Varying fat and protein in diets of growing large white turkeys

Two series of three consecutive 4-week experiments with a total of 1,370 Large White turkeys between 8 and 20 weeks of age were conducted to determine the effects of varying levels of dietary fat and protein on body weight gain and feed efficiency. Diets containing 0, 5, and 10% added fat and 18, 20, 22, and 24% protein in a 3 X 4 factorial were each fed to a total of three pens of males and three pens of females. At the end of each 4-week period, the turkeys were rerandomized to form 12 new equivalent groups, and similar diets with 2% less protein were fed. As part of this study, two fats, varying in fatty acid composition, were also compared but found not to affect significantly body weight gain or feed efficiency. Interaction effects of fat and protein on body weight gain, feed consumption, or feed efficiency were not significant. Body weight gain increased .5, .6, and 1.1%, feed consumption decreased 1.1, 1.0, and .9%, and feed efficiency increased 1.7, 1.8, and 2.2% for each 1% added fat during the 8 to 12-, 12 to 16-, and 16 to 20-week periods, respectively. The greater-than-expected increase in feed efficiency from added fat to diets of older turkeys is postulated to be due to stimulated feed consumption and body weight gain rather than to an extra caloric content of fat per se.