What the feed conversion ratio is
The feed conversion ratio (FCR) measures how efficiently animals turn feed into body weight:
FCR = feed eaten ÷ weight gained
Both quantities are in the same unit, so an FCR of 1.7 means 1.7 lb of feed for each pound of gain. Lower is better. Feed is usually the largest cost in animal production, often 60% to 70% of the cost of raising broilers, so small changes in FCR have a big effect on profit.
Example
A backyard batch of 50 broilers grows from 0.09 lb to 6.2 lb each and eats 525 lb of feed:
- weight gained = 50 × (6.2 − 0.09) ≈ 305.5 lb;
- FCR = 525 ÷ 305.5 ≈ 1.72.
At $0.25 per lb of feed, each pound of gain costs about $0.43 in feed, and the batch ate about $131 worth.
Typical values
| Animal | Usual FCR |
|---|---|
| Fast-growing broiler chickens | 1.5 to 1.9 |
| Slow-growing or heritage chickens | 2.5 to 3.5 |
| Turkeys | 2.5 to 3 |
| Growing-finishing pigs | 2.5 to 3 |
| Beef cattle in a feedlot | 5 to 8 |
| Farmed fish such as tilapia or salmon | 1 to 1.5 |
Fish convert feed well because they are cold-blooded and buoyant, so they spend little energy on heat and support.
Feed efficiency
The inverse of FCR, gain ÷ feed, is called feed efficiency. An FCR of 1.72 is a feed efficiency of 58%.
What affects FCR
- Genetics: modern broiler strains are bred for fast growth and low FCR.
- Age: FCR rises as animals get older and heavier, which is one reason to choose the slaughter weight carefully.
- Feed quality and waste: spilled feed counts as eaten. Feeders adjusted to the height of the birds’ backs reduce waste.
- Temperature: in cold weather animals burn feed to stay warm; in heat they eat less.
- Health: parasites and disease waste feed.
- Mortality: dead animals ate feed but add no final weight. Professional calculations often include their weight to avoid penalizing the FCR.
Tips
Weigh a sample of animals at the start and end rather than guessing, and record every bag of feed. Comparing FCR between batches is one of the simplest ways to see whether a change in feed, housing or breed pays off.