Independent Effects of Dietary Metabolizable Energy and Protein Concentrations on Performance and Carcass Characteristics of Tom Turkeys

Abstract

An experiment was conducted to determine the independent and interaction effects of dietary metabolizable energy (ME) and protein concentrations on performance of Large White toms from 9 to 20 weeks of age. Diet treatments consisted of a complete factorial arrangement of three ME concentrations and three protein concentrations within each age interval (9 to 12, 12 to 16, and 16 to 20 weeks). The different ME concentrations were obtained by using an animal-vegetable fat blend at 0, 4, or 8% of the diets. Dietary protein levels tested provided approximately 88, 97, or 107% of those recommended by National Research Council (1977) for each age interval. The ME concentrations represented 95, 100, or 105% of those used most frequently in commercial feeding programs in the central United States.Dietary ME and protein concentrations had significant (P<.03) independent effects on turkey performance. As each diet variable was increased, gain in body weight and feed efficiency were improved. Increasing dietary ME reduced the amount of protein consumed per kilogram of gain but not the ME consumed per kilogram of gain. Protein consumed per kilogram gain increased as dietary protein increased, while ME intake per kilogram gain decreased. Carcass composition and parts yield of the carcass were affected only slightly by dietary ME and protein concentration. No significant (P>.10) interaction effects of dietary ME and protein were detected, except in the instance of absolute quantity of carcass protein (P<.07). Data from this experiment and results of other research suggest that the use of “optimum ME-to-protein ratios” as a restriction in formulation of turkey diets may be inappropriate and that greater emphasis should be placed on the nutritional and economic implications of the independent effects of ME and protein on rate of growth and feed efficiency.