| Popis: |
Fatty acids were evaluated to characterize lipid profiles of beef from 3 feeding programs: New Zealand (NZ) fodder beet (FB), NZ grass/non-FB (NFB), and United States grain. Strip loins were selected within each program based on expected eating quality focusing on marbling, ossification, and pH. Selection resulted in 6 treatments: FB high quality, FB low quality, NFB high quality, NFB low quality, US Top Choice, and US Select. Samples were aged 21 d or 35 d postmortem. A subset of 152 samples (12–13 per treatment combination) were used for fatty acid characterization. Within the polar lipid fraction, US treatments had lower monounsaturated fatty acid (MUFA) and greater polyunsaturated fatty acid (PUFA) than NZ treatments (P < 0.05). Within the neutral lipid fraction, concentrations of total neutral lipids and proportions of saturated fatty acid, MUFA, and PUFA were affected by treatment (P < 0.05). Total neutral lipids were greatest in Top Choice (P < 0.05) and greater in FB high quality than all other treatments (P < 0.05). Proportions of satu- rated fatty acid in the neutral lipid fraction were greater in NFB treatments than US treatments (P < 0.05); FB treatments were intermediate. Proportions of MUFA were greatest in Top Choice (P < 0.05). Proportions of PUFA were greatest (P < 0.05) in Select, greater in Top Choice than all NZ treatments (P < 0.05), and greater in NFB treatments than FB treatments (P < 0.05). No interactions occurred for any groups of fatty acids in either fraction ( P > 0.05), and aging did not affect fatty acid composition. Lipid profiles were impacted by finishing diet; however, most differences were between US grain-fed beef and NZ treatments—with limited differences between FB and NFB samples—when product was selected based on quality descriptors. Therefore, FB could be substituted for grass forages to sustain the NZ beef industry through winter months and limit seasonality without detrimental effects on product quality. |
