Calculating FCR correctly

What FCR measures

Feed conversion ratio (FCR) is the feed used divided by the weight gained. An FCR of 1.4 means 1.4 kg of feed for each kilogram of growth. Feed is usually the largest cost on a farm, so a small improvement in FCR makes a big difference to profit.

The formula

FCR = total feed given ÷ (final biomass − biomass stocked). Use the harvested weight plus any stock still in the pond as the final biomass, and include partial harvests.

• Count all feed, including feed that was wasted
• Subtract the stocked biomass: the seed weight was not produced by the feed
• Use the same units (kg) throughout

A worked example

A pond is stocked with 100,000 shrimp at 0.01 g (1 kg). Over the crop it receives 6,300 kg of feed. 4,000 kg is harvested in a partial harvest and 500 kg remains. Weight gained = 4,000 + 500 − 1 = 4,499 kg. FCR = 6,300 ÷ 4,499 = 1.40.

What good looks like

Good values depend on species, feed and system. Compare your ponds with each other and with your own previous crops rather than with a single published number, and watch the trend during the crop.

Common mistakes

• Estimating biomass from an old or too-small sample
• Forgetting partial harvests or mortality removals
• Comparing crops of very different lengths or final sizes
• Leaving feed records until the end of the week

How the portal helps

Feed given is recorded daily against each batch and taken out of stock automatically. Growth samples estimate biomass, and the Cycles and Profitability reports calculate FCR, cost per kilogram and margin per crop.