THE RESPONSE OF BROILER-CHICKENS AND TURKEY POULTS TO DIETARY ENERGY SUPPLIED EITHER BY FAT OR CARBOHYDRATES

The efficacy of fat and carbohydrates as energy sources was compared i n 1- to 4- to 7-wk-old broiler chickens and in 16-19-wk-old turkeys. A n increase in dietary energy by carbohydrate was made by a graded repl acement of wheat bran by wheat. Energy was increased by fat through a graded replacement of soybean hulls with refined soybean oil. In the e xperiments with broiler chickens, the feed efficiency responses to add ed energy were observed within the entire range of dietary energy test ed, with no significant differences between the responses to carbohydr ate and fat as energy supplements. The growth response to energy from either source appeared to be characterized by diminishing returns in t he chicken. In the 16- to 19-wk-old turkeys, the growth and feed effic iency responses were linear within the range from 2,650 to 3,250 kcal/ kg. In chickens and in turkeys, the growth and feed efficiency respons es to energy supplied by fat were indistinguishable from those of carb ohydrates. In chickens, the fractions of abdominal fat and pectoral mu scle were not affected significantly by the energy density and source.