Is Ross 308 or Cobb 500 better for Australian broiler contracts?

Both are the dominant genetics in Australia. Ross 308 tends to deliver slightly better FCR at typical Aussie catch weights (2.4–2.8 kg); Cobb 500 tends to deliver better breast yield at heavier weights. Your integrator usually picks the breed — check your placement docket.

Ross 308 Growth Chart 2026 — Target Weight, FCR & Feed Intake by Day

Q: What is the target weight for Ross 308 at day 42?

The Aviagen Ross 308 Performance Objective for day 42 is approximately 2.998 kg live weight as-hatched, with a target cumulative FCR of about 1.52.

Q: What weight should Ross 308 broilers be at day 21?

Around 1.012 kg live weight at day 21 (as-hatched) with a cumulative FCR near 1.29.

Q: What is the target FCR for Ross 308?

Cumulative FCR targets — day 21: ~1.29, day 28: ~1.36, day 35: ~1.44, day 42: ~1.52. These are Aviagen 2022 Performance Objectives; actual Australian contract targets often sit 0.03–0.08 higher.

Ross 308 as-hatched growth chart (day 1 – day 42)

Day	Body weight (kg)	Daily gain (g)	Cumulative feed intake (kg)	Cumulative FCR
1	0.049	7	0.011	0.898
2	0.065	16	0.026	0.972
3	0.085	20	0.045	1.000
4	0.108	23	0.070	1.031
5	0.135	27	0.101	1.062
6	0.166	31	0.140	1.087
7	0.205	39	0.187	1.114
8	0.245	40	0.238	1.135
9	0.291	46	0.298	1.161
10	0.343	52	0.368	1.183
11	0.398	55	0.446	1.202
12	0.457	59	0.532	1.220
13	0.520	63	0.626	1.234
14	0.468 → 0.586	68	0.728	1.242
15	0.655	69	0.837	1.256
16	0.727	72	0.954	1.269
17	0.803	76	1.078	1.281
18	0.881	78	1.209	1.293
19	0.862	81	1.348	1.303
20	0.945	83	1.494	1.313
21	1.012	85	1.647	1.287
22	1.099	87	1.807	1.335
23	1.188	89	1.973	1.345
24	1.279	91	2.146	1.354
25	1.371	92	2.325	1.363
26	1.464	93	2.510	1.372
27	1.558	94	2.700	1.380
28	1.616	95	2.896	1.365
29	1.748	95	3.096	1.395
30	1.843	95	3.301	1.402
31	1.938	95	3.510	1.409
32	2.033	95	3.722	1.415
33	2.128	95	3.938	1.421
34	2.222	94	4.156	1.427
35	2.296	94	4.377	1.440
36	2.408	93	4.599	1.437
37	2.500	92	4.824	1.443
38	2.591	91	5.049	1.449
39	2.681	90	5.276	1.454
40	2.769	88	5.503	1.459
41	2.855	86	5.731	1.464
42	2.998	85	5.960	1.520

Highlighted rows are the milestone days most Aussie growers benchmark against (7, 14, 21, 28, 35, 42). Values are as-hatched Ross 308 Performance Objectives — mixed-sex, on-farm body weight including feed in the intestinal tract.

How to read this chart on an Aussie contract

1 · Body weight (kg)

Target average live weight of an as-hatched flock at the end of that day. If your day-7 sample weighs 195 g, you're 5 % behind the 205 g objective and should investigate feed intake, brooding temp or water access — quickly.

2 · Daily gain (g)

Expected weight gain that day. Ross 308 peaks around 95 g/day between day 27–34, then tapers. If daily gain in the finisher phase is under 85 g, temperature or ventilation is usually the culprit.

3 · Cumulative feed intake (kg)

Total feed a bird should have eaten by the end of that day. Multiply by number of birds placed to get expected silo draw — Broiler Base Mate does this automatically and alerts you when a shed drifts more than 5 % off target.

4 · Cumulative FCR

Feed Conversion Ratio = feed consumed ÷ live weight. Aviagen 2022 objectives are ambitious; typical Australian contract targets sit 0.03–0.08 higher because of climate and processing style differences. Use our FCR Calculator to convert your batch FCR to corrected FCR (cFCR).

Ross 308 vs Cobb 500 — which is better for Aussie broiler contracts?

Metric (day 42)	Ross 308	Cobb 500
Body weight target	2.998 kg	3.020 kg
Cumulative FCR target	1.520	1.560
Feed intake per bird	5.960 kg	6.020 kg
Breast yield	~24 %	~25 %
Best for	Typical 2.4–2.8 kg catch weights, feed-cost focus	Heavier >3.0 kg birds, breast-yield contracts

Your integrator (Ingham's, Baiada, BPL Adelaide) usually picks the breed — check the day-of-placement docket. Both are elite modern broilers; the difference in a real Aussie shed is usually smaller than the difference between two growers.

FAQ — Ross 308 targets Aussie growers ask about

What is the target weight for Ross 308 at day 42?

Approximately 2.998 kg live weight as-hatched, with a cumulative FCR of about 1.52 per the Aviagen 2022 Performance Objectives. Australian contracts often catch a bit earlier (day 33–38) at 2.2–2.6 kg.

What weight should Ross 308 broilers be at day 21?

Around 1.012 kg live weight (as-hatched) with a cumulative FCR near 1.29.

What is the target FCR for Ross 308?

Cumulative FCR targets: day 21 ~1.29, day 28 ~1.36, day 35 ~1.44, day 42 ~1.52. Actual Australian contract targets sit 0.03–0.08 higher.

Is Ross 308 or Cobb 500 better for Australian contracts?

Ross 308 tends to deliver slightly better FCR at typical Aussie catch weights; Cobb 500 tends to deliver better breast yield at heavier weights. Your integrator usually picks — check your placement docket.

Compare your batch vs Ross 308 targets — live

Broiler Base Mate overlays your daily AI-weighed samples against the Ross 308 growth curve in real time — so you spot a shed lagging on day 12 instead of day 32. Built by a 3rd-generation Aussie broiler grower on a Baiada contract.

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