Broiler Weight by Age

A Ross 308 broiler weighs about 213 g at day seven, 1,012 g at day twenty one, 2,296 g at day thirty five and 2,998 g at day forty two, sexes mixed. A Cobb 500 runs heavier at the end, near 3,278 g by day forty two. Both figures are breeder performance objectives measured under controlled conditions. Ugandan flocks routinely land well under them, and Uganda's own ministry tables show it.

Broiler Weight by Age: The Breed Standard Tables

Two companies breed most of the broilers in the world and both publish weight targets for their own birds. Aviagen publishes performance objectives for the Ross 308, Cobb Vantress for the Cobb 500. These are the numbers a weekly weighing is meant to be measured against, and they are the only weight figures on this page that come with a stated method and a stated set of conditions.

Both columns are the as hatched figures, meaning cockerels and pullets mixed as they come, which is what a Ugandan farm actually buys. The last column is cumulative feed conversion for the Ross bird, feed eaten per kilogram of live weight, and it is in the table because a weight without its feed cost attached tells you only half of what you need.

Notice what the two columns do. Ross leads at day seven and Cobb has overtaken it by day fourteen, then stays ahead to the end, reaching day forty two about 280 g heavier. Whichever bird you have, comparing it against the other breeder's chart will make it look either better or worse than it is.

What the Broiler Breed Standards Assume, and Who Publishes Them

These are legitimate published standards and they should be used, but they need reading with their conditions attached, because the companies themselves attach them.

Aviagen states its own conditions plainly in the front of the document: the objectives indicate performance achievable under good management and environmental conditions when feeding recommended nutrient levels, producers may find local factors prevent it, the availability of raw materials may limit nutrient content and intake, extreme climatic conditions will reduce performance, and average performance may be lower than the figures presented. Cobb's version is one line: broiler performance varies from country to country.

Read as targets, those figures are the most useful thing on a Ugandan broiler farm, because they tell you the direction and the shape of the curve. Read as predictions, they will make a competently run Ugandan flock look like a failure.

What Ugandan Broiler Flocks Actually Weigh

Uganda's Ministry of Agriculture, Animal Industry and Fisheries publishes its own broiler weight figures, and the interesting thing is that a ministry with no commercial interest in flattering the bird reports considerably lower weights than the companies selling it.

The last column is the mash that produced each week's weight, per bird, from the ministry's own per hundred bird figures. It totals about 4.2 kg to reach 2,000 g at week six, a whole cycle conversion near 2.1.

Now put the two sets side by side at the same age. At day forty two the breeder target is 2,998 g on a Ross bird; the ministry's mash fed figure is 2,000 g. That is a third lighter. At day thirty five the target is 2,296 g and the ministry gives 1,750 g on pellets or 1,600 g on mash. And the conversion gap is wider still: 1.53 against about 2.1, meaning the Ugandan bird ate considerably more feed for its smaller weight.

Both sets are published and neither is wrong. They describe different things. One is what the genetics can do in a controlled house on a formulated ration; the other is what a Ugandan extension service expects a farmer to get. If your flock sits between them you are doing normally well. If it sits at or above the ministry line and climbing toward the breeder line, you are doing better than most.

Why the Gap Between the Breed Standard and a Ugandan Broiler Flock

The genetics in a Ugandan broiler house are the same genetics that produce the breeder charts, since the chicks descend from the same parent stock. So the gap is not about the bird. It is about four things the bird needs and often does not get, in roughly this order of impact.

Feed that carries the protein and energy it claims. Brooding heat in week one. Space and water that keep pace with the flock as it grows. And a flock healthy enough to eat. Each gets a section below, because knowing which one is costing you weight is the whole point of weighing in the first place.

One thing worth saying about the shape of the gap rather than its size. It does not open at the end, it opens at the start. A chick that is 30 g light at day seven is not 30 g light at day forty two, it is several hundred grams light, because everything after week one compounds on a smaller frame. Which is why the seven day weight is the earliest and cheapest diagnostic a broiler farm has: the breeder target is 213 g on a Ross and 202 g on a Cobb, roughly five times hatch weight, and you know on day seven whether you are near it.

Feed Quality and Broiler Weight Gain

A bird cannot exceed what is in the bag. The breeder charts assume a ration formulated to the company's own nutrient specification, and a Ugandan bag labelled broiler starter may or may not be near it, since millers compound to their own recipes and a farmer cannot test protein at the counter.

There is also a documented reason a correctly formulated bag can still produce a light flock. Aflatoxin, produced by moulds on badly dried or damply stored cereals, cuts body weight gain and raises feed conversion in broilers at levels found in ordinary poultry feed, and Ugandan maize and maize bran are documented carriers. It does its work without any visible signal in the birds until the scale tells you.

The practical version: a flock tracking its breed curve is being fed adequately whatever the bag claims, and a flock falling away from the curve on the right quantities of feed at the right temperature and density is telling you about the feed. That is the diagnostic value of weighing, and it is why weight and feed have to be read together rather than separately. The whole feeding programme is on the broiler feeding guide.

Brooding Temperature Sets the Weight Curve in Week One

A cold chick does two things: it burns feed energy on staying warm rather than growing, and it moves less, so it eats less. Both come straight off the seven day weight and neither is recoverable inside a six week cycle.

MAAIF's brooder specification runs from about 34 degrees Celsius at the start down to about 28 by the end of brooding, stepping down roughly a degree every three days. The check that actually predicts the seven day weight, though, is the crop fill test: the morning after placement, at least 95 percent of chicks should have soft, filled crops. A flock that fails that test on day one has already lost weight it will not get back, and you know about it a week before the scale would have told you.

Hard crops mean they found feed and not water. Slack, swollen crops mean water and not enough feed. Both produce a light seven day weight through different routes, and both are fixable on day one. The full brooding method sits on the poultry brooding guide and in the housing section of the broiler farming guide.

Stocking Density, Water Access and Growth to Market Weight

Overcrowding costs weight through competition. Birds at the back of a crowded house eat less, the litter wets, ammonia rises, and the flock average falls while its variation widens, which is the tell: a crowded flock is not uniformly light, it is uneven. MAAIF's broiler densities step from 30 to 40 birds per square metre in the brooder to 25 after brooding and 10 at five to six weeks, and a house left at brooding density is the commonest reason a flock stops tracking its curve in week four.

Water is the faster and less obvious one. A bird that cannot drink stops eating within hours, so any restriction on water is a restriction on weight. MAAIF puts normal water intake at about 1.6 to 1.8 times feed intake at temperatures up to 25 degrees Celsius, which means drinker capacity has to grow every week alongside feed. Drinkers that were ample in week two are a queue by week five, and the flock average records it.

Ross Against Cobb: Does the Broiler Breed Change Your Weight Target

Yes, and by enough to matter. At day forty two the published targets are 2,998 g for the Ross 308 and 3,278 g for the Cobb 500, a difference of about 280 g, or nearly 10 percent. Judge a Cobb flock against the Ross chart and it looks like it is doing better than it is. Judge a Ross flock against the Cobb chart and a perfectly good flock looks like a failure.

The crossover is worth knowing too, because it affects how you read an early weighing. The Ross target is slightly ahead at day seven, 213 g against 202 g, and the Cobb target is ahead from day fourteen onward. So a Cobb flock that looks marginally behind at the first weighing may be exactly on its own curve.

Which is a long way of saying: ask what strain your chicks are when you order them, and get the chart for that strain. Ugandan hatcheries and importers supply both lines, and chick suppliers will tell you which they are selling if you ask. Neither bird is better; they are different targets.

Cockerels Weigh More Than Pullets, and the Gap Widens

The as hatched figure everyone quotes is an average of two quite different birds. Aviagen publishes separate objectives for each sex, and the divergence is small at first and large by market.

At day seven the two sexes are the same weight. By day forty two the cockerel target is about 450 g above the pullet target, roughly 16 percent. That has two consequences on a Ugandan farm. A flock average is an average of two populations, so a wide spread at weighing may be sex rather than a management problem, and you can tell the two apart by looking at whether the light birds are all one sex. And where a buyer wants a particular bird size, the cockerels reach it days before the pullets do, which is an argument for selling in two passes rather than one.

How to Weigh a Broiler Flock Properly

Most Ugandan broiler farms do not weigh at all, and of those that do, many weigh the wrong birds. MAAIF's instruction is specific: weigh weekly, take 10 percent of the birds from the four corners of the house, average them, and benchmark that average against the standard for the breed.

The seven day weighing is the one to start with if you are only going to do a few. It is the earliest point at which the flock can be diagnosed and the point at which something can still be done.

Reading an Underweight Broiler Flock

A light flock is a symptom. The useful question is which of five or six causes it is, and the shape of the weight data narrows it down before you spend money.

Two causes are invisible in the flock and visible only in the numbers. Aflatoxin in feed slows gain with no outward sign. And a failed vaccination shows up as disease later in the cycle rather than as anything at the time, which matters because Ugandan broiler flocks fail vaccination far more often than farmers realise. Both are covered elsewhere, on the vaccination schedule and the mortality pages.

Which Week to Sell: Weight Against Feed Already Eaten

The last thing a weight chart is for is deciding when to stop. Look again at the Ross cumulative conversion column: 1.27 at day twenty eight, 1.40 at day thirty five, 1.53 at day forty two, 1.66 at day forty nine. Every week the whole cycle figure gets worse, because the feed the bird eats that week buys less weight than the week before.

So a heavier bird is not automatically a more profitable bird. Past target weight the flock keeps gaining and keeps costing more per kilogram gained, and whether that trade works depends entirely on how your buyer pays. A trader buying live birds by weight pays for every extra gram. A restaurant buying by the bird at a fixed size pays nothing for the extra, and may reject a bird that has outgrown its portions.

Which means the sell decision is a buyer question answered with weight data, not a weight question. Know the size your buyer wants, read your own weekly average against the breed curve, and sell in the first week the flock reaches it. The chicken price page and the cost of raising 100 broilers page carry the money side.

Broiler Weight Questions Ugandan Farmers Ask

What should a broiler weigh at 6 weeks in Uganda? The breeder target at day forty two is 2,998 g for a Ross 308 and 3,278 g for a Cobb 500, sexes mixed, under controlled conditions. MAAIF's own figure for a mash fed Ugandan broiler at week six is 2,000 g. A well run Ugandan flock lands somewhere in that band. Below the ministry figure, work through the diagnostic above.

Why are my broilers not reaching 2 kg at 6 weeks? In order of likelihood: the feed is not what the label says, brooding was too cold in week one, the house was never destocked to 25 and then 10 birds per square metre, drinker capacity stopped keeping up, or the flock had a health challenge that cost it a week. The weight pattern tells you which, if you kept a weekly record. Without a record, you are guessing.

What is a good 7 day weight for broilers? The published targets are 213 g for a Ross 308 and 202 g for a Cobb 500, about five times hatch weight. It is the most useful single figure on a broiler farm because it is early enough to act on and it predicts the rest of the curve.

How much do broilers weigh at 8 weeks? Ugandan flocks commonly run to week eight, but published figures past day forty nine are for genetics managed under controlled conditions and do not transfer well. The Ross objective reaches 3,681 g at day forty nine. What matters more at week eight is that conversion has deteriorated to about 1.66 on the breeder chart and well past 3 kg of feed per kilogram of gain on a Ugandan mash routine, so the extra weight is the most expensive weight of the cycle.

Do cockerels and pullets need separate weight targets? If you are weighing a mixed flock, use the as hatched column. If your chicks were sexed, use the relevant column: the cockerel and pullet targets diverge from day fourteen and are about 450 g apart by day forty two.

What does a broiler weigh dressed, compared with live? No dressing percentage is given here, because it depends on the bird's age, its fat, and how the carcass is cut and chilled, and both breeding companies say their own yield figures vary between processing plants for exactly those reasons. Ask your buyer what they measure and weigh a few birds both ways on your own farm before you agree a price basis.

Does feeding pellets make broilers heavier? Not heavier at the same age; heavier sooner. MAAIF's pellet table reaches 1,750 g by week five where its mash table needs into week six for 2,000 g, and it does it on considerably less feed. Whether that pays is a bag price question rather than a weight question, and the poultry feed price page has the moving figure.

Can I use these charts for Kuroilers or local chickens? No. These are meat strain targets and a dual purpose or indigenous bird grows on a completely different curve over months rather than weeks. The Kuroiler weight by age page carries the measured Ugandan figures for that bird, and Kuroiler against broilers works through the choice.

Ask your supplier which strain your chicks are before you order, and get the breeder chart for that strain so your weekly weighing has something honest to measure against. The poultry hub holds the rest of the broiler pages, the farm weighing scales page covers what to weigh with, and the feed requirement calculation turns a weight target into a bag count.