|Neel, James - Jim|
Submitted to: Journal of Animal Science
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2004
Publication Date: 7/1/2004
Citation: Realini, C., Duckett, S.K., Neel, J.P., Fontenot, J.P., Clapham, W.M. 2004. Effect of winter stocker growth rate and finishing diet on beef longissimus fatty acid composition. Proceedings of Journal of Animal Science. 82(1):33. Proceedings of Journal of Dairy Science. 87(1):33.
Technical Abstract: Seventy-two Angus-cross steers were stockered during the winter months at three growth rates (LOW [0.36 kg/d], MED [0.55 kg/d] or HIGH [0.82 kg/d] prior to finishing on pasture (PAST) or corn silage-concentrate diet (CONC) to determine the effects on longissimus muscle fatty acid composition and cholesterol content. Fatty acid profile and cholesterol content of ribeye steaks (12th rib) were determined by GLC. Data were analyzed as a 3 x 2 factorial design with stocker growth rate (LOW, MED, HIGH), finishing diet (PAST or CONC) and two-way interaction in the model. Total lipid content was two-fold greater (P < 0.01) for CONC than PAST, and similar between stocker growth rates. Longissimus muscle from CONC had greater (P < 0.01) proportions of myristoleic, palmitic, palmitoleic, oleic, and total monounsaturated fatty acids than PAST. Saturated fatty acid concentration was greater (P < 0.05) for PAST-LOW than PAST-MED or CONC-HIGH. Trans-11 octadecenoic acid and the cis-9 trans-11 isomer of CLA were 234% and 90% greater (P < 0.01), respectively, for PAST than CONC. Omega-3 fatty acid concentration was 136% greater (P < 0.05) for PAST than CONC due to increases in EPA (C20:5), DPA (C22:5), and DHA (C22:6). For omega-6 fatty acids, PAST-MED had greater (P < 0.05) levels of omega-6 and linoleic acid than PAST-LOW or CONC-HIGH with CONC-LOW and PAST-HIGH being intermediate. The ratio of omega-6 to omega-3 fatty acids was lower (P < 0.05), more desirable from a human health standpoint, for PAST than CONC. Cholesterol content tended (P = 0.06) to be greater for PAST than CONC with no differences among stocker growth rates. Increasing growth rate during winter stockering prior to finishing had only minor influences on longissimus fatty acid composition. Finishing cattle on pasture reduced the total fat content of the longissimus and increased the concentrations of omega-3 fatty acids, CLA and trans-11 octadecenoic acid.