Three experiments were conducted to contrast the effect of dissimilar lipid sources on broiler chicken metabolism. In Experiment 1, the nitrogen-corrected apparent metabolizable energy values (AME_n) of soybean oil (SBO) and hydrogenated soybean oil (HSBO) were determined. Trans monoenes, present only in HSBO, comprised 41% of total fatty acids. The AME_n contents of SBO and HSBO were determined to be 8,739 and 7,657 kcal/kg, respectively. The influence of dietary fatty acids on the lipid composition of the intestinal brush border membrane (BBM) was studied in Experiment 2. Beginning at hatch, chickens were provided isocaloric diets, identified as being either a minimal-lipid (1% 18:2n6) basal diet (ML) or one of three diets in which one-sixth of the caloric content of the basal diet was replaced by oils high in either polyunsaturates (HP), saturates (HS), or trans (HT) monoenes. The BBM alkaline phosphatase specific activity was greater in chickens fed HT than in those fed ML, HP, and HS. The BBM concentrations of palmitic, stearic, and oleic acids were not affected by treatment. Less linoleate (P<.06) and linolenate (P<.05) were present in the BBM of chickens receiving HT and HS than in those fed ML and HP. Arachidonate was present in greater concentrations when birds were fed ML, HP, and HS than when fed HT. Trans isomers were present only in the BBM from chickens fed HT. In Experiment 3, the effects of supplemental dietary lipidS on 1) the lipid composition of intestinal tissue and 2) the in vitro absorptive rate of differing dietary nutrients were studied. Diets similar to those in Experiment 2 were offered to broiler chicks from hatch to 28 days of age. Intestinal membrane concentrations of palmitic and oleic acids were not affected by dietary treatment. Chickens receiving the HSBO or the palm oil diet had less intestinal 18:0, 18:2n6, 18:3n3, and 20:4n6 than did those offered SBO or the control diet. In all treatments, linoleate and oleate were absorbed at a faster rate than stearate across all treatments. The in vitro uptake rates of oleate and linoleate were not affected by dietary treatment. Stearate and glucose uptakes were reduced in chickens fed HSBO or palm oil compared to those offered either the control diet or SBO diet. / Ph. D.