Utilization of different fats and oils by adult chickens as a source of energy, lipid and fatty acids

Sixty adult Warren roosters approximately 1 year old, randomized in individual cages, were fed a basal diet with or without 4% added fat. Nine fats and oils were evaluated: tallow (T1 and T2); tallow + soybean acid oil (50:50, TSAO); palm oil (PO); palm oil + soybean acid oil (50:50, PSAO); soybean acid oil (SAO); lard (L); soybean oil (SO); and linseed oil (LO). Soybean lecithin was included at 50 g kg-1 in T2. Experimental diets were evaluated for apparent fat availability (AFA), apparent availability of individual fatty acid (AAFA) and apparent metabolizable energy (AME). The AFA and AAFA values for added fats and oils were derived from those obtained for the basal diet and those obtained for the fat-supplemented diets, by difference, assuming the utilization of fat and fatty acid in the basal diet to be constant. The AME values of added fats and oils were calculated as the product of their AFA values and their gross energy values. In addition, the AME of added fats was calculated by substitution from the AME values of the basal diet and the fat-supplemented diets. The AFA and AME of added fats and oils ranged from 873 to 1013 g kg-1 and 33.5 to 40.2 MJ kg-1, respectively. The addition of soybean lecithin to tallow did not affect the nutritive value of this animal fat. The nutritive value of added fats was more influenced by their free fatty acid content (FFA) and non-nutritive fraction than by their degree of saturation. SAO, with high free fatty acids and unsaponifiable contents, resulted in the lowest values for AME and AFA, but both measurements increased significantly when it was blended with T1 or PO. The AME values of experimental diets supplemented with different fats and oils were equivalent.