Fatty Acid Composition of Diets, Metabolism, and Deposition in Subcutaneous Adipose Tissue of Pasture and Feedlot Finished Cattle

An experiment was conducted to evaluate the effects of pasture finishing versus high-concentrate finishing, over time, on fatty acid metabolism in Angus crossbred (n = 24) beef steers. Ruminal fluid, serum, and adipose tissue biposies 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 high-concentrate diet consisted of corn silage, cracked corn, soybean meal, and a vitamin and mineral supplement. The pasture-finished steers grazed sequentially on triticale (Triticale hexaploide)/annual ryegrass (Lolium multiflorum), alfalfa (Medicago sativa)/orchardgrass (Dactylis glomerata), and a cool-season grass/legume mixture. The high-concentrate diet consisted of 57 % linoleic acid and 7 % linolenic acid (of total fatty acids). The pasture forages contained an average 9 % linoleic acid and 66 % linolenic acid (of total fatty acids). Adipose tissue concentrations of 18:2 cis-9, trans-11 CLA were higher (P < 0.05) in the pasture-finished steers than high-concentrate finished steers. Concentrations of 18:2 cis-9, trans-11 CLA declined in the high-concentrate finished steers (P < 0.05) from d 0 to 28 and d 28 to 84. In the pasture-finished steers concentrations peaked (P < 0.10) on d 28, and remained high throughout the duration of the study. Concentrations of linolenic acid were higher (P < 0.05) in adipose tissue, ruminal fluid, and serum of the pasture-finished steers, compared to the high-concentrate finished steers. In the pasture-finished steers linolenic acid concentrations peaked (P < 0.05) on d 28, and remained high throughout the study. Concentrations of linolenic acid gradually decreased (P < 0.05) over time within the high-concentrate finished steers. Thus, it appears that only a short time is needed to alter the omega-3 and CLA composition of adipose tissue in cattle finished on pasture.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Animal and Poultry Sciences

Department dc:contributor.department

Animal and Poultry Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2005

Author dc:creator

• Guay, Jennifer Fincham

Chair dc:contributor.committeechair

• Fontenot, Joseph P.

Committee members dc:contributor.committeemember

• Neel, James P. S.
• Abaye, Azenegashe Ozzie
• Wahlberg, Mark L.
• Clapham, William M.
• Herbein, Joseph H. Jr.
• Swecker, William S. Jr.

• Fatty Acids
• Conjugated Linoleic Acid
• Pasture-finished beef
• Time on Feed

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-04152005-101906

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/26872