly ten times more with very little risk.
2. Money you won't need for ten years can go where it has calves. The boring, common answer is a broad, low-cost index fund inside a retirement account.
3. Find the fee line on every account you own and read it.

Sources

• FDIC national deposit rates via FRED (SNDR), September 2026
• Bankrate high-yield savings survey, September 2026
• Aswath Damodaran, NYU Stern — historical S&P 500 returns, 1928–2025
• U.S. Department of Labor — “The Magic of Compounding” and “A Look at 401(k) Plan Fees”
• USDA AMS Texas weekly cattle auction summary, Sept. 25, 2026