The three broiler chicken growth stages
| Stage | Day range | Feed type | Shed temp | What's happening |
|---|---|---|---|---|
| Brooding | 1–14 | Starter | 30–34°C | Rapid organ development, most vulnerable to cold stress and early mortality |
| Grower | 15–28 | Grower | 24–28°C | Fastest daily weight gain — 80–100g/day on a well-managed shed |
| Finisher | 29–42+ | Finisher / Withdrawal | 20–24°C | Weight gain slows, FCR climbs, birds approach catch weight |
Brooding phase (day 1–14) — the highest-risk window
Chicks arrive at day-old weight (~40g) with almost no ability to self-regulate body temperature. This is why brooding shed temperature (30–34°C, stepping down gradually) matters more than anything else in the first two weeks — a cold shed in the first 72 hours is the single biggest driver of early mortality on a broiler batch. Feed and water need to be within a few centimetres of every chick from hour one; birds that don't start eating in the first 24 hours rarely catch up.
By day 10, a Ross 308 or Cobb 500 chick should be sitting around 250–280g. Track this against your breed's growth chart (see our Ross 308 Growth Chart or Cobb 500 Growth Chart) — birds tracking more than 10% under target at day 10 are worth investigating (temperature, water pressure, feed access).
Grower phase (day 15–28) — the fastest-growing window
This is where feed conversion is most efficient and daily gain peaks. Birds move onto grower feed (higher energy, lower protein than starter) and ventilation demand rises sharply as body mass and heat output increase. Silo feed-drop timing gets critical here — an empty feeder for even a few hours during this window costs real growth that's never fully recovered.
Finisher phase (day 29–42+) — approaching catch weight
Daily gain slows as birds approach mature size, and FCR naturally climbs (each extra kilo of growth costs more feed than the last). Most Australian broiler contracts — Ingham's, Baiada, BPL Adelaide — catch somewhere between day 35 and day 42 depending on target weight and market demand. Withdrawal feed (no medication) is typically introduced 3–5 days before the first catch.
FAQ
How long does it take a broiler chicken to reach market weight?
Most Australian contracts catch between day 35 and day 42, when a Ross 308 or Cobb 500 bird weighs roughly 2.4–2.9 kg depending on target and breed.
When do broilers grow fastest?
Daily weight gain peaks during the grower phase (roughly day 15–28), when birds can gain 80–100g per day on a well-managed shed.
What's the biggest risk period for a broiler chicken batch?
The brooding phase (day 1–14) — chicks can't regulate their own body heat yet, so shed temperature and early feed/water access drive most of the mortality risk for the whole batch.
Track every stage against the real growth curve
Broiler Base Mate's Flock Forecast plots every weigh-in against the Ross 308 / Cobb 500 growth curve per shed, live — so you know within a day if a shed is tracking off target.
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