How to Calculate Feed Cost per Kilogram of Gain

Most farms talk about feed cost. Far fewer can produce the only feed-cost number that actually drives profit on demand: cost per kilogram of gain, this batch, this barn, today.

The good news is that the calculation takes about five minutes if the underlying weekly records are clean.

The bad news is that most farms either do not keep those records, or keep them in inconsistent units that distort the answer.

Without this number you cannot compare rations, suppliers, growth phases or barns on a fair basis. You are flying on bag price — the cheapest data and the most misleading.

Cost per kg of gain is also the single most useful metric for nutritionist conversations, supplier negotiations, and investor reporting. It speaks both biology and finance.

And because it depends on FCR, it forces the farm to clean up its weighing and feed-recording discipline — which alone improves performance.

Core formula: Cost per kg gain = (Total feed consumed in kg × Feed price per kg) ÷ Total live weight gained in kg.

Equivalent shortcut: Cost per kg gain = FCR × Feed price per kg. Useful for quick sensitivity testing.

Run the calculation per batch, per barn, per ration, and per growth phase (starter, grower, finisher) — never just whole-cycle.

Common distortions to avoid: mixing as-fed and dry-matter intake; counting feed deliveries that have not yet been consumed; using start and end weights from different scales; ignoring mortality (weight gain must be calculated on pigs sold, not pigs started).

For breeding herds, allocate sow feed across weaned piglets to get a true cost per kg of weaned weight.

A finishing batch of 100 pigs is closed out at market.

Total feed consumed in the finishing phase: 18,000 kg. Feed price: $0.40/kg ($400/t).

Start weight: 30 kg/pig × 100 pigs = 3,000 kg total. End weight: 105 kg/pig × 98 pigs sold (2 mortalities) = 10,290 kg. Weight gained = 10,290 − (98 × 30) = 7,350 kg.

Cost per kg of gain = (18,000 × 0.40) ÷ 7,350 = $0.98/kg.

Implied FCR = 18,000 ÷ 7,350 = 2.45. Sense-check against the herd benchmark; if it looks too good, audit before celebrating.

Now the number is comparable: to last batch, to a competing ration, to the industry benchmark, and to next quarter's forecast.

• Weigh every feed delivery and every pig batch on the same calibrated scales using a documented protocol.
• Record mortality and cull weights so that 'weight gained' is calculated on pigs actually sold.
• Run the calculation per growth phase, not just whole-cycle — most of the variation lives in the finisher.
• Store the result in your KPI dashboard alongside FCR and ADG, with a 4-period trend.
• Re-run after every ration change to confirm the change paid for itself in cost per kg of gain, not just in bag price.
• Treat any cost-per-kg-gain reading that beats the herd benchmark by >10% as suspect until audited.

If you can weigh, multiply and divide, you can run the most important number in livestock economics. Do it every week, in the same units, by the same person — and protect it from the small inconsistencies that quietly destroy its meaning.