Three experiments were conducted to determine how dietary lipid sources influence lipid and polyunsaturated fatty acid (PUFA) metabolism when fed to young, growing chickens. In the first experiment, commercial meat-type chickens were fed one of four dietary lipids: 1) linseed oil (LO); 2) menhaden oil (MO); 3) soybean oil (SBO); or 4) chicken fat (CF). Chickens fed the polyunsaturated lipids, LO, MO, and SBO all had similar very low density lipoprotein + low density lipoprotein (VLDL + LDL) triacylglycerol concentrations which were lower than those for chickens fed CF. Tissue lipids from chickens fed LO contained more 20:5n3 compared with those fed SBO or CF. The amounts of 20:5n3 in tissues from chickens fed LO approached those found in tissues from chickens fed MO. Tissue lipids from LO and MO treatments exhibited decreased 20:4n6 concentrations compared with SBO or CF treatments. The data indicate that dietary n-3 lipid sources influence the fatty acid compositions of tissues and can be effectively used to enrich edible chicken tissues. The second experiment examined the effects of varying combinations of CF and MO on plasma triacylglycerols in broiler chickens. As the amount of dietary n-3 fatty acids and the polyunsaturate:saturate ratio increased, the concentration of triacylglycerols in plasma and the plasma VLDL + LDL fraction decreased. On the other hand, plasma triacylglycerol levels increased as the dietary n-6 fatty acids increased. The dietary n-3 fatty acids in the MO treatment led to higher levels of PUFA in the tissues evaluated. In the third experiment, female chickens from two genetic lines, high body weight (HW) and low body weight (LW), were fed SBO (rich in n-6 polyunsaturates) or MO (rich in n-3 polyunsaturates). The amounts of triacylglycerols in the plasma VLDL + LDL fractions were elevated in the LW chickens compared with the HW groups. Amounts of 18:1 isomers and total monounsaturates were highest in the livers and hearts of HW chickens. Feeding MO enriched the plasma, liver and heart tissues with n-3 polyunsaturates in both genetic lines. Plasma triacylglycerol concentrations were decreased in chickens fed MO at 56, but not at 84 days of age. The data suggest differences in lipid metabolism between the HW and LW lines which were not greatly affected by dietary n-6 or n-3 polyunsaturated fatty acids. / Ph. D.