Energetic Efficiency of Different Dietary Fats For Growth of Young Chicks

Abstract

Two experiments were conducted to determine the energetic efficiency of diets containing different feed grade fats for the growth of broiler chicks during the finishing period. The fats were added to the basal diets replacing equicaloric amounts of glucose, based upon metabolizable energy (M.E.) thus increasing the energy and nutrient density of the diet but maintaining the same M.E.:nutrient ratios. Fats tested were corn oil, palm oil, acidulated cotton seed soapstock (A.C.S.S.), coconut oil, tallow, poultry fat, and feed grade animal fat (F.G. A.F.). In one trial all fats were tested at one level (11.6%) and in the second trial all fats except A.C.S.S. and coconut oil were tested at levels of 10 and 20%. Body balance was used to partition gross energy (G.E.) consumed in an effort to estimate the heat increment (H.I.) of the fat supplemented diets. H.I. (plus the heat of activity which could not be determined separately by this technique) was consistently lower for the fat supplemented diets than for the low fat controls. H.I. was greater for the diets containing 20% fat than for those containing lower levels. Energy and nutrient intake was higher for all diets containing fats indicating that feed intake is influenced by H.I. of the diet as well as by energy level. Caloric efficiency (G.E. gained/M.E. consumed) was greater with fat-supplemented diets than with low fat controls and was generally greater with 10% fat than with 20%. There were no consistent differences among the fats tested with regard to efficiency of M.E. utilization for growth or fattening except for poultry fat which consistently exhibited greater efficiency of utilization and lower heat increment than other fats. Results with palm oil were inconsistent. All fats except A.C.S.S. and coconut oil improved weight gains of chicks in one trial but not in the other.