Best Practices for Growing Laying-Type Birds: From 9 to 20 Weeks

The period between 9 and 20 weeks is one of the most critical windows in a pullet’s life. By week 9, the rapid organ and skeletal development of early chick growth is largely complete, and the bird shifts its energy toward muscle development, reproductive tract maturation, and building the body composition it will carry into the laying house. Get this phase right, and you set the stage for a productive, profitable flock. Get it wrong – through poor feeding, overcrowding, or neglected health management – and the damage carries through to the entire laying period. Here’s what good grower management looks like, and why each practice matters.

Understanding the grower phase (weeks 9-20) 🔗

After the brooding and starter phase, pullets enter what is commonly called the growing or rearing phase. From week 7 to week 15, the growth rate begins to slow, and by 12 weeks the skeleton is almost completely developed. The final stage – from about 15 to 20 weeks – is defined by ovary development, rapid growth of the reproductive tract, and the onset of sexual hormonal regulation. Twelve-week body weights are reliable predictors of 20-week weights, meaning pullets that are underweight at 12 weeks will still be underweight when it’s time to transfer to the laying house. This makes consistent weekly weight monitoring non-negotiable.

The overall goal during this phase is not just weight gain, but achieving the right body composition – adequate muscle, a well-developed skeletal frame, and controlled fat levels. Flock uniformity, as it relates to body weight and size, is the most important management goal during the growing phase, because non-uniform flocks produce inconsistent laying results, with slow onset of production and reduced peak output.

Space requirements: why 900 cm² per bird matters 🔗

Floor space during the growing phase directly affects flock health and uniformity. The standard recommendation for growing pullets on deep litter floor systems is 900 cm² per bird (approximately 0.09 m²). Adequate density ensures every bird has equal access to feeders and drinkers – a practical prerequisite for weight uniformity. Ensuring adequate stocking density is an important pullet management strategy, as is providing a clean, healthy environment and fresh drinking water. When birds are overcrowded, competition at feeders results in dominant birds eating more while lighter birds fall further behind, compounding uniformity problems that are extremely difficult to reverse after 16 weeks.

Feeder space should be increased to 3 to 4 inches per growing pullet from 8 weeks of age onwards. For water, provide at least 40 inches of watering space per 100 birds, or 1 gallon of capacity per 10 birds if using fountain-style waterers. Waterers should be checked daily – uneven distribution of water access leads directly to reduced feed intake and slower growth.

Feed management: the case for controlled feeding 🔗

Nutrition strategy during the growing phase is probably the single most consequential management decision a producer makes. The key question is whether to feed ad libitum (free choice) or apply some degree of feed restriction. For egg-type pullets, the evidence firmly supports controlled or restricted feeding from the growing phase onward.

Why unrestricted feeding is a problem 🔗

When growing pullets are allowed to eat freely, they tend to consume excess energy, which gets stored as abdominal fat. Excessive accumulation of abdominal fat in pullets may adversely affect egg production during the laying phase by disrupting reproductive function and making it harder for birds to meet target body weights at sexual maturity. Research on restricted feeding has shown that hens given controlled rations demonstrated improved egg production and less abnormal ovarian morphology compared to those fed without restriction.

Additionally, a pullet that grows too fast gains too much fat by the time she starts to lay, resulting in fewer and smaller eggs, and a higher tendency for laying problems such as egg binding or prolapse.

How feed restriction works in practice 🔗

The grower diet for birds aged 9-20 weeks is formulated with reduced protein and energy compared to the starter ration. A 14%-16% pullet developer ration with reduced energy content means pullets will eat more volume of feed, which increases their digestive capacity – an important benefit heading into the demands of the laying period. The reduced energy also limits fat accumulation without compromising muscle or skeletal development.

Feed can be given in two daily allocations, with appropriate quantities adjusted by body weight targets rather than strictly by age. Supplying feed twice a day – approximately one-third in the morning and two-thirds in the afternoon – stimulates feed intake, ensures that fine feed particles are consumed, and prevents mold accumulation. Feeders should be emptied briefly to confirm birds are actively consuming their allocation, but prolonged feed deprivation is counterproductive and stressful.

Feed restriction also delivers a direct cost benefit. Feed typically accounts for 60-70% of the total cost of poultry production. Controlling intake during the growing phase reduces total feed consumed per bird from 9 to 20 weeks without sacrificing laying performance – and in many cases, it improves it. Pullet growers must manage their flocks so that birds are in proper condition at key stages of sexual maturity if a profitable laying flock is to be achieved.

Pre-lay feed transition 🔗

From around week 17-18, birds should transition to a pre-layer diet before full layer feed begins. Pre-layer feed is a must and should be offered 2-3 weeks before egg production, when the liver and reproductive organs are increasing in size and calcium reserves are being built up for shell production. Jumping straight from grower to layer feed without this intermediate step can cause digestive upset and reduce early laying performance. Importantly, growing chickens require only about 1.2% calcium in their feed, while layer feeds contain 2.5% to 3.5% – feeding high-calcium diets to growing birds can cause kidney damage.

Beak trimming: preventing pecking and feed wastage 🔗

Beak trimming (also called beak conditioning) is a standard practice in commercial pullet rearing and serves two important functions: reducing feather pecking and cannibalism, and minimizing feed wastage at the trough.

Pecking behaviors can escalate rapidly in growing flocks, particularly when birds are housed at higher densities or experience nutritional deficiencies, bright lighting, or boredom. Recent scientific studies have shown that when hens who do not know each other first meet in the barn, they explore their flock mates by pecking – behavior referred to as exploratory pecking, which forms part of the natural repertoire of fowls. In a densely housed growing flock, this exploratory behavior can turn injurious if beaks are not managed.

Beak trimming is most commonly performed at the hatchery (day 1) using an infrared beak treatment system, but may need to be repeated – or performed for the first time – at around 8-10 weeks of age if not done earlier. Beaks should be retrimmed as necessary at the time of transfer to the laying house. Properly trimmed beaks also reduce the amount of feed birds can scoop out of troughs and scatter, directly reducing daily feed wastage – a meaningful saving over a 12-week growing period across hundreds or thousands of birds.

Water requirements during the growing phase 🔗

Water is often the most overlooked nutrient in poultry management. During weeks 9-20, growing birds need continuous access to clean, fresh water at appropriate temperatures. General guidance calls for at least 1 liter of water per 10 birds at all times, with drinker height adjusted regularly as birds grow. Nipple drinkers and cup systems should be inspected daily for blockages or pressure inconsistencies. A reduction in water intake is one of the earliest indicators of illness, heat stress, or management problems – tracking water consumption daily is a simple but effective health monitoring tool.

In warm climates, water consumption rises significantly. Feed intake decreases not only when temperatures rise, but also when dietary energy is increased – so in hot environments, water access becomes even more critical to compensate for reduced voluntary feed intake.

Deworming during the growing phase 🔗

Internal parasites – particularly roundworms (Ascaridia galli), cecal worms, and tapeworms – are a significant but often underappreciated challenge in pullet rearing, especially in litter-floor housing systems. Worm burdens accumulate during the growing phase as birds peck at litter and feces, and if left unchecked, they compete with the bird for nutrients, impair gut health, and reduce body weight gain. A common recommendation is to deworm at week 6 and again at week 14, though the schedule should be adapted to local parasite pressure and housing type. Effective dewormers for poultry include piperazine (for roundworms) and fenbendazole (broad-spectrum). Rotation of deworming agents reduces the risk of resistance developing.

Vaccination schedule from 9 to 20 weeks 🔗

The immune system is still being trained and reinforced throughout the growing phase. Vaccines administered during weeks 9-20 build on the foundation laid during brooding and provide the protection birds will need once they reach the high-stress laying period. Any vaccination program must be designed according to the prevalence of diseases in the region and the specific history of the target farm – but two diseases deserve particular attention during this phase: Infectious Coryza and Newcastle Disease (RD).

Infectious Coryza 🔗

Infectious Coryza, caused by Avibacterium paragallinarum, is a bacterial respiratory disease characterized by nasal discharge, facial swelling, and a significant drop in egg production. It is most problematic in laying-age birds, making the growing phase the right time to vaccinate before production begins. Vaccination on individual farms should be completed between 10 and 20 weeks of age, with layers receiving two injections approximately 4 weeks apart for adequate protection before they turn 20 weeks old. Because serovars A, B, and C of A. paragallinarum are not cross-protective, the bacterin used must contain the serovars present in the local bird population.

Newcastle Disease (Ranikhet Disease) 🔗

Newcastle Disease (ND), known as Ranikhet Disease (RD) in South Asia, is a highly contagious viral disease affecting the respiratory, nervous, and digestive systems. It can cause up to 100% mortality in unvaccinated flocks. For breeder and layer chicken flocks, the Newcastle vaccine needs to be repeated at 3-month intervals to maintain sufficient immunity levels. During the growing phase, a booster of the LaSota (live) vaccine via drinking water is typically given at around weeks 12-14, followed by an oil-emulsion killed vaccine injection at 16-18 weeks before transfer to the laying house – combining live and killed vaccines provides both mucosal and systemic immunity.

Other vaccines to consider 🔗

At weeks 10-12, Infectious Coryza and Egg Drop Syndrome (EDS) vaccines are also given, as Coryza causes facial swelling, nasal discharge, and a drop in egg production. Fowl pox vaccination is typically administered at 10-12 weeks via the wing-web stab method, particularly in tropical and subtropical regions where the virus spreads via mosquito bites. Any vaccination given in the last 2 weeks before transfer to the laying house should be completed at least one week before the move to allow immune response to develop without the added stress of relocation.

Lighting management during the growing phase 🔗

Light plays a critical role in controlling the timing of sexual maturity. During the growing phase (weeks 8-18), a step-down or constant short-day lighting program is used to deliberately delay sexual maturity until the bird has reached optimal body weight and frame development. In a typical step-down lighting program, the hours of light are gradually decreased over the first 8-12 weeks, providing growing pullets additional feeding time to promote growth. Stimulating pullets with increasing daylength before they are physically ready results in small eggs at the start of lay, poor peak production, and more laying problems – benefits that are hard to recover once the laying cycle begins.

Preparing for the transfer at 20 weeks 🔗

The growing phase ends when pullets approach sexual maturity at around 18-20 weeks, at which point they are transferred to the laying house. Pullets should be moved to the laying housing around 2-4 weeks before they start laying – closer to 3 or 4 weeks pre-lay is ideal, as this gives birds more time to recover from the stress of moving and adjust to their new environment. Conditions in the growing house – temperature, lighting, feeder type – should gradually be aligned with those in the laying house in the final two weeks to reduce the magnitude of the transition stress.

At the time of transfer, perform a final flock assessment: verify body weight uniformity, check beak condition, ensure all scheduled vaccines have been completed, and cull any birds that are visibly unthrifty or underweight. Any vaccinations should be given at least a week before the transfer to ensure a prompt immune response without additional stress. A well-managed growing phase means birds arrive at the laying house on weight, uniform, healthy, and ready to perform.

What do you think? Given that feed restriction during the growing phase can both reduce costs and improve laying performance, why do you think many small-scale poultry producers still default to unrestricted feeding – and what practical changes would make controlled feeding more accessible for them? Also, considering how critical weeks 9-20 are for immune development, how should a producer prioritize their vaccination schedule if resources are limited and they can only protect against one or two diseases during this window?

References

1. https://layinghens.hendrix-genetics.com/en/articles/preparing-long-life-layer/
2. https://lohmann-breeders.com/lohmanninfo/management-of-pullets-and-laying-hens-under-tropical-conditions/
3. https://www.premix.adm.com/blog/pullet-management-how-to-set-them-up-for-success/
4. https://extension.umn.edu/small-scale-poultry/raising-layer-chicks-and-pullets
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC11917390/
6. https://pubmed.ncbi.nlm.nih.gov/25458320/
7. https://www.cacklehatchery.com/how-to-feed-pullets-for-optimal-egg-production/
8. https://www.poultrysite.com/articles/importance-of-pullet-feeding-programs-in-ensuring-a-profitable-laying-flock
9. https://poultry.extension.org/articles/feeds-and-feeding-of-poultry/feeding-chickens-for-egg-production/
10. https://lohmann-breeders.com/lohmanninfo/management-recommendations-for-rearing-pullets-for-alternative-housing-systems/
11. https://www.merckvetmanual.com/poultry/nutrition-and-management-poultry/management-of-laying-chickens
12. https://www.livestocking.net/vaccination-schedule-for-layers-poultry-birds
13. https://www.merckvetmanual.com/poultry/infectious-coryza/infectious-coryza
14. https://eorganic.org/pages/70026/poultry-vaccines-for-use-on-organic-farms
15. https://www.bivatec.com/blog/standard-vaccination-schedule-for-broilers-and-layers
16. https://www.hyline.com/Upload/Resources/TU%20PULLET%20MGMT%20ENG.pdf
17. https://extension.psu.edu/preparing-pullets-what-to-expect-for-the-transition-to-lay