Chickens need different feed at each stage of life, and the timing of each switch matters more than most flock owners realize. Getting it wrong, especially switching to layer feed too early, can cause serious health problems. The key transitions happen at around 6 to 8 weeks, 16 to 20 weeks, and during seasonal events like molting.
Starter to Grower: 6 to 8 Weeks
Chicks start on starter feed from day one. This is a high-protein formula (typically 20 to 22% protein) designed for rapid early growth. Around 6 to 8 weeks of age, you switch to grower feed, which drops the protein slightly to around 16 to 18% and adjusts the nutrient balance for steady development rather than explosive early growth.
This transition is the least risky of the bunch. Chicks are resilient at this age, and the nutritional difference between starter and grower isn’t dramatic. Still, a gradual switch over several days helps avoid any digestive upset.
Grower to Layer: 16 to 20 Weeks
This is the transition that trips up the most people. Layer feed contains significantly more calcium than grower feed, roughly 3 to 4% compared to under 1%. That calcium supports strong eggshells, and hens need it once they begin laying. But feeding it too early is genuinely dangerous.
Research published in Biomedical Reports confirms that high-calcium diets impair kidney function in young birds. In studies on immature chickens fed elevated calcium levels, birds developed kidney damage, visceral gout, weight loss, dehydration, and in some cases death. The kidneys became pale, enlarged or atrophied, and ureters filled with white urate crystals. This isn’t a minor concern. Excess calcium that a young bird’s body can’t use gets processed through the kidneys, and immature kidneys simply can’t handle the load.
The safe window to switch is 16 to 20 weeks, but age alone isn’t the best guide. Watch your birds for physical signs of sexual maturity instead.
Signs Your Pullets Are Ready for Layer Feed
A pullet approaching her first egg shows several visible changes. Her comb and wattles will enlarge noticeably and turn bright red, looking waxy and plump compared to the smaller, pale comb of an immature bird. She may begin squatting low to the ground with her wings spread out when you approach, a submissive posture that signals hormonal readiness. You might also catch her hopping into nesting boxes to investigate them a week or two before her first egg.
When you see these signs, it’s time to begin the transition to layer feed. If only some of your flock is showing signs of maturity, don’t rush the switch for the entire group. You have options for mixed-age flocks, which we’ll cover below.
How to Transition Between Feeds
Switching feed cold turkey can cause digestive problems and temporary drops in eating. Purina Canada recommends a three-week graduated approach:
- Week 1: 75% old feed, 25% new feed
- Week 2: 50% old feed, 50% new feed
- Week 3: 25% old feed, 75% new feed
After three weeks, you can offer the new feed exclusively. This schedule works for any feed transition, whether you’re moving from starter to grower, grower to layer, or switching to a higher-protein formula during molt.
Feeding During Molt
Most hens molt once a year, typically in fall as daylight hours decrease. They lose feathers and regrow them over 8 to 12 weeks. Feathers are roughly 85% protein, so this period puts a heavy nutritional demand on your birds that standard layer feed (16 to 18% protein) can’t fully meet.
Many flock owners temporarily switch to a higher-protein feed during molt, bumping up to 20 to 22% protein. You can use a game bird feed, a flock raiser formula, or supplement regular feed with high-protein treats like sprouted lentils, fully cooked beans, or scrambled eggs. Once feathers have grown back in and laying resumes, transition back to regular layer feed. If you feed fish as a protein source, be aware it can affect the taste of the eggs.
Meat Birds Follow a Different Schedule
If you’re raising broilers rather than layers, the timeline compresses dramatically. Meat breeds grow fast and reach processing weight in roughly 6 to 8 weeks, so the feeding phases are measured in days rather than months.
A typical broiler schedule runs through up to five phases: a prestarter for the first 6 days (about 100 grams per bird), a starter diet from days 6 to 14, a grower diet from days 14 to 28, a finisher from day 28 until about 5 days before processing, and a final withdrawal-phase feed for those last few days. If you’re raising a dual-purpose breed rather than a commercial broiler, the schedule stretches out and looks more like the layer timeline above.
Mixed Flocks and All-Flock Feed
If your flock includes birds at different life stages, roosters, or non-laying breeds alongside active layers, an all-flock feed solves the calcium timing problem. All-flock formulas typically contain around 20% protein with moderate calcium, making them safe for birds of any age.
The trade-off is that all-flock feed doesn’t contain enough calcium for active laying hens. You compensate by offering crushed oyster shell in a separate dish. Hens that need calcium will eat it; birds that don’t will ignore it. This self-service approach lets each bird regulate her own calcium intake without forcing high-calcium feed on young pullets, roosters, or non-laying birds whose kidneys don’t need the extra load.
All-flock feed also works well as a base during molt, since its higher protein content (20% compared to 16 to 18% in layer feed) better supports feather regrowth. Just keep the oyster shell available for any hens still laying through the molt.
Quick Reference by Age
- Day 1 to 6–8 weeks: Starter feed (20–22% protein)
- 6–8 weeks to 16–20 weeks: Grower feed (16–18% protein)
- 16–20 weeks onward: Layer feed (16–18% protein, high calcium) once you see signs of maturity
- During molt: Temporarily increase to 20–22% protein
- Mixed flocks: All-flock feed plus free-choice oyster shell year-round