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History of fish nutrition Part I: 1900-1958 Ronald W. Hardy, Distinguished Professor Emeritus, Aquaculture Research Institute, University of Idaho This is the first of a series of articles titled "History of fish nutrition".
Fish nutrition is a relatively new field of study in the realm of animal and human nutrition. Fish nutrition research evolved by exploiting discoveries in animal and human nutrition over the past 100 years. These discoveries, in turn, built upon the foundation of information obtained over the previous century to characterize the nutrient and energy contents foods and animal matter, measure the metabolism of dietary energy and protein and identify the relationship between certain foods and human and animal diseases.
Discoveries from animal nutrition At first, the main function of food was assumed to provide fuel for the body, similar to fuel for a furnace. Obviously, animals do not literally ‘burn’ food, but they were shown to extract energy from food for heat and activity by a similar but unknown mechanism. Dietary protein was assumed to be incorporated more-or-less directly from foods into tissue protein without much change (Carpenter, 2003a). Animals were found to be useful subjects to study human nutrition. Dogs were especially popular because they would consume diets comprised of a single ingredient. One scholar wrote in 1816 that “Everyone knows that dogs can live very well on bread alone” (Magendie, cited by Carpenter, 2003a). However, when this statement was put to the test, dogs fed bread alone did not survive more than 50 days, suggesting that it lacked some essential materials to support life. Fresh animal meat and bones supported sustained growth and health of dogs, but refined animal products, such as gelatin extracted from bones or meat extracted with water, did not. Magendie suggested that water
extraction of meat removed materials that were essential in the diet, possibly iron or other salts, fatty material or lactic acid. Despite this scientific insight, more than 75 years passed before scientists returned to studying the constituents of meats and other foods that were necessary for feeds containing purified ingredients to support animal growth. One of the reasons for this was the publication of an influential book by Liebig in 1842 entitled Animal Chemistry or Organic Chemistry in its Application to Physiology and Pathology. Leibig argued that muscle tissue only contained protein and therefore muscle contraction came from an energy-yielding breakdown of protein molecules that powered muscles and produced urea. Therefore, he reasoned, protein was the only true nutrient (Carpenter, 2003a).
Nutrition through diseases Nutrition also advanced through studies of several disease conditions prevalent in populations deprived of specific foods. Since ancient times, it was known that night blindness and scurvy were cured by feeding certain foods, i.e. carrots for night blindness and limes/lemons for scurvy, a condition that plagued sailors at sea. In the late 19th century, rickets, a deformity of leg bones in children, became a widespread and serious problem in industrialized countries in Northern Europe as people moved from farms to polluted cities. The cause was unknown. Rickets was not associated with calcium intake but was cured by supplementing childrens’ diets with cod liver oil (Carpenter, 2003b). The finding that cod liver oil cured rickets supported
Aquafeed: Advances in Processing & Formulation Vol 14 Issue 2 2022