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Peep & Pen

Stage 3 — from the move outside, onward

Layer, starter, all-flock and scratch: what actually separates them

Four bags in the same aisle, and the difference between them is mostly one number. Read the calcium and everything else follows.

By Scooter M.·Published September 1, 2026

A close-up of mixed grain and corn

The short answer

Calcium is the dividing line. Starter and grower feeds cap calcium around 1.25 percent because growing birds cannot use more. Layer feed carries much more for shell formation. All-flock splits the difference at low calcium and expects you to offer oyster shell separately. Scratch is not a complete feed at all.

The four bags

What each feed type is for.
FeedForProteinCalciumComplete feed?
StarterDay one to layingAround 18%Capped, around 1.25% maxYes
GrowerMid-growth in some rangesAround 16-18%CappedYes
LayerFrom the first egg onwardAround 16%High, for shell formationYes
All-flock / flock raiserMixed-age or mixed-species flocksAround 18-20%LowYes, plus free-choice oyster shell
ScratchA treatLowLowNo — it is a snack

Purina publishes 18.00 percent crude protein and calcium of 0.75 to 1.25 percent for Start & Grow, and its feeding direction is explicit: feed it continuously as the sole ration from day one until the onset of egg production, then switch to a layer feed. That single line answers the switching question better than any rule of thumb about weeks.

Why calcium is the dividing line

An eggshell is largely calcium carbonate, and a laying hen puts a remarkable amount of calcium into one every day or two. Layer feed exists to supply it.

A growing pullet is not doing that. Feed her the same calcium and she cannot use it, and the excess is handled by her kidneys — which is the reason chick starter caps calcium rather than simply not adding it. This is why “feed layer pellets from the start, it is simpler” is bad advice, and why the caps on the starter labels are maximums rather than minimums.

All-flock, and why it exists

All-flock or flock-raiser feeds are formulated at a decent protein level with low calcium, on the assumption that you will put oyster shell out free-choice so the laying birds take what they need and everybody else does not.

That makes it the right answer for a mixed flock: pullets and laying hens together, or chickens with ducks, or a flock with a rooster in it. Roosters have no use for layer calcium either.

For a flock of laying hens all the same age, layer feed plus free-choice oyster shell is simpler and usually cheaper. All-flock is a solution to a mixing problem.

Scratch is not chicken feed

Scratch is cracked corn and grains. It is a treat, it is low in protein, and it is not balanced. Birds love it, which is exactly the problem: a flock filling up on scratch is a flock not eating its complete feed, and the effects show up in shell quality and feather condition before they show up anywhere obvious.

The usual guidance is to keep treats of all kinds to a small proportion of the diet and to feed scratch in the afternoon, so the birds have eaten properly first. In winter a little scratch before roosting is genuinely useful because digesting it generates heat overnight.

Any bird eating scratch also needs grit, because whole grain has to be ground in the gizzard and a bird with no stones cannot do it. Grit and oyster shell covers that.

Reading a guaranteed analysis

Four lines tell you nearly everything:

  • Crude protein, minimum. 18 percent for growing birds, around 16 for layers, higher for all-flock.
  • Calcium, minimum and maximum. A maximum near 1.25 percent means a growing feed. A high minimum means a layer feed.
  • Lysine and methionine. The two limiting amino acids, which is why they are broken out separately. Higher is better within the same feed type.
  • Crude fiber, maximum. Lower means more of the bag is doing nutritional work.

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The short answer

The short list

Ranked on the published rubric. Every row jumps to that product's full write-up below; the button goes straight to Amazon.

#PickBest forKey specScorePrice
1
Score8.6

Our pick

Purina

Start & Grow Medicated Chick Feed

Eighteen percent crude protein with amprolium at 0.0125 percent, and a feeding direction that tells you exactly when to stop: day one until the first egg, then switch.

Chicks from a mixed-source order18% protein8.6of 10
2
Score8.3

Manna Pro

Crushed Oyster Shell

Thirty-three to thirty-eight percent calcium in a crushed form, offered free-choice — the supplement that fixes thin shells and the one most first-time keepers confuse with grit.

Shell quality once laying starts33-38% calcium8.3of 10
3
Score7.6

Manna Pro

Poultry Grit with Probiotics

Insoluble crushed granite, which is the actual definition of grit and the reason it is not oyster shell — a bird with no access to stones cannot digest whole grain, scratch or grass.

Birds eating anything but crumbleInsoluble crushed granite7.6of 10

#ad No live price feed on this build yet, so every button reads “check price” rather than showing a figure we cannot stand behind. Scores are our own published rubric, not customer ratings.

Score8.6no photo yet

#1 · Chicks from a mixed-source order

Purina Start & Grow Medicated Chick Feed

Eighteen percent crude protein with amprolium at 0.0125 percent, and a feeding direction that tells you exactly when to stop: day one until the first egg, then switch.

Who it is for. Anybody with unvaccinated chicks, and particularly anybody brooding on reused bedding or in a space that has held birds before.

Published specifications

Crude protein (min)
18.00%
Medication
Amprolium, max 0.0125% (113.50 g/ton), to help prevent coccidiosis
Lysine (min)
0.90%
Methionine (min)
0.30%
Crude fat (min)
3.00%
Crude fiber (max)
5.00%
Calcium
0.75% min, 1.25% max
Phosphorus (min)
0.40%
Vitamin A (min)
5,000 IU/lb
Feeding directions
Feed continuously as the sole ration from day one until onset of egg production, then switch to a layer feed

Source: Purina Animal Nutrition, Start & Grow Medicated product page and guaranteed analysis (purinamills.com), retrieved 2026-09-01

Rubric — 8.6 / 10

  • Capacity honesty9/10 · weight 26%
  • Documentation10/10 · weight 24%
  • Build and weather8/10 · weight 20%
  • Running cost7/10 · weight 15%
  • Daily use8/10 · weight 15%

What it gets right

  • Purina publishes the complete guaranteed analysis including the amprolium level, which not every brand does
  • Amprolium is a coccidiostat, not an antibiotic, and the label says so plainly
  • The feeding direction is unambiguous about when to stop, which is the question every first-time keeper asks
  • Calcium is capped at 1.25 percent — the low level growing birds need, and the reason chick feed is not layer feed

What it costs you

  • Medicated feed is the wrong choice if your chicks were vaccinated for coccidiosis at the hatchery; amprolium can interfere with the vaccine
  • 18 percent is standard rather than exceptional across this category
  • Sold mainly in 25 and 50 lb bags, which is a lot of feed for six chicks and it does not keep forever

Skip it if. Your chicks arrived coccidiosis-vaccinated. Ask the hatchery, and if they were, buy the unmedicated version of whatever you feed.

Check price on Amazon

#ad No live price feed yet, so no number is shown rather than a stale one. How this is funded.

Score8.3no photo yet

#2 · Shell quality once laying starts

Manna Pro Crushed Oyster Shell

Thirty-three to thirty-eight percent calcium in a crushed form, offered free-choice — the supplement that fixes thin shells and the one most first-time keepers confuse with grit.

Who it is for. Anybody whose hens have started laying, particularly if shells are thinning or breaking in the nest.

Published specifications

Calcium
33.00% min, 38.00% max
Ingredients
Oyster shell and coral calcium
Form
Crushed, coarse granules
Purpose
Calcium supplement for laying hens

Source: Manna Pro, Oyster Shell guaranteed analysis (product listing), retrieved 2026-09-01

Rubric — 8.3 / 10

  • Capacity honesty8/10 · weight 26%
  • Documentation8/10 · weight 24%
  • Build and weather8/10 · weight 20%
  • Running cost9/10 · weight 15%
  • Daily use9/10 · weight 15%

What it gets right

  • A published calcium range, which is the entire point of the product and is not always stated
  • Coarse crushed form dissolves slowly in the gizzard, which is what a hen forming a shell overnight needs
  • Offered free-choice in a separate dish, so birds that need it take it and pullets that do not, do not

What it costs you

  • Not grit, and it will not grind grain — the two products are routinely bought interchangeably and are not interchangeable
  • Must never be mixed into feed for non-laying birds; excess calcium is hard on growing birds' kidneys
  • A bag lasts a small flock a very long time, so most of what you buy sits in storage

Skip it if. Your birds are not laying yet. Free-choice oyster shell belongs in the coop from the first egg, not from day one.

Check price on Amazon

#ad No live price feed yet, so no number is shown rather than a stale one. How this is funded.

Score7.6no photo yet

#3 · Birds eating anything but crumble

Manna Pro Poultry Grit with Probiotics

Insoluble crushed granite, which is the actual definition of grit and the reason it is not oyster shell — a bird with no access to stones cannot digest whole grain, scratch or grass.

Who it is for. Any confined flock that gets scratch, treats or greens, which is very nearly every backyard flock.

Published specifications

Material
Insoluble crushed granite
Added
Probiotics
Purpose
Aids proper digestion of coarse grains for all classes of poultry
Guaranteed analysis
Not published for the grit itself

Source: Manna Pro, Poultry Grit product listings, retrieved 2026-09-01

Rubric — 7.6 / 10

  • Capacity honesty8/10 · weight 26%
  • Documentation5/10 · weight 24%
  • Build and weather8/10 · weight 20%
  • Running cost9/10 · weight 15%
  • Daily use9/10 · weight 15%

What it gets right

  • Insoluble is the operative word and it is stated plainly: this stays in the gizzard and grinds, where oyster shell dissolves
  • Suitable for all classes of poultry, so one bag covers pullets and hens
  • Necessary the moment a bird eats anything that is not a complete crumble or pellet — treats, scratch, grass, kitchen scraps

What it costs you

  • Manna Pro publishes no guaranteed analysis or particle size for the grit itself, so you cannot check it is sized for your birds' age
  • The added probiotics have no published inclusion rate, which makes them hard to value
  • Birds with free range over stony ground find their own grit and do not need this at all

Skip it if. Your birds free-range over gravel or coarse soil and eat nothing but complete feed. They are already sorted.

Check price on Amazon

#ad No live price feed yet, so no number is shown rather than a stale one. How this is funded.

FAQ

Questions people actually ask

What is the difference between layer feed and all flock?

Calcium. Layer feed carries a high level for shell formation and suits a flock of laying hens all the same age. All-flock is formulated with low calcium and higher protein for mixed-age or mixed-species flocks, on the assumption that you offer oyster shell free-choice so only the laying birds take the calcium.

What is the difference between chicken feed and scratch?

Complete feed is nutritionally balanced and is the whole diet. Scratch is cracked corn and grains — a low-protein treat that is not balanced. Birds prefer it, which is the problem: a flock filling up on scratch is not eating its complete feed, and shell quality and feather condition suffer before anything obvious does.

When do I switch from starter to layer feed?

At the onset of egg production. Purina's own feeding direction on Start & Grow is to feed it continuously as the sole ration from day one until egg production starts, then switch. Age is a proxy that varies by breed; the first egg is the actual signal.

Can I feed layer feed to a rooster?

It is not ideal. A rooster has no use for the calcium in layer feed and, like a growing pullet, has to excrete the excess. A mixed flock with a rooster is the situation all-flock feed with free-choice oyster shell exists for — the hens take the calcium they need and nobody else does.

Where the numbers came from

Sources

Every figure cited on this page came from one of these documents. If one of them has changed since we read it, the number here is out of date and we would like to know.

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