Feed Conversion Efficiency Calculator

Feed conversion ratio is feed consumed divided by live weight gained over the same period, so an FCR of 2.0 means two kilograms of feed bought one kilogram of gain. It is the single most watched number in intensive animal production because feed usually represents 60 to 70 percent of the cost of producing a broiler or a finished pig, and the inverse form, feed efficiency as a percentage, conveys identical information with the more intuitive direction that higher is better. Species benchmarks differ enormously and reflect metabolism, not management quality: modern broilers finish at 1.55 to 1.85 over a 35 to 42 day grow-out, farmed Atlantic salmon reach 1.1 to 1.3 because a cold-blooded animal spends nothing on thermoregulation and little on skeletal support, grow-finish pigs run 2.5 to 3.0, and feedlot cattle 5.5 to 8.0. Average daily gain and daily feed intake per animal, both reported here, separate a genuinely efficient flock from one that is merely being grown slowly. Several interpretation traps are worth knowing. FCR is not dimensionless in any useful sense unless feed moisture and the weight basis are stated: as-fed versus dry-matter feed, and live weight versus carcass weight, can shift the number by 20 percent or more, which makes cross-farm comparison unreliable without agreed conventions. Mortality distorts the ratio because feed eaten by animals that died still counts against surviving gain. Ratios also drift upward through a production cycle, since maintenance energy scales with body mass while gain slows, so a late-finished animal always converts worse than a young one. The protein and caloric efficiency figures shown here use nominal compositions - roughly 20 percent crude protein in feed and 18 percent in gain - and should be treated as indicative rather than analytical values.

Quantifying what an animal returns for what it eats began with nineteenth-century agricultural chemistry. Albrecht Thaer proposed hay-equivalent values for comparing feeds in the early 1800s, and at the Weende experiment station in Germany, Wilhelm Henneberg and Friedrich Stohmann developed the proximate analysis scheme in the 1860s that split feed into moisture, ash, crude protein, crude fat, crude fibre and nitrogen-free extract - a classification still printed on feed tags. Oskar Kellner extended this into starch equivalents around 1905, and in the United States Henry Prentiss Armsby built a respiration calorimeter at the Pennsylvania State College early in the twentieth century to measure the energy an animal actually retained, laying the basis for net energy feeding systems. FCR became a competitive industrial metric with the vertical integration of poultry production. The Chicken of Tomorrow contests, organised in the United States in the late 1940s with support from the retailer A and P and the Department of Agriculture, rewarded breeders for meat yield and growth rate and set off decades of intense genetic selection; broiler FCR fell from roughly 4.0 in the 1950s to below 1.7 today, with grow-out time cut by more than half. The National Research Council in the United States began publishing its Nutrient Requirements of Domestic Animals series in the 1940s, giving formulators the reference values that made precise diets possible. More recently, genomic selection has allowed breeders to improve feed efficiency without measuring individual intake, and residual feed intake has emerged alongside FCR as a metric that separates efficiency from sheer growth rate.