Broiler Growth & Hit the Breed Standard

A broiler growth standard is the published table of expected body weight, daily and cumulative feed intake, and feed-conversion ratio (FCR) at each age for a particular breed — like Cobb 500 or Ross 308. The breeding company derives it from large managed trials, so it represents the genetic potential of the bird under good conditions. It's the benchmark you compare your real flock against.

Weigh a sample of your flock at a given age and compare the average to the standard target weight for that age and breed. Hitting the target means feed, health and management are on track. Falling well below it flags a problem — poor feed, disease, heat stress, crowding or water issues — early enough to fix before it costs you at sale.

Cumulative feed to a given age is the target body weight multiplied by the cumulative feed-conversion ratio to that point: feed = target weight × FCR to date. So a bird at a 2.0 kg target with an FCR of 1.6 has eaten about 3.2 kg of feed cumulatively. This lets you budget feed and check that your flock's actual consumption matches the standard.

Feed-conversion ratio (FCR) is the kilograms of feed eaten per kilogram of live weight gained — lower is better. Modern broilers run cumulative FCRs around 1.4–1.7 by market age. FCR is the single biggest driver of broiler profit because feed is the largest cost, so tracking it against the standard tells you how efficiently your birds are converting feed to meat.

Cobb and Ross are the two dominant commercial broiler genetics worldwide, each with their own performance standards (e.g. Cobb 500, Ross 308). Their target weights and FCR curves are similar but not identical, so always compare your flock to the standard for the exact breed you're running — using the wrong chart gives misleading benchmarks.

Comparing weekly turns the standard into an early-warning system. A flock that tracks the curve and then suddenly flattens points to a recent event — a feed change, vaccination reaction, ventilation fault or disease. Catching that gap in week three is far cheaper to fix than discovering an underweight, inefficient flock at slaughter.

Yes — published standards reflect well-managed birds with good feed, climate, biosecurity and density. Real flocks often run a little under, especially in hot climates or with lower-spec feed. Use the standard as the goal and the comparison gap as your management score; the aim is to close the gap, not to expect a perfect match.

Yes — enter any age within the growing period and the calculator returns the standard target weight, cumulative feed and FCR to that point for the chosen breed. That lets you set interim weighing targets at days 7, 14, 21, 28 and 35, which is how good broiler managers keep a flock on track rather than checking only at the end.

They're solid breed benchmarks. Actual results vary with feed quality, climate, health, density and management, and breeders update their standards over time. Treat the numbers as a planning and comparison guide, weigh real samples regularly, and use the gap to steer — broiler management is about closing on the standard, not exact prediction.