Why Tracking Broiler Growth Matters
A broiler growth chart tells you whether your flock is on track to meet target weight at processing. When birds fall behind expected weight by week 3 or 4, the gap rarely closes completely. Early detection of growth problems gives growers time to investigate and correct the cause — whether it is environmental, nutritional, or health-related — before the loss is locked in at settlement.
Growth targets vary by breed, feed program, and target processing weight. The numbers in this guide are based on Cobb 500 and Ross 308 performance objectives, which are the most common commercial broiler breeds in North America and Europe. Your integrator or hatchery can provide the specific growth targets for your flocks.
Week-by-Week Growth Targets
Week 1 (Days 0–7)
Target weight: 0.35–0.40 lb (160–185 g). Cumulative feed consumption: approximately 0.35–0.45 lb (160–200 g) per bird. Week 1 sets the trajectory for the entire flock. Chicks should gain 4–5 times their day-old body weight by day 7. First-week mortality target is under 1.5%. Chicks that are below target weight at day 7 rarely catch up completely.
Week 2 (Days 7–14)
Target weight: 0.85–1.05 lb (385–480 g). Cumulative feed consumption: approximately 0.95–1.15 lb (430–520 g) per bird. This is a period of rapid relative growth. Feed intake should increase sharply as chicks transition from starter feed. Water consumption should be approximately 1.5–2.0 times feed consumption by weight.
Week 3 (Days 14–21)
Target weight: 1.65–2.00 lb (750–910 g). Cumulative feed consumption: approximately 2.10–2.50 lb (950–1,135 g) per bird. By week 3, differences between houses in the same flock become apparent. Comparing weights between houses at this stage can identify environmental or management differences that need correction.
Week 4 (Days 21–28)
Target weight: 3.00–3.60 lb (1,360–1,635 g). Cumulative feed consumption: approximately 4.00–4.60 lb (1,815–2,090 g) per bird. Growth rate is near its peak. Feed intake increases substantially. This is a critical period for monitoring ventilation and litter conditions as bird mass and metabolic heat production increase rapidly.
Week 5 (Days 28–35)
Target weight: 4.50–5.30 lb (2,040–2,405 g). Cumulative feed consumption: approximately 6.50–7.50 lb (2,950–3,400 g) per bird. Feed conversion efficiency begins to decline as birds approach market weight — each pound of gain requires more feed than in earlier weeks. Water consumption peaks during this period, especially in warm weather.
Week 6 (Days 35–42)
Target weight: 5.80–6.80 lb (2,630–3,085 g). Cumulative feed consumption: approximately 9.50–11.00 lb (4,310–4,990 g) per bird. Most conventional broilers are processed between 42–49 days. Final weight and FCR at this stage determine settlement value.
How to Sample Weights Accurately
Accurate weight sampling is essential for meaningful growth tracking. Weigh a minimum of 50–100 birds per house, sampled from multiple locations, to get a representative average. Use a calibrated scale. Weigh at the same time of day each week to avoid variation from fill levels. Record individual weights or total catch weight with bird count so averages can be calculated.
Weight variation within a house is as important as average weight. High variation (coefficient of variation above 10–12%) indicates uneven access to feed and water, inconsistent environmental conditions, or health problems affecting only part of the flock.
Connecting Growth Data to Decisions
Growth charts are most valuable when compared across flocks and connected to other data streams. When weight falls behind targets, check water consumption patterns from the same period, review mortality trends, examine feed delivery records to confirm adequate supply and correct formulation, verify temperature and ventilation settings, and compare performance across houses to see if the problem is house-specific or farm-wide.
Growers who track weight data consistently can identify their best-performing houses and replicate the conditions that produce strong growth. They can also identify chronic underperformers and decide whether those houses need equipment upgrades, ventilation improvements, or more intensive management attention.