Weighing broilers: how many birds, how often
Sample sizes, weekly timing and reading uniformity, so you know how a flock is growing without a scale in every pen.
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Why weigh at all
A broiler flock is sold by weight, so growth is the whole business. You can't see a 10% shortfall by looking at birds, but you will feel it at the sale. Regular weighing tells you early whether the flock is on track for your target weight and day, and gives you time to fix feed, water, heat or space before it's too late.
How many birds to weigh
You don't need to weigh every bird. A fair sample gives you a reliable average:
- Weigh at least 50 birds per house, and up to 100 in a large house.
- Take them from at least three spots: near the front, the middle and the back, and from both sides.
- Weigh every bird you catch in a spot, not just the ones that are easy to grab. Picking birds by hand favours the big, slow ones and makes the flock look heavier than it is.
A small catching frame or a corner pen helps: herd a group in, then weigh all of them one by one.
How often, and when
Weigh once a week, on the same day and at the same time. Weights change through the day as birds eat and drink, so comparing a morning weighing with an afternoon one tells you about the time of day, not about growth.
Write each bird's weight down individually, in grams. A single group weight gives you the average but hides how even the flock is.
Reading the numbers
Three figures come out of one weighing:
Average weight
Total of all weights ÷ number of birds weighed
Compare it with your breed's target for the flock's age in days.
- Uniformity: the share of birds within 10% of the average. If the average is 1,500 g, count the birds between 1,350 g and 1,650 g. A higher share means a more even flock.
- Coefficient of variation (CV): the spread of the weights as a percentage of the average. A lower CV means a more even flock.
A flock can hit its average while being uneven: some birds well ahead, many behind. Poor uniformity usually points to competition at feeders and drinkers, uneven heat, or birds placed at different weights.
When the weights fall behind
If the average is below target for the age, check:
- Feeder and drinker space: enough for every bird to eat at once, at the right height.
- Water: flow rate and cleanliness. Birds that don't drink don't eat.
- Temperature: chicks that are cold huddle instead of eating; birds that are hot eat less.
- Feed: the right ration for the age, and fresh.
In OrnisNest, you record each bird's weight in grams. The average, uniformity and CV are worked out for you, and a weighing comes due every week for each flock.