National Geographic : 2014 Jun
GRAPHIC AND CHART BY VIRGINIA W. MASON AND JASON TREAT, NGM STAFF; SHELLEY SPERRY SOURCES: MALCOLM BEVERIDGE, WORLDFISH; RODNEY HILL, UNIVERSITY OF IDAHO; ROBERT SWICK, UNIVERSITY OF NEW ENGLAND, AUSTRALIA; U.K . AGRICULTURE AND HORTICULTURE DEVELOPMENT BOARD Cattle* 1 pound of feed Pigs Fish** Broiler chickens 1.7 6.8 1.1 2.9 1 POUND BODY MASS Exactly how much feed is needed varies, depending on the quality and makeup of the feed, the health and age of the animal, the environ- ment, and other factors. Pounds of feed needed to produce one pound of body mass *Hereford ratio; ratios for other cattle breeds vary **Salmon ratio; ratios for other fish slightly higher Pounds for Pound Different sources of animal protein in our diet place different demands on natural resources. One measure of this is the “feed conversion ratio”: an estimate of the feed required to gain one pound of body mass. By this measure, farming salmon is about seven times more efficient than raising beef.