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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2008-1277v1 87/10/3259    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 Fincham, J. R. Articles by Notter, D. R. PubMed PubMed Citation Articles by Fincham, J. R. Articles by Notter, D. R.

Fatty acid metabolism and deposition in subcutaneous adipose tissue of pasture- and feedlot-finished cattle¹

J. R. Fincham^*,2, J. P. Fontenot^*,3, W. S. Swecker, J. H. Herbein, J. P. S. Neel, G. Scaglia^*,4, W. M. Clapham and D. R. Notter^*

^* Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061; and Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg 24061; and Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061; and ARS-USDA, Appalachian Farming Systems Research Center, Beaver, WV 25813

³ Corresponding author: cajunjoe{at}vt.edu

An experiment was conducted to evaluate the effects of pasture finishing versus feedlot finishing, over time, on fatty acid metabolism in Angus crossbred steers (n = 24). Ruminal fluid, serum, and adipose tissue biopsies were obtained on d 0, 28, 84, and 140. Pasture forages and diet ingredient samples were obtained at 14-d intervals to determine nutritive value and fatty acid composition. The feedlot diet consisted of corn silage, cracked corn grain, soybean meal, and a vitamin and mineral supplement. The pasture-finished steers grazed sequentially on triticale (x Triticosecale rimpaui)/annual ryegrass (Lolium multiflorum), alfalfa (Medicago sativa)/orchardgrass (Dactylis glomerata), and a cool-season grass/legume mixture. The feedlot diet contained an average of 57% of total fatty acids as linoleic acid and 2% as linolenic acid. The pasture forages contained 9% of total fatty acids as linoleic acid and 66% as linolenic acid. Concentrations (% of total fatty acids) of linolenic acid were greater (P < 0.05) in ruminal fluid, serum, and adipose tissue of the pasture-finished steers, compared with the feedlot-finished steers. Concentrations (% of total fatty acids) of cis-9, trans-11 CLA were greater (P < 0.05) in adipose tissue of the pasture-finished steers than feedlot-finished steers. Concentrations of cis-9, trans-11 CLA in adipose tissue declined (P < 0.05) in the feedlot-finished steers from d 0 to 28 to 84. In the pasture-finished steers, concentrations of cis-9, trans-11 CLA in adipose tissue (mg/g of tissue) peaked (P < 0.05) on d 28 and remained elevated (ranged from 9.91 to 12.80 mg/g of tissue) throughout the duration of the study. In the pasture-finished steers, linolenic acid concentrations tended to peak (P = 0.07) on d 28 and remained elevated (ranged from 0.64 to 0.80% of total fatty acids) throughout the study. It appears that only a short time is needed to alter the n-3 and CLA composition of adipose tissue in cattle finished on pasture.

Key Words: beef cattle • conjugated linoleic acid • fatty acid • pasture-finishing • time on feed