Pasture- and feedlot-finished beef steers (n = 48) were supplemented with 25-hydroxyvitamin D3 (25-OH D3) on d 7 prior to harvest. The longissimus (LM), semimembranosus (SM), and gracilis (GR) muscles were collected after harvest for evaluation of lipid percentage, fatty acid profiles, and fatty acid content. Lipid percentages did not differ between pasture- and feedlot-finished steers. Muscles, however, did differ in lipid percentage with the GR having the least lipid followed by the SM and LM. Fatty acid profiles differed as a result of dietary treatment and also were different among muscles. Monounsaturated fatty acids (MUFA) were greater in steaks from feedlotfinished steers than pasture-finished steers. Polyunsaturated fatty acids (PUFA) were greatest in the GR muscle as compared with the LM and SM. Conjugated linoleic acid (CLA) was greater in the longissimus and semimembranosus of pasture-finished steers than other muscles and feedlot-finished steers. Concentrations of C18:3n3 were also greater in the LM of pasture-finished steers. Data for fatty acid content were similar to those for fatty acid profiles, indicating that 100 g of tissue would contain 14 mg of CLA and that the LM had the greatest total content of saturated fatty acids (SFA), MUFA, and PUFA.
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