The broiler growth chart ends at day 49, but the money question starts there: every extra day in the house is a bet that the pounds gained will be worth more than the feed they cost. In the finisher phase that bet gets worse by the week — feed conversion climbs, daily gain flattens, and the same ton of feed buys fewer saleable pounds than it did in week four. This chart turns the breeder weight and FCR tables into catch economics: what each extra week actually costs per bird, what it costs per pound of gain, and the break-even live price that decides whether extending is worth it.
Weight and Conversion by Catch Age
Source: Cobb-Vantress Cobb500 Performance & Nutrition Supplement (2022) and Aviagen Ross 308 Broiler Performance Objectives (2022), mixed-sex birds under standard management. Feed derived from breeder weight and FCR objectives.
| Breed | Catch Age | Live Weight | Live Weight | Cumulative FCR | Cumulative Feed/Bird |
|---|---|---|---|---|---|
| Cobb 500 | 35 days | 2,190 g | 4.83 lb | 1.53 | 7.24 lb |
| Cobb 500 | 42 days | 2,910 g | 6.41 lb | 1.69 | 10.69 lb |
| Cobb 500 | 49 days | 3,300 g | 7.26 lb | 1.80 | 12.93 lb |
| Ross 308 | 35 days | 2,230 g | 4.92 lb | 1.50 | 7.24 lb |
| Ross 308 | 42 days | 2,950 g | 6.50 lb | 1.65 | 10.68 lb |
| Ross 308 | 49 days | 3,350 g | 7.39 lb | 1.78 | 13.00 lb |
- Cobb-Vantress. Cobb500 Broiler Performance and Nutrition Supplement (2022). Download PDF
- Aviagen. Ross 308 Broiler Performance Objectives (2022). aviagen.com
The Cost of One More Week
The table below is the whole argument. It shows what happens between catch ages — how many pounds a bird gains, how much feed it eats to gain them, and what that feed costs per pound of gain at the example $0.50/lb:
| Extension | Breed | Gain per Bird | Feed per Bird | Incremental FCR | Feed Cost per lb of Gain |
|---|---|---|---|---|---|
| Day 28 → 35 | Cobb 500 | 1.26 lb | 2.58 lb | 2.05 | $1.03 |
| Day 35 → 42 | Cobb 500 | 1.59 lb | 3.45 lb | 2.17 | $1.09 |
| Day 42 → 49 | Cobb 500 | 0.86 lb | 2.24 lb | 2.60 | $1.30 |
| Day 28 → 35 | Ross 308 | 1.32 lb | 2.76 lb | 2.09 | $1.05 |
| Day 35 → 42 | Ross 308 | 1.59 lb | 3.44 lb | 2.17 | $1.08 |
| Day 42 → 49 | Ross 308 | 0.89 lb | 2.32 lb | 2.63 | $1.32 |
Read the last two rows closely. Extending a Cobb 500 flock from day 42 to day 49 buys about 0.86 lb per bird — and costs about $1.30 per pound of that gain in feed alone, before heating, water, labor, or the extra mortality days in the house. The same week in the grower phase (day 28 → 35) costs about $1.03 per pound of gain. The finisher week is roughly 25% more expensive per pound than the week before it, because the bird is converting at 2.60 instead of 2.05.
Per house, the day-42-to-49 extension on 30,000 birds is about 25,700 lb of extra live weight for about 67,200 lb of extra feed — roughly $33,600 of feed at $0.50/lb. Whether that is a good trade depends entirely on one number: what your contract pays per pound.
The Break-Even Test
The break-even live price for an extension is simple arithmetic: extra feed cost ÷ extra pounds gained. At $0.50/lb feed:
- Day 42 → 49, Cobb 500: $1.30 per pound of gain. If your live bird is worth less than $1.30/lb, that week loses money on feed alone.
- Day 35 → 42, Cobb 500: $1.09 per pound of gain. A weaker break-even — but this week also delivers the biggest absolute gain (1.59 lb/bird), which is why most contracts target this window.
- Feed price moves everything: at $0.60/lb feed, the day-42-to-49 break-even rises to about $1.56/lb. At $0.40/lb it falls to about $1.04/lb. Check your own delivered price before every catch decision — the same catch date can be profitable or unprofitable on feed price alone.
And the FCR penalty keeps going past day 49. Cumulative FCR is climbing steeply by then — Cobb 500 runs 1.80 by day 49 against 1.69 at day 42 — so birds caught late cost more per pound all the way to the scale. This is why most grow-out programs treat day 42–49 as the catch window and treat anything beyond it as an exception that must justify itself with a price premium.
When to Catch: Decision Tree
Your integrator's target weight band and settlement terms decide what "on time" means. Most contracts pay best inside a weight window and dock birds outside it — confirm your current band, because a bird caught at 7.5 lb in a 6.0–6.5 lb program is not worth more, it is worth less. The breeder chart tells you what the bird can do; the contract tells you what it should do.
Weigh 30–50 birds per house with the standard protocol and compare against the growth chart for your strain and age. If the flock is behind target, extending to "catch up" usually fails — the growth rate bands explain why, and the ADG chart shows what the remaining weeks would actually deliver. If the flock is on target, the catch decision is pure economics.
Pull your current delivered feed cost per pound, multiply the incremental FCR for the extension week (2.60 for day 42 → 49 on Cobb 500), and compare the result to what your contract pays per pound of live bird. Feed cost per pound of gain = incremental FCR × feed price. If break-even exceeds the bird's value, the extension loses money before the first extra pound is gained.
A wide flock caught late gets wider — small birds keep eating without reaching the band, big birds pass it. Calculate CV% from the last weigh-in (see the uniformity guide). If uniformity is poor, fixing the spread usually returns more than extending the average, and the extra week magnifies the problem instead of solving it.
Every extra week is an extra week of heat-stress exposure, disease pressure, and mortality risk — see the heat stress guide for what late-summer finishers face. In hot weather, birds gain less and drink more per pound gained, so the extension costs more and delivers less than the chart above. Health status matters the same way: a flock you would not extend on a good day is a bet, not a strategy.
Make the call with the break-even number written next to the catch date, then compare what actually settled against the projection using the settlement calculator. The growers who improve this decision are the ones who kept the record — one decision at a time, tied to the price that justified it.
Tracking Catch Decisions in Poultry Log
When entry/exit counts, sample weights, feed deliveries, and mortality are logged in Poultry Log, the flock's actual position against the target curve is visible before the catch decision is made — and the feed math behind the break-even comes from your own consumption history, not an example price. Each flock's catch weight, feed used, and settlement feed the profitability dashboard, where you can see what catch timing actually did to margin across flocks: the record that turns this chart from a good argument into a habit that pays.
- 2026-10-05: Initial version. Catch-age weight/FCR table, incremental extension economics, break-even test, and catch decision tree.