The Responses of Chicks to the Dietary Inclusion of Materials which Might be Assumed to Possess Beneficial Extra-caloric Properties

THE USE of animal and vegetable fats in poultry feeds is widespread. Although the major purpose for including fats is to raise energy density there is some evidence that fats may possess beneficial extra-caloric properties. Early evidence of extra-caloric effects such as that reported by Yacowitz (1953), Denton et al. (1954), and Rosenberg et al. (1955) is difficult to interpret as no attempt was made to maintain the calorie:nutrient ratios of control and fat supplemented diets at constant levels. Donaldson et al. (1957), Dam et al. (1959) and Pepper et al. (1960) were able to demonstrate growth stimulating effects of fats even when diets were formulated to have the similar calorie:protein ratios. It is possible that the beneficial effects attributed to fats, when diets of equal calorie: protein ratio are compared, may be explained on the basis of increased nutrient density of the feed. Pepper et al. (1960) found that …