The nutritive value of dietary fats in relation to their chemical composition. Apparent fat availability and metabolizable energy in two-week-old chicks.

Broiler chicks at 2 wk of age were fed the following fats and oils at 4% in a corn-wheat-soybean basal diet: palm oil (PO); tallow (T1 and T2); tallow + soybean oil (50:50, TSO); tallow+acidulated soybean oil soapstock (50:50, TASO); soybean oil (SO); and linseed oil (LO). All of these, with the exception of T1, contained 5% soybean lecithin. The apparent fat availability (AFA) and AME of added fats ranged from 78.8 to 96.0% and from 7.32 to 8.95 kcal/g, respectively. Three fat sources (TSO, SO, and LO) resulted in the highest values for these two measurements, whereas PO, T1, T2, and TASO showed the lowest values. There was no difference for AME of diets among fat-supplemented treatments, regardless of the difference in the nutritive values of the fats and oils tested. The apparent availability of each fatty acid (AAFA) for C16:0, C18:0, C18:1, C18:2, and C18:3 was calculated from the analysis of the diets and excreta collected over a 4-d period. The results of the present study indicated that 2-wk-old chicks utilize TSO, SO, and LO more efficiently than PO, T1, T2, and TASO.