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This Article Full Text (PDF) All Versions of this Article: jas.2009-1850v1 87/9/2961    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Duckett, S. K. Articles by Clapham, W. M. PubMed PubMed Citation Articles by Duckett, S. K. Articles by Clapham, W. M.

Effects of winter stocker growth rate and finishing system on: III. Tissue proximate, fatty acid, vitamin, and cholesterol content

S. K. Duckett^*, J. P. S. Neel, J. P. Fontenot and W. M. Clapham

^* Clemson University, Clemson, SC , ARS, USDA, Beaver, WV Virginia Polytechnic Institute and State University, Blacksburg, VA

sducket{at}clemson.edu

Abstract

Angus-cross steers (n = 198; 270 kg; 8 mo) were used in a three-year study to assess the effects of winter stocker growth rate and finishing system on LM proximate, fatty acid, cholesterol, vitamin, and mineral composition. During the winter months (December to April), steers were randomly allotted to three stocker growth rates: low (0.23 kg/d; LOW), medium (0.45 kg/d; MED), or high (0.68 kg/d; HIGH). At the completion of the stockering phase, steers were allotted randomly within each stocker growth rate to either a high concentrate (CONC) or pasture (PAST) finishing system and finished to an equal time endpoint. Winter stocker growth rate did not alter (P > 0.05) proximate, cholesterol, or vitamin content of the LM. All interactions among winter stocker growth rate and finishing system were non-significant indicating that supplementation systems during winter stocker period did not influence beef composition after finishing on PAST or CONC. Finishing steers on CONC lowered (P < 0.001) moisture content of the LM and increased (P < 0.001) lipid content of the LM. Protein, ash, and cholesterol content of the LM did not differ (P > 0.05) between finishing systems. -Tocopherol and β-carotene content of the LM were 288% and 54% higher, respectively, for PAST finished cattle than CONC. B-vitamins, thiamin and riboflavin, were also present in higher (P = 0.001) concentrations for PAST than CONC. Calcium, Mg and K contents of the LM were higher (P < 0.05) for PAST than CONC. Total fatty acid content of the LM was 49% lower for PAST than CONC. Myristoleic, palmitoleic and oleic acid concentrations were all lower (P = 0.001) for PAST than CONC. Trans-10 octadecenoic acid percentage in LM was 97% higher (P = 0.001) for CONC than PAST; conversely, trans-11 vaccenic acid (TVA) percentage in the LM was 90% higher (P = 0.001) for PAST than CONC. Conjugated linoleic acid, cis-9 trans-11 isomer, percentage was higher (P = 0.001) by 117% for PAST than CONC. Linoleic acid (C18:2) concentration did not differ (P > 0.05) among PAST and CONC. Concentrations of all n-3 fatty acids (linolenic acid, EPA, DPA, DHA) were higher (P = 0.01) for PAST than CONC. Total n-6 PUFA percentages were unchanged (P > 0.05) among finishing systems. The ratio of n-6 to n-3 fatty acids was 4.84 for CONC and 1.65 for PAST. Beef from CONC finished has a higher total, saturated and monounsaturated fat content; in contrast, beef from PAST finished has lower total, saturated and monounsaturated fat content with higher contents of n-3 fatty acids and a lower n-6 to n-3 ratio. Beef from PAST finished also has greater contents of B-vitamins and antioxidants (vitamin E and beta-carotene).

Key Words: Beef • Forage • Fatty acids • Proximate