The Energy Value of Fats and Fatty Acids for Chicks

IT HAS been shown by Donaldson et al. (1957) and Rand et al. (1958) that the chick can utilize high levels of fat as a source of energy. However, there are significant differences between fats in the amount of energy which is available to the chick (Carver et al., 1955; Sunde, 1956; March and Biely, 1957). The magnitude of this difference was quantitatively demonstrated by Renner and Hill (1958) who determined the metabolizable energy value and apparent digestibility of a variety of fats ranging in iodine values from 44 to 169. These latter investigators also found that fatty acid mixtures derived from the hydrolysis of beef tallow, lard and soybean oil were much lower in metabolizable energy value than the respective intact triglycerides. At the same time they showed that both palmitic and stearic acids when fed individually were completely unutilized by the chick and attributed the poor utilization of…