If your chickens are eating but not reaching the body weight you expected, do not start by adding random supplements or “growth boosters.”
First work out what type of bird you are raising and what the correct growth target should be.
A broiler is raised for fast meat growth. A pullet is being prepared for future egg production. A cockerel grows more slowly and should not be judged by broiler standards.
The goal is not to make every chicken as heavy as possible. The goal is to help each type of bird reach the right body weight for its age and purpose.
Why are my chickens not gaining enough weight?
Poor weight gain usually comes from one or more of these areas:
- poor chick quality;
- low feed intake;
- poor feed quality;
- wrong feed for the bird or age;
- water problems;
- poor brooding;
- heat stress;
- crowding;
- too little feeder or drinker space;
- disease or parasites;
- uneven flock competition; or
- unrealistic weight expectations.
Start with the right target for the right bird
This is the first thing many farmers miss.
Broilers
Broilers are bred for rapid growth and efficient meat production.
Body weight should be compared with the target for the actual strain and age.
Pullets
Pullets should not be pushed to maximum weight.
The aim is steady growth, good frame development and good flock uniformity so the birds enter lay at the correct body weight.
Cockerels
Cockerels generally grow more slowly than commercial broilers.
If you compare them with a modern broiler growth chart, they may look “slow” even when they are growing normally for their type.
Weigh the birds before changing anything
Do not diagnose poor growth by looking at the flock from a distance.
Take a sample of birds and weigh them.
Record:
- age;
- average body weight;
- range of weights;
- feed intake;
- mortality;
- major disease events; and
- recent feed changes.
For broilers, compare with the current breeder performance guide for the strain.
For pullets, compare with the breeder body weight target and uniformity target.
Check whether all birds are small or only some
This helps narrow the problem quickly.
If almost all birds are underweight, look first at:
- feed quality;
- feed intake;
- water;
- brooding;
- heat;
- disease affecting the flock; and
- wrong feed specification.
If only some birds are small, look at:
- feeder competition;
- drinker access;
- chick quality;
- early brooding problems;
- disease affecting part of the flock; and
- flock uniformity.
Check feed intake before blaming the feed formula
A good feed cannot work if the birds are not eating enough of it.
Measure how much feed goes into the house and how much is left.
Low feed intake can come from:
- heat stress;
- dirty or stale feed;
- poor pellet or mash quality;
- too little feeder space;
- empty feeders;
- poor lighting;
- disease;
- water problems; or
- sudden feed changes.
For poultry feed troubleshooting, see our How Do I Know If the Feed I Bought Is Working? guide.
Check water before adding supplements
Water problems can reduce growth very quickly.
Check:
- tank level;
- blocked drinkers;
- water pressure;
- drinker height;
- leaks;
- water cleanliness; and
- whether all birds can reach water.
If birds are thirsty, feed intake usually suffers too.
Use the right feed for the bird and stage
Starter, grower and finisher feeds are not just different names on bags.
They are designed for different stages.
But the exact age for changing feed should come from the breeder or feed programme being used.
Do not assume every broiler should change feed on the same day.
Do not assume every pullet should follow a broiler feeding programme.
For the basics, see our Poultry Nutrition Guide.
Do not judge feed by crude protein alone
A feed can have a good crude protein percentage and still perform badly.
Growth also depends on:
- energy;
- amino acids;
- feed intake;
- ingredient quality;
- fibre;
- minerals;
- vitamins; and
- digestibility.
For ingredient quality, use our Livestock Feed Ingredients Guide.
Brooding problems can follow the flock for weeks
Poor first week management can reduce later growth.
Check whether chicks had:
- correct floor and air temperature;
- easy feed access;
- easy water access;
- good crop fill;
- dry litter;
- fresh air without chilling; and
- low early mortality.
A flock that started badly may remain uneven even after the brooder problem is corrected.
See our Broiler Chick Brooding Guide.
Heat stress reduces growth
When chickens are too hot, they often eat less.
Less feed means fewer nutrients available for growth.
Watch for:
- panting;
- wings held away from the body;
- crowding near drinkers;
- reduced feed intake; and
- birds spreading out to cooler areas.
Improve airflow, water access, shade and feeding management before blaming the feed.
See our Heat Stress in Poultry Guide.
Check stocking pressure and space
Too many birds in one space can reduce access to feed and water and increase heat and litter problems.
Do not use one fixed stocking number for every house.
Space needs depend on:
- bird size;
- age;
- house design;
- ventilation;
- climate; and
- production system.
Use our Floor Space Requirements Guide for practical planning.
Feeder space matters more than feeder count
Adding more feeders does not automatically make birds gain more weight.
The real question is whether all birds can reach feed without too much competition.
Check:
- feeder height;
- feeder space;
- feed depth;
- whether feed is available at the right times; and
- whether smaller birds are being pushed away.
Lighting should support feeding and rest
Light helps birds find feed and water.
But more light does not automatically mean more growth.
Commercial broilers also need rest periods.
Follow the breeder lighting programme and local welfare guidance rather than keeping lights on continuously just to force feed intake.
Disease can reduce weight before other signs become obvious
When birds are not gaining weight, watch for:
- changes in droppings;
- coughing or sneezing;
- poor feathering;
- hunched posture;
- reduced appetite;
- wet litter;
- pale combs;
- uneven growth; and
- rising mortality.
Do not respond to poor growth by giving antibiotics automatically.
First identify the likely cause.
See our Signs of a Sick Chicken Guide.
Parasites can also affect growth
Internal and external parasites can reduce performance, but do not deworm blindly on a fixed calendar without considering actual risk and diagnosis.
If worms are suspected, see our Worms in Chickens Guide.
Do not use growth boosters as the first answer
If birds are underweight, fix the basics first:
- feed;
- water;
- brooding;
- heat;
- space;
- disease;
- feed access; and
- management.
Vitamins, amino acids, probiotics or other additives may have a place in a properly designed feeding programme, but they do not correct every cause of poor growth.
Antibiotics should not be used simply as growth boosters.
Do not add extra protein blindly
A common response to slow growth is to add more soybean meal, fish meal or protein concentrate.
That can make the ration more expensive and may unbalance it.
If the feed is already complete, random additions can reduce the balance of energy, amino acids, minerals and other nutrients.
Do not starve birds to save feed
Underfeeding can reduce growth, damage uniformity and increase competition.
For broilers especially, cutting feed just to reduce cost can become more expensive if market weight is delayed.
Use our If I Reduce My Birds’ Feed, What Will Happen? guide for the economics and performance effect.
Sorting can help, but do it for the right reason
Sorting very uneven birds can help smaller birds get better access to feed and water.
But sorting should not be used as a substitute for fixing the cause of uneven growth.
If you keep seeing many small birds, investigate:
- early chick quality;
- brooding;
- feeder access;
- disease;
- heat;
- feed quality; and
- stocking pressure.
For pullets, heavier is not always better
This is important.
Pullets are future laying hens.
The aim is not to make them as heavy as broilers.
They should follow the body weight target for the layer strain and maintain good uniformity.
Too much body weight before lay can create later production problems.
Use our Layer Nutrition Guide for stage specific feeding.
For cockerels, use realistic expectations
Cockerels do not usually match commercial broiler growth.
If market size is the goal, track your own flock growth and feed cost instead of comparing them with broiler targets.
The important question is whether the birds are growing steadily and profitably for your market.
Track feed conversion where it is useful
For broilers, feed conversion ratio can help show whether birds are turning feed into body weight efficiently.
But FCR should not be judged without considering:
- mortality;
- feed wastage;
- temperature;
- disease;
- market age; and
- the weight of the birds.
Use records instead of memory
Record:
- weekly body weight;
- feed used;
- water intake where practical;
- mortality;
- medications and vaccines;
- feed batch or supplier;
- weather problems; and
- major management changes.
Without records, it is difficult to know whether a change actually improved growth.
Simple poor growth checklist
- Correct bird type and target confirmed.
- Birds weighed.
- Feed intake checked.
- Water system checked.
- Feed stage correct.
- Feed quality checked.
- Brooding history reviewed.
- Heat stress checked.
- Stocking pressure checked.
- Feeder and drinker access checked.
- Disease and parasites considered.
- Records compared with previous weeks.
Bottom line
When chickens are not gaining enough weight, do not start with boosters.
Start with the bird type, target body weight, feed intake, water, feed quality, brooding, heat, space and health.
Then fix the actual problem.
Broilers need efficient growth. Pullets need controlled development. Cockerels need realistic targets. Good weight management starts by knowing the difference.
If your main problem is broilers that are not growing, use our Broilers Not Growing Troubleshooting Guide for a deeper check.
