Ross 308 Broilers: Performance, Growth Curves & FCR Standards
A scientific guide to Ross 308 growth benchmarks, feed conversion ratios, carcass yields, and brooding environment.
Scientific Overview
The Ross 308 is the global benchmark commercial broiler strain bred by Aviagen. Selected for exceptional feed conversion efficiency, rapid daily weight gain, and high breast meat yield, achieving its full genetic potential requires precise brooding temperatures and phase-feeding programs.
Ross 308 Overview & Genetic Profile
The Ross 308 is defined as the world's leading fast-growing commercial broiler line engineered for maximum economic return in integrated poultry meat production, delivering high breast muscle proportion and low cumulative feed conversion ratio (FCR 1.45–1.52).
Ross 308 broilers are bred to adapt to both environmentally controlled tunnel ventilated houses and open-sided curtain systems, provided stocking density and air movement standards are strictly maintained.
Ross 308 Growth Chart & FCR Benchmarks
Under standard Aviagen performance criteria, target live weights and cumulative feed conversion ratios for mixed-sex Ross 308 flocks are:
- Day 1 Hatch Weight: 42–44 grams
- 7 Days Weight: 185–200 grams (FCR ~0.85)
- 21 Days Weight: 980–1,050 grams (FCR ~1.22)
- 35 Days Market Weight: 2.15–2.30 kg (FCR ~1.48)
- 42 Days Heavy Weight: 2.85–3.05 kg (FCR ~1.65)
Track your flock's growth trajectory with our Broiler Weight Tracker.
Feed Intake & Comparison vs. Cobb 500
A Ross 308 broiler consumes approximately 3.2 to 3.4 kg of total feed to reach a 2.2 kg market weight at Day 35. Below is a comparative performance matrix against Cobb 500:
| Trait / Benchmark | Ross 308 | Cobb 500 |
|---|---|---|
| Early Growth Velocity | Very Fast (High starter intake) | Moderate-Fast |
| Target FCR (to 2.2kg) | 1.45–1.50 | 1.47–1.52 |
| Breast Meat Yield (%) | 22.5–24.0% | 21.8–23.2% |
| Tropical Heat Hardiness | Moderate (Needs tunnel cooling) | High (Tolerates lower protein) |
Brooding Temperature & Rearing Guidelines
Day 1 chick floor concrete must reach 32°C before placement to prevent chick chilling, delayed yolk sac absorption, and gut stunting. Step down room temperature by 0.5°C daily until reaching 20°C at 27 days. Maintain minimum ventilation timing to extract ammonia (<10 ppm) and carbon dioxide (<3,000 ppm).
All scientific data, diagnostic criteria, and performance benchmarks presented on this page are derived from published peer-reviewed journals and official veterinary codes:
- Avian Pathology & Diagnostics: World Organisation for Animal Health (WOAH, 2023). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Paris, France.
- Poultry Diseases & Histology: Swayne, D.E., et al. (2020). Diseases of Poultry (14th ed.). Wiley-Blackwell / American Association of Avian Pathologists.
- Nutrition & Feed Chemistry: Leeson, S. & Summers, J.D. (2001). Commercial Poultry Nutrition (3rd ed.). University Books, Guelph, Ontario.
- Commercial Breed Standards: Aviagen (2024). Ross 308 & Cobb 500 Broiler Performance Objectives. / Lohmann Breeders (2024). Lohmann Brown Management Guide.