How much feed does a broiler eat — requirements by age
We explain in plain language how much feed one broiler needs from placement to slaughter and how to calculate how many tonnes of feed to order for a whole flock. Indicative values per Ross 308 — check them against your own line card, as actual consumption depends on the flock and conditions.
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Feed planning is one of the most important things before every flock. Too little feed in the silo means a feeding break. Too much ordered at once means feed goes stale or there is no room in the silo. To plan deliveries and silo filling you need to know how much feed you will use — and when. This guide gives you the numbers and the formula. A broader look at feeding phases is in the article broiler feeding phases — table.
What is cumulative feed?
Cumulative feed (also: feed on a running total basis) is how much feed one bird has eaten in total from day one of placement up to a given day. For example: if a bird has eaten a total of about 165 g of feed by day 7, the cumulative feed at day 7 is 165 g. By day 14 it has eaten a total of about 530 g — that is the cumulative feed at day 14. You do not add this on top of the previous week — the cumulative figure already includes all previous weeks.
Where do the values in this article come from?
The indicative values given in this article and the table below come from the document "Ross 308 Broiler Performance Objectives" published by Aviagen (aviagen.com, 2022). The figures refer to a mixed-sex flock. Actual consumption on your farm may differ — it depends on the line, flock health, house temperature, feed quality, feeder wastage and mortality. Treat these values as a planning starting point, not a firm guarantee. Feed standards and ingredients are covered in the separate article broiler nutrition — standards.
How to calculate the feed quantity for a whole flock
The formula is simple. Below is a step-by-step explanation of how to use it — and what to watch out for.
Basic formula
Feed quantity for the flock (kg) = number of birds × cumulative feed per bird up to the planned slaughter day (kg). This is a simplification — it assumes all birds survive to slaughter day. In practice some birds die (mortality), so actual consumption will be slightly lower. This simplification is used at the planning stage to build in a safety margin.
What does "planned slaughter day" mean?
Ross 308 broilers are typically slaughtered around day 35–42, depending on the target bird weight and processor requirements. Choose the slaughter day that applies to your flock and read the cumulative feed per bird for that day from the table. The most common scenario in Poland is slaughter around day 42 — cumulative feed is then about 4.59 kg per bird (per Ross 308).
Where to get an accurate feed conversion ratio?
The figures here are indicative values. If you know the FCR (Feed Conversion Ratio) from previous flocks and the planned slaughter weight, you can calculate more precisely: feed per bird (kg) = FCR × slaughter weight (kg). Typical FCR on Polish farms for Ross 308 at around day 42 is roughly 1.7–1.8 (indicative). The cost of that feed is covered in the article feed cost per kg of live weight — broilers.
How to break it down by feed phase?
In practice the feed for a flock is the sum of several feed phases (starter, grower, finisher). Each phase has a different composition and a different price. To plan each phase separately, check how many tonnes of feed you need between specific days — subtract the cumulative feed at the start of the phase from the cumulative feed at the end, then multiply by the number of birds. Feeding phases and their age ranges are covered in the article broiler feeding phases — table.
Example: 20,000 birds, slaughter at day 42
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Step 1 — establish the number of birds and slaughter day
In this example we assume: 20,000 day-old chicks placed, planned slaughter at day 42. This is a typical scenario for a Ross 308 broiler slaughtered at about 2.5–2.7 kg live weight.
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Step 2 — read the cumulative feed per bird to day 42
According to the Ross 308 Performance Objectives 2022, cumulative feed per bird to day 42 is about 4,590 g, i.e. about 4.59 kg. That is how much feed one bird eats in total from placement to day 42 (indicative, mixed-sex flock).
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Step 3 — calculate total feed for the whole flock
Multiply: 20,000 birds × 4.59 kg/bird = 91,800 kg of feed. That is about 91.8 tonnes of feed for the whole flock to day 42. That is how much you need to plan in deliveries and silo capacity.
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Step 4 — check your silo capacity
If each silo holds for example 15 tonnes of feed, you need at least 6 full silo fills for the flock (6 × 15 t = 90 t, plus about 1.8 t buffer — e.g. one extra delivery at the end). In the DlaFerm.pl app you can monitor the current feed level in silos and plan deliveries in advance — details in the module feed silo monitoring.
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Step 5 — plan deliveries in stages
You do not order all the feed at once — feed has a shelf life and takes up space. Look at the weekly table below: a bird consumes about 165 g by day 7, about 530 g by day 14, and so on. In weeks 3 and 4 the flock feed uptake is highest — that is when the silos empty fastest and deliveries must be most frequent.
Ross 308 cumulative feed — per bird, week by week
Each card shows how much feed one bird has eaten from placement to the end of the given week. Indicative values per Ross 308 (mixed-sex flock)*.
To end of week 1 (day 7)
Cumulative feed: approx. 165 g/bird (≈ 0.17 kg). For 20,000 birds: approx. 3,300 kg ≈ 3.3 tonnes. Chicks eat little — the main cost is heating energy, not feed. Starter is just getting going.
To end of week 2 (day 14)
Cumulative feed: approx. 530 g/bird (≈ 0.53 kg). For 20,000 birds: approx. 10,600 kg ≈ 10.6 tonnes. Feed uptake is rising fast. The starter phase usually ends around day 10–14.
To end of week 3 (day 21)
Cumulative feed: approx. 1,180 g/bird (≈ 1.18 kg). For 20,000 birds: approx. 23,600 kg ≈ 23.6 tonnes. The bird eats about 650 g in this week alone — more than three times week 1. Full grower phase.
To end of week 4 (day 28)
Cumulative feed: approx. 2,090 g/bird (≈ 2.09 kg). For 20,000 birds: approx. 41,800 kg ≈ 41.8 tonnes. The bird eats about 910 g this week — the mid-flock weekly record. Silos empty fastest now.
To end of week 5 (day 35)
Cumulative feed: approx. 3,250 g/bird (≈ 3.25 kg). For 20,000 birds: approx. 65,000 kg ≈ 65.0 tonnes. The bird eats about 1,160 g this week. Finisher phase running. Silos drain fastest here — check levels daily.
To end of week 6 (day 42)
Cumulative feed: approx. 4,590 g/bird (≈ 4.59 kg). For 20,000 birds: approx. 91,800 kg ≈ 91.8 tonnes — total for the whole flock. The bird eats about 1,340 g in the final week. Before slaughter a withdrawal period is applied per the processor's instructions (typically a few hours).
The most common feed planning mistakes
These mistakes can ruin even a good feed plan. Worth knowing before the first delivery.
Ordering all feed at once
Feed has a shelf life and loses nutritional value over time (especially vitamins). Ordering everything at once also risks running out of silo space. Plan deliveries in stages — ideally so that older feed is used before new feed arrives.
No safety margin
A delayed delivery, a broken-down truck, or faster-than-expected flock growth can all leave you without feed at the wrong moment. Always keep a buffer of 1–2 days of consumption, especially in weeks 4–6 when the flock eats the most.
Using the previous flock's figures without adjustment
Every flock is different — different weather, different chicks, different conditions. Figures from the previous flock are a good reference point but should be compared with the current breed guide and your own FCR history. Do not copy the plan without thinking.
Ignoring feed wastage
Overfilled feeders, wrong suspension height, damaged feed augers — all of these increase actual feed consumption above the table values. Ross 308 norms are the bird's minimum biological needs and do not account for feeder wastage. Your actual order should be about 3–8% higher, depending on feeder condition.
Frequently asked questions about broiler feed
How much feed does one broiler need by day 42?add
According to the Ross 308 Performance Objectives 2022 (Aviagen), one bird (mixed-sex flock) eats a total of about 4,590 g of feed from placement to day 42. That is about 4.59 kg per bird. This is an indicative value — actual consumption depends on flock health, temperature, feed quality and feeder wastage.
How do I calculate the feed I need for a whole flock?add
Simple formula: feed quantity (kg) = number of birds × cumulative feed per bird to slaughter day (kg). Example: 20,000 birds × 4.59 kg = 91,800 kg ≈ 91.8 tonnes to day 42. Add a margin of about 3–8% for feeder wastage.
What is FCR and how do I use it to plan feed?add
FCR (Feed Conversion Ratio) is how many kg of feed the bird used per kg of weight gain. Formula: feed per bird (kg) = FCR × planned slaughter weight (kg). Example: FCR 1.75 × 2.6 kg = about 4.55 kg of feed per bird. Your own farm FCR gives a more accurate result than table values.
When does the bird consume the most feed?add
Daily feed consumption increases throughout the flock and is highest in weeks 5–6 of life. According to indicative Ross 308 data, the bird eats about 1,160–1,340 g of feed in weeks 5–6 alone. That is when silos empty fastest and deliveries must be most frequent.
How do I plan silo capacity for a flock?add
Add up the feed for the whole flock over the whole flock (e.g. 91.8 tonnes for 20,000 birds to day 42), then divide by the capacity of one silo — that gives you the number of fills needed for the flock. Remember you do not keep all the feed at once — plan deliveries every few days. Details on silo monitoring are in the article feed silo monitoring.
Do these values apply to broiler lines other than Ross 308?add
Not necessarily. Other lines (e.g. Cobb 500, Hubbard) have different feed standards and different FCR. The figures in this article apply only to Ross 308 per the producer's document. For other lines, check the nutrition card from your chick supplier or the line breeder.
Sources & resources
Monitor feed and plan deliveries in DlaFerm.pl
Want to know how much feed is left in your silos and when to order the next delivery? The silo monitoring and feed planning module is available in the app. Create a free farm account or write to us.
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