The efficiency of conversion of ingested food to unit of body substance (ECI, also termed "growth efficiency") is an index measure of food fuel efficiency in animals. The ECI is a rough scale of how much of the food
ingested
Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms inges ...
is converted into growth in the animal's
mass
Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...
. It can be used to compare the growth efficiency as measured by the weight gain of different animals from consuming a given quantity of food relative to its size.
The ECI effectively represents efficiencies of both
digestion
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...
(approximate digestibility or AD) and
metabolic efficiency, or how well digested food is converted to mass (efficiency of conversion of digested food or ECD). The formula for the efficiency of food fuel is thus:
:
These concepts are also very closely related to the
feed conversion ratio (FCR) and feed efficiency.
References
Food science
Metabolism
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