Layer Feed vs Starter vs Grower: What to Use When

The short answer: chicks eat starter for the first 8 weeks, switch to grower from 8–18 weeks, then move to layer feed once they begin laying (typically around 18–20 weeks). Get the timing wrong and you either stunt a chick's development or overload a young pullet's kidneys with calcium she can't use yet. Here's what each feed is actually doing and how to time the transitions.

What Chick Starter Feed Is and Why It Matters

Chick starter is a high-protein formula designed for the explosive early growth phase. Most commercial starters run 18–22% protein, which fuels feather development, organ growth, and muscle tissue in those first weeks. Some medicated starters also include amprolium, a coccidiostat that helps chicks build resistance to coccidiosis (a genuine killer of young birds) without being an antibiotic.

A few things to know:

• Medicated vs. unmedicated: If your chicks were vaccinated for Marek's disease at the hatchery, double-check with your supplier whether medicated starter is appropriate (the interaction is generally fine, but it's worth confirming). If you hatched your own eggs or skipped the Marek's vaccine, medicated starter is typically a smart call for the first 4–6 weeks.
• Crumble or mash form: Most starter comes as fine crumbles or mash, which suits tiny beaks. Pellets are too large for most chicks under 8 weeks.
• Feeding amounts: Chicks are grazers by nature. Fill the feeder and let them eat freely. Ad-libitum feeding is standard for the first 8 weeks. A group of 10 chicks will typically go through roughly 2 lbs of starter per week in the first few weeks, ramping up as they grow.

Keep the feeder clean and dry. Wet, moldy starter can cause aspergillosis (a fungal lung infection), which is serious and difficult to treat. If you spot damp clumps, throw them out and clean the feeder before refilling.

Grower Feed for Pullets: Weeks 8–18

Once chicks hit about 8 weeks and look less like fluffy marbles and more like actual chickens, it's time to move to grower feed. Grower typically runs 16–18% protein, slightly lower than starter but still adequate for the continued growth phase.

The key difference between grower and layer feed is calcium content. Layer feed is loaded with calcium (typically 3.5–4.5%) to support eggshell production. That's exactly what a laying hen needs. But a pullet who isn't laying yet doesn't need that calcium, and forcing her system to process it before her kidneys are ready can cause kidney damage and gout-like conditions. This is the main reason you don't jump from starter straight to layer feed.

Grower feed keeps calcium low (around 0.9–1.1%) while maintaining enough protein for muscle and frame development. Some manufacturers make a "starter/grower" all-in-one product that runs through week 16 or 18. These are convenient for small flocks and work fine.

If you have a mixed flock with both young pullets and laying hens, this phase gets a bit tricky. See the mixed-flock section below.

Layer Feed: The Switch at 18–20 Weeks (or First Egg)

Layer feed is what most people picture when they think of "chicken feed." It typically runs 15–17% protein and that high calcium figure (3.5–4.5%) needed for strong shells.

The standard guideline is to switch to layer feed at 18 weeks, or when you see the first egg, whichever comes first. In practice, you'll often notice behavioral cues before the first egg arrives: pullets start squatting when you reach for them (the mating crouch), combs redden and enlarge, and you might catch them investigating nest boxes. Those are your signals that laying is imminent.

For a deeper look at everything you can offer laying hens, our complete guide to what to feed backyard chickens covers the full picture including kitchen scraps, treats, and seasonal adjustments.

One point keepers often overlook: the calcium in layer feed is not a substitute for offering oyster shell free-choice on the side. Even with layer feed, some hens (especially heavy producers like Leghorns or ISA Browns) may need the extra supplemental calcium available in a separate dish. Thin-shelled or soft eggs are a reliable signal that calcium availability is falling short. For more on this, our guide on grit and oyster shell explains the difference between the two and why each matters.

Comparing the Three Feeds at a Glance

Feed Type	Age Range	Protein %	Calcium %	Notes
Starter (medicated)	0–8 weeks	18–22%	~0.9%	Amprolium for cocci resistance
Starter (unmedicated)	0–8 weeks	18–22%	~0.9%	Use if chicks are vaccinated
Grower	8–18 weeks	16–18%	~1.0%	Keeps calcium low during growth
Starter/Grower (combo)	0–16–18 weeks	18–20%	~0.9%	Convenient for small flocks
Layer	18+ weeks / first egg	15–17%	3.5–4.5%	Add oyster shell free-choice

Managing a Mixed Flock (Different Ages Together)

If you're adding new chicks or pullets to a coop that already has laying hens, you have two main options:

Option 1: Feed everyone grower or an "all-flock" feed, then provide oyster shell in a separate dish free-choice. Laying hens will self-regulate their calcium intake from the dish, and the younger birds won't be force-fed calcium they can't handle. This is the simplest approach and works well for most backyard keepers.

Option 2: Separate feeding areas with a physical divider or a feeder the younger birds can access but the hens can't (small-gap feeders exist for this). This lets you keep everyone on age-appropriate feed, but it requires more management.

Most keepers with mixed flocks land on Option 1. All-flock or "flock raiser" type feeds (typically 18–20% protein, low calcium) are sold specifically for this situation and make it easy. Just keep that oyster shell dish reliably stocked.

Whatever approach you choose, keep treats and kitchen scraps to under 10% of the diet so they don't dilute the protein and mineral balance of the main feed. Scratch grains in particular are high in carbohydrates and low in protein. They're fine as an occasional treat, especially in cold weather, but they're not a substitute for a balanced feed. See our guide on safe treats and kitchen scraps for a solid run-down of what's worth offering.

Signs You've Got the Transition Timing Wrong

It helps to know what "off" looks like so you can course-correct:

• Soft or thin eggshells from laying hens: Most commonly points to insufficient calcium. Confirm your hens are actually getting layer feed (not grower) and that oyster shell is freely available.
• Slow feathering in chicks under 8 weeks: Could mean the starter protein is too low, or the chicks are too cold and burning energy on thermoregulation instead of growth. Check brooder temps (95°F the first week, dropping 5°F per week).
• Pale combs or poor production in adult hens: Multiple causes, but a nutritional shortfall is worth ruling out. Check feed freshness (old feed oxidizes and loses nutritional value), protein percentage, and whether hens are getting enough total feed.
• Kidney issues or gout in young birds: This is rarer but can result from prolonged exposure to high-calcium layer feed before laying begins. If you're seeing lethargy and swollen joints in pullets under 18 weeks, contact a poultry veterinarian. Don't self-diagnose gout. A vet can confirm and advise on supportive care.

Feed quality also matters. Bags stored in damp or hot conditions go stale fast. A 50-lb bag that sits in a shed through a hot summer month may be significantly degraded by the time it's used. Store feed in a sealed, rodent-proof metal bin in a cool, dry location, and try not to buy more than a 2–3 week supply at a time during summer.

Frequently Asked Questions

Can I feed layer feed to chicks in an emergency if I run out of starter?

A day or two won't cause permanent damage, but layer feed's high calcium is genuinely problematic for young kidneys over the medium term. If you're out of starter, plain cracked corn or oats in small amounts buy you time, so get proper starter feed within a day or two. Don't make it a habit.

Do roosters need a different feed than hens?

Roosters do fine on grower feed or an all-flock formula, but layer feed is not ideal for them long-term for the same reason it's not great for pullets: the high calcium load is unnecessary and can stress their kidneys. If your flock includes roosters, moving everyone to an all-flock feed plus free-choice oyster shell is the cleaner solution.

At what age can chicks eat layer feed?

Not until they're laying or within a week or two of laying, which for most breeds is around 18–20 weeks. Some slower-maturing breeds (like Cochins or Brahmas) may not start laying until 24–28 weeks, so watch for the behavioral cues mentioned above rather than going purely by calendar.

My pullets started laying at 16 weeks. Should I switch to layer feed now?

Early-maturing pullets do sometimes start laying at 16 weeks. Once eggs are appearing, the hen's body is already producing calcium-intensive eggshells, so switching to layer feed at that point is appropriate. The egg is your signal, not the number on the calendar.

Is organic or non-GMO feed worth the premium for backyard chickens?

That's genuinely a personal choice. There's no peer-reviewed evidence that organic feed produces measurably different eggs in a backyard setting, but if it matters to you for other reasons, the nutrient profiles of organic feeds are comparable to conventional ones. The bigger factor for egg quality is usually access to outdoor foraging, not the organic label on the feed bag.