When to Switch Chicks to Layer Feed: Feeding Chickens at Every Age
- Jan 7, 2025
- 5 min read
Updated: Jul 21
One of the most common questions new chicken owners ask is, "When should I switch my chicks from starter feed to layer feed?"
The simple answer is around 18 weeks of age, but understanding why chickens require different feed at different stages of life is just as important as knowing when to make the switch.
Commercial poultry feeds are carefully formulated to meet a chicken's changing nutritional needs. As chicks grow into pullets and eventually become laying hens, their requirements for protein, energy, vitamins, minerals, and calcium change significantly. Feeding the wrong diet at the wrong stage can affect growth, bone development, egg production, kidney health, and even a bird's lifespan.
In this guide, we'll explain what each type of poultry feed is designed for, why those formulations change as chickens mature, and how to ensure your flock receives the right nutrition at every stage of life.
Why Chickens Need Different Feed at Different Ages
Just as a growing child has different nutritional needs than an adult, chickens require different nutrients as they develop.
During their first few months of life, chicks grow at an incredible rate. They are developing muscles, bones, feathers, organs, and their immune system all at the same time. This rapid growth requires a diet that is higher in protein and carefully balanced in vitamins and minerals.
Once a pullet reaches maturity and begins producing eggs, her nutritional priorities change. Egg production places tremendous demands on her body, particularly for calcium, protein, and energy. Layer feed is specifically formulated to meet these new requirements.
Understanding these changing nutritional needs helps explain why each feed is designed for a particular stage of life—and why switching too early or too late can create health problems.
Starter Feed – Day 1 to 18 Weeks (Chicks)
Starter feed is designed to support the rapid growth that occurs during a chick's first few months of life.
It typically contains around 20% protein, the highest level a laying hen will consume during her lifetime. This extra protein supplies the amino acids needed to build muscle, feathers, organs, and a healthy immune system.
Starter feed is available in both medicated and non-medicated formulations and is nutritionally complete, meaning every bite provides the nutrients a growing chick requires.
Young chicks should remain on starter feed until approximately 18 weeks of age, unless your feed manufacturer recommends otherwise.
Medicated vs. Non-Medicated Starter Feed
One of the greatest health risks facing young chicks is coccidiosis, an intestinal disease caused by microscopic parasites that multiply in warm, damp environments contaminated with droppings.
Because young chicks have not yet developed immunity, coccidiosis can spread rapidly and become fatal if left untreated.
Medicated starter feed contains amprolium, which slows the reproduction of these parasites, allowing chicks time to develop their own natural immunity.
However, chicks that have received the coccidiosis vaccine should not be fed medicated starter feed, as amprolium interferes with the vaccine and reduces its effectiveness.
Whether using medicated or non-medicated feed, keeping brooders clean and dry remains one of the most effective ways to reduce the risk of coccidiosis.
Layer Feed – 18 Weeks
Around 18 weeks of age, pullets approach sexual maturity. Although many have not yet laid their first egg, their bodies are preparing for egg production. This is when their nutritional requirements begin to change, particularly their need for calcium.
Pullets should be transitioned to layer feed at around 18 weeks of age.
Layer feed must not be fed to chickens younger than 18 weeks unless they have begun laying eggs. Layer feed contains added calcium which, if fed too early, can permanently damage the kidneys, reduce lifetime egg production, and shorten a chicken’s lifespan.
Layer feed is available in mash, crumble, and pellets and typically contains 16–18% protein along with added calcium for strong bones and eggshell production.
If hens do not receive enough dietary calcium, they will pull calcium from their own bones to produce eggshells. Over time this can lead to weak bones and osteoporosis.
Supplemental Calcium
Layer feed contains crushed limestone, which provides a quick release of calcium.
Crushed oyster shell, which releases calcium slowly, should be offered free-choice in a separate dish rather than mixed with the feed. Each hen has different calcium needs and will consume the amount she requires.
Don’t be concerned if the oyster shell dish doesn’t seem to empty quickly. Hens that need extra calcium often take a piece or two before going to roost, since eggshell formation happens overnight.
During the day they receive calcium from their feed, but overnight—when they are not eating—some hens require additional calcium.
Oyster shell works somewhat like a rock in a dryer, tumbling in the gizzard and slowly dissolving overnight while the eggshell forms.
You can purchase oyster shell at most poultry feed stores.
Feeding Different Age Groups Together
“Chicken math” is real, and many backyard flocks end up with birds of different ages.
The best solution is to feed starter or grower feed and provide oyster shell free-choice in a separate dish.
The extra protein in starter or grower feed will not harm adult birds, but the extra calcium in layer feed can damage the kidneys of growing birds
Why We Do Not Feed Layer Mash
Commercial layer feeds are available in mash, crumble, and pellet forms. Although each contains the same nutrients when manufactured, the physical form of the feed can influence how chickens eat it.
Chickens naturally sort their feed by size, texture, and appearance. When offered mash, they often pick out the larger or more appealing particles while leaving behind the finer ingredients that contain important vitamins, minerals, and other nutrients.
Over time, this selective feeding can result in an unbalanced intake of nutrients, even though the feed was nutritionally complete when it left the mill.
Pellets provide a more consistent mouthful with every bite, making it much more difficult for chickens to selectively eat only their favourite ingredients. For this reason, we choose to feed layer pellets rather than mash.
Why We Do Not Feed Treats
Commercial poultry feed is designed to be a complete diet. Every pellet or crumble contains a carefully balanced combination of protein, amino acids, vitamins, minerals, energy, and other nutrients needed to support healthy growth, egg production, and overall flock health.
When treats such as scratch grains, cracked corn, mealworms, fruits, vegetables, or kitchen scraps replace even a small portion of that feed, the overall nutritional balance begins to change. While an occasional treat may seem harmless, daily treats can dilute the carefully formulated diet your chickens rely on each day.
This is why we do not feed treats to our chicks, pullets, or breeding flock. We believe the healthiest birds are those whose diet is built on a nutritionally complete poultry feed, allowing every bite to contribute to their long-term health and productivity.
Our Feed Choice
Our poultry feed of choice is:
• Purina Medicated Starter/Grower Crumbles for chicks and grow-outs
• Purina Layer Pellets for birds over 18 weeks
Purina poultry feed is produced by Land O’Lakes, not Nestlé (which makes Purina pet foods).
We choose Purina for two main reasons:
It is a well-established and respected feed company. Poultry nutrition is a science, not just a recipe, and long-standing companies invest heavily in research.
They have poultry nutritionists available if customers have questions about their feed—something few companies offer.
Looking for Purina feed? Contact your local feed mill or farm supply store to see which poultry feeds they carry. If you're located near Roslin Poultry Ranch, we're happy to recommend several local retailers.
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