Ross 308 vs Cobb 500: Broiler Genetics Standards Comparison
Side-by-side scientific comparison of global commercial broiler bloodlines, growth curves, breast yield percentages, and metabolic tolerances.
Scientific Overview
Ross 308 (Aviagen) and Cobb 500 (Cobb-Vantress) represent the dual monopoly of global broiler poultry genetics. Deciding between these packages requires balancing parameters such as growth velocity, late-stage feed conversion efficiency, breast meat processing yields, and physiological tolerance of warm climates or altitude stress.
Genetic Objectives & Anatomical Profiles
Ross 308 is selected for early structural development, strong skeletal frame sizing, and rapid body weight gains (growth velocity) during the starter and grower phases. This bloodline provides excellent FCR values in short crop cycles (<35 days).
Cobb 500 is bred specifically for portioning and processing yield. It features a rounder breast conformation that yields 1.5% to 2.2% higher white breast meat cutouts compared to Ross. Cobb exhibits superior FCR when fed high-density diets in longer crops (38 to 45 days).
Comparative Weight Trajectory Guide (g)
Standard commercial growth curves under thermo-neutral ventilation guidelines:
| Age (Days) | Ross 308 Weight (g) | Cobb 500 Weight (g) | Ross FCR Target | Cobb FCR Target |
|---|---|---|---|---|
| Day 7 | 185 g | 182 g | 0.92 | 0.93 |
| Day 14 | 475 g | 470 g | 1.12 | 1.13 |
| Day 21 | 970 g | 965 g | 1.26 | 1.27 |
| Day 28 | 1,610 g | 1,600 g | 1.39 | 1.39 |
| Day 35 | 2,280 g | 2,295 g | 1.52 | 1.51 |
| Day 42 | 2,990 g | 3,015 g | 1.65 | 1.63 |
Nutritional & Environmental Hardiness Profiles
Climatic Tolerance: Cobb 500 shows slightly higher heat tolerance in warm, tropical climates. Its genetic selection focuses on bird survival under high humidity. Ross 308 has an active appetite, requiring high air speeds (minimum 2.5 m/s) in tunnel houses to remove metabolic heat.
Amino Acid Density: Cobb 500 requires higher digestible Lysine densities in starter and grower formulations to maximize breast yield. Ross 308 is highly adaptive, converting lower density diets efficiently.
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.