EPEF — broiler performance efficiency factor (formula and example)
EPEF (European Production Efficiency Factor) is a single number that tells you how well a flock performed. The higher it is, the better. We explain where it comes from, how to calculate it step by step, and how to read the result.
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A poultry farmer needs to answer one question: did this batch go well, or could it have been better? Slaughter weight alone does not tell you — a bird can be heavy but eat too much feed or take too long to grow. EPEF combines four things: how many birds survived to slaughter, how much they weighed, how many days they grew, and how much feed they ate per kilogram of gain. This is part of the broiler cluster — you can find the full production picture in the guide on broiler farming.
What does EPEF stand for?
EPEF stands for European Production Efficiency Factor. In Polish it is also abbreviated as EWW (Europejski Wskaźnik Wydajności). Both abbreviations mean exactly the same thing and are used interchangeably in the industry.
Where do the numbers in this guide come from?
The worked examples and indicative thresholds refer to the production targets published by Aviagen for the Ross 308 line (Ross 308 Performance Objectives 2022). Your results may differ depending on the genetic line, farm conditions, season and flock management — treat them as reference points. FCR is calculated separately — the step-by-step method is in the guide on broiler FCR — how to calculate.
How to calculate EPEF — a worked example with real numbers
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Step 1 — establish flock survival [%]
Survival is the percentage of birds that made it to slaughter. Calculate it as: (birds slaughtered ÷ birds placed) × 100. In our example: 20,000 birds placed, 800 died or were culled, so 19,200 went to slaughter. Survival = 19,200 ÷ 20,000 × 100 = 96%. The higher the percentage, the better — every dead bird represents wasted feed, heating costs, and time.
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Step 2 — check average live weight [kg]
Average live weight is the mean weight of a bird at slaughter in kilograms — live weight, not after plucking. The slaughterhouse provides this in the settlement documents (weight ticket). In our example it is 2.6 kg. How weight develops week by week is covered in the guide on broiler weight and growth — table.
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Step 3 — record the flock age at slaughter [days]
Age is the number of days from chick placement to the day of slaughter. In our example the flock was slaughtered on day 42. It is worth checking this precisely — a difference of one day moves EPEF by several points, because a longer growth period means more feed consumed and a higher denominator in the formula.
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Step 4 — read the flock FCR
FCR (Feed Conversion Ratio) tells you how many kilograms of feed were consumed for every kilogram of live-weight gain. If the flock ate 80,000 kg of feed and gained 50,000 kg (final weight minus initial weight), then FCR = 80,000 ÷ 50,000 = 1.60. The lower the FCR, the better — the bird is converting feed into meat more efficiently. The step-by-step FCR calculation is in the guide on broiler FCR — how to calculate. In our example FCR is 1.55.
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Step 5 — calculate the numerator (top of the fraction)
The numerator is: survival × live weight. In our example: 96 × 2.6 = 249.6. Note: survival is entered as a plain number (96, not 0.96). This is important — otherwise the result will be 100 times smaller.
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Step 6 — calculate the denominator (bottom of the fraction)
The denominator is: age × FCR. In our example: 42 × 1.55 = 65.1. A large denominator means a long growing period and/or poor feed efficiency — both factors pull EPEF down.
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Step 7 — divide and multiply by 100
Final EPEF = (numerator ÷ denominator) × 100. In our example: (249.6 ÷ 65.1) × 100 = 3.834… × 100 ≈ 383. This is a decent result. Below you will find an interpretation table showing what this number means in practice.
What does your EPEF result mean? — indicative table
The thresholds are indicative and depend on the genetic line, season and market conditions. Treat them as reference points, not fixed norms. Source: industry benchmark, with reference to Aviagen Ross 308 2022 targets.
Above about 400 — very good
The flock achieved above-average results for commercial broiler production. Low mortality, good live weight, short growing period and/or low FCR all contributed to the high index. It is worth identifying what worked well and replicating those conditions in the next cycle.
About 350–400 — decent
A result within the normal range for many production farms. There is room for improvement, but none of the four variables stands out as an obvious problem. Look at whether you can shorten the growing period by one or two days without losing weight, or lower FCR through better-balanced feed.
Below about 350 — room for improvement
At least one variable is dragging the result down. Check in sequence: survival (mortality), FCR (feed consumption), live weight relative to age. If FCR is high with good weight, the problem may be in the feed formula or watering conditions. A low EPEF with high mortality is a signal to consult a veterinarian.
How to improve EPEF?
EPEF improves when: (1) mortality falls — good biosecurity, vaccination, chick quality; (2) live weight rises — good starter feed, uniform flock; (3) growing period shortens — reaching target weight sooner; (4) FCR falls — less feed per kilogram of meat. Changing one variable by a few percent can move EPEF by ten to thirty points. The digital flock record in the DlaFerm.pl app calculates EPEF automatically after each cycle — see the digital broiler flock record.
Frequently asked questions about EPEF
What is the EPEF formula for broilers?add
EPEF = (survival [%] × average live weight [kg]) ÷ (age at slaughter [days] × FCR) × 100. Important: survival is entered as a plain number (e.g. 96, not 0.96), weight in kilograms, FCR as a decimal (e.g. 1.55). Example: 96 × 2.6 = 249.6; 42 × 1.55 = 65.1; 249.6 ÷ 65.1 × 100 ≈ 383.
What is a good EPEF for broilers?add
As a rough guide: above about 400 is a very good result; about 350–400 is a decent result for a normal farm; below about 350 is a signal that at least one of the variables (mortality, FCR, weight, age) needs improvement. Thresholds vary between genetic lines and seasons — always compare with previous cycles on the same farm.
Does a higher EPEF always mean higher profit?add
Almost always, because a higher EPEF usually means fewer losses, better weight and lower FCR — all of which translate to lower costs and higher flock value. Exception: if the slaughterhouse pays by weight with a bonus for a specific weight bracket, very high weight does not always mean a better price per kilogram. But EPEF as a production index remains a reliable measure of fattening efficiency.
Can I compare the EPEF of different flocks?add
Yes, but with caution. EPEF is a good measure for flocks of the same genetic line and similar slaughter age. Comparing a 38-day flock with a 48-day flock can be misleading because a longer growing period mechanically lowers EPEF, even if the flock is healthy and eating efficiently. It is best to compare successive cycles on the same farm at similar slaughter ages.
How does survival rate enter the formula?add
Survival (the percentage of birds that made it to slaughter) enters as a number between 0 and 100 — for example 96 if 4% of the flock died. The higher the survival, the higher the numerator, and the higher the EPEF. A flock with 99% survival and otherwise identical parameters to one with 94% survival will have an EPEF roughly 5% higher. Reducing mortality is therefore one of the most effective ways to improve the index.
What is FCR and how does it affect EPEF?add
FCR (Feed Conversion Ratio) measures how many kilograms of feed are needed to produce one kilogram of live-weight gain. It sits in the denominator of the EPEF formula, so a lower FCR always raises EPEF, all else being equal. A flock with FCR 1.45 will have a noticeably higher EPEF than one with FCR 1.75, even with the same survival, weight and age. The step-by-step FCR calculation is in the guide on broiler FCR — how to calculate.
DlaFerm.pl calculates EPEF for you
Do not want to calculate by hand? The digital flock record in DlaFerm.pl works out EPEF automatically after every cycle — just enter the flock data. Create a free farm account or write to us.
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