“Extra Caloric” Effect of Dietary Fat for Developing Turkeys as Influenced by Calorie-Protein Ratio

INTRODUCTION STUDIES with both rats (Forbes et al., 1946; French et al., 1948; and Swift and Black, 1949) and chicks (Rand et al., 1958) have shown that adding fat to rations improved the utilization of metabolizable energy calories and protein. In a series of experiments with developing turkeys, Touchburn and Naber (1966) clearly demonstrated that dietary fat improved utilization of metabolizable energy and obtained evidence that a wider calorie : protein ratio could be tolerated when fat was added to the ration than when no fat was used. These authors referred to the “extra caloric” effect of supplemental dietary fat. In the absence of supplementary fat the protein requirement of male turkeys was shown to be higher than for female turkeys (Jensen et al., 1965). In these studies, which were done with a relatively slow growing strain of Broad Breasted Bronze, a protein level of more than 20% appeared to…