Feed conversion ratio (FCR)
In ROI and FCR Economics: total flock feed used ÷ live weight sold. Do not interchange this with gain-based or mortality-corrected FCR.
FCR on weight gain
Total feed used ÷ weight gain of birds completing the period. Gain = birds × (final − starting weight).
European Production Efficiency Factor (EPEF)
(Livability % × average live weight kg) ÷ (age in days × FCR) × 100.
Livability
Birds remaining alive as a percentage of birds placed. For a closed accounting period: livability = 100 − cumulative mortality percentage.
Mortality
Deaths ÷ birds placed × 100 for the same period. Record culls separately when they are excluded from your mortality definition.
Weight / weight (w/w)
Grams of active ingredient per 100 g product. A 20% powder contains 200 mg active per g product.
Weight / volume (w/v)
Grams of active ingredient per 100 mL product. A 20% liquid contains 200 mg active per mL product.
Break-even
The value where compared margins match, or the feed-cost impact is zero. This is not a diagnostic or biological threshold.
Return on additive cost (ROI)
Incremental profit ÷ additive cost × 100. Incremental profit is the change between compared scenarios.
Units and conversion
1 lb = 0.45359237 kg; metric tonne = 1,000 kg; US short ton = 907.18474 kg; US gallon = 3.785411784 L. No exchange-rate conversion is applied.