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Title: EFFECTS OF FORAGE SPECIES ON FATTY ACID COMPOSITION OF BEEF LONGISSIMUS MUSCLE FROM FORAGE-FINISHED BEEF

Author
item Duckett, S
item Pavan, E
item Sonon, R
item Neel, James - Jim
item Fontenot, J
item Clapham, William

Submitted to: Journal of Animal Science
Publication Type: Proceedings
Publication Acceptance Date: 2/7/2006
Publication Date: 7/8/2006
Citation: Duckett, S.K., Pavan, E., Sonon, R.N., Neel, J.P., Fontenot, J.P., Clapham, W.M. 2006. Effects of forage species on fatty acid composition of beef longissimus muscle from forage-finished beef. Journal of Animal Science. 84(1):387.

Interpretive Summary:

Technical Abstract: Forty-seven Angus-crossbred steers were used to evaluate the effects of forage species grazed in the last 41 d of the finishing period on rib composition, color, and palatability in forage-finished beef and compared to traditional high concentrate finished. Steers grazed naturalized pastures (bluegrass/white clover) for 93 d and then grazed alfalfa (AL; n 12), pearl millet (PM; n = 12), or naturalized pastures (NP; n = 12) pastures for the final 41 d of finishing. Steers (n = 11) were also finished on a high concentrate diet (C) for 134 d. Data were analyzed with finishing treatment in the model. Total lipid content of longissimus muscle was 57% lower (P < 0.01) for forage-finished than C with no differences among forage species. Saturated fatty acid percentage was higher (P < 0.05) for AL than PM and C due to greater (P< 0.05) concentrations of stearic acid, Monounsaturated fatty acid percentage was higher (P < 0.05) for C than all forage-finished treatments indicating greater activity of delta-9 desaturase enzyme. Omega-6 fatty acid concentration did not differ among treatments. Omèga-3 fatty acid concentration was higher (P < 0.05) for AL, PM and NA than C. Linolenic acid percentage was greater (P < 0.05) for AL than PM and NA, which were greater (P < 0.05) than C. The ratio of omega-6 to omega-3 fatty acids was lower (P < 0.05), hence more desirable from a human health standpoint, for forage-finished than C (1.32 vs. 6.37, respectively). Trans-il vaccenic acid concentration was greater (P < 0.05) for forage-finished than C; whereas, trans-lO octadecenoic acid concentration was greater (P < 0.05) for C than forage-finished. The cis-9 trans-il isomer of conjugated linoleic acid concentration was 150% greater (P < 0.05) for forage-finished than C. Overall, forage-finished beef was leaner and contained greater concentrations of desirable fatty acids compared to concentrate finished. However, only minor changes in fatty acid composition as related to finishing on different forage species were observed.