Metabolic Effects of Feeding “Carbohydrate-free” Diets to Chicks

Abstract

Experiments were conducted to study the metabolic effects of feeding chicks “carbohydrate-free” and “carbohydrate- and glycerol-free” diets. Diets containing 15.4 kcal metabolizable energy/g protein were fed since at this level protein is present in sufficient quantities to promote rapid growth, but is not in excess. Results showed that chicks fed “carbohydrate-free” diets in which non-protein energy was supplied by either soybean oil or soybean fatty acids maintained normal levels of blood glucose and muscle glycogen but showed a marked depression in level of liver glycogen. Studies also showed that blood levels of ketone bodies increased and level of liver fat decreased when chicks were fed “carbohydrate- and glycerol-free” diets containing soybean fatty acids, but remained normal when soybean oil served as the sole source of non-protein energy. Further studies showed that the ketogenic effects of feeding a “carbohydrate-free” diet containing soybean fatty acids could be overcome by the addition of protein in amounts to decrease the calorie-to-protein ratio from 15.4 to either 13.2 or 11.0 kcal metabolizable energy/g protein.