Title page for ETD etd-04152005-101906

Type of Document Dissertation
Author Guay, Jennifer Fincham
URN etd-04152005-101906
Title Fatty Acid Composition of Diets, Metabolism, and Deposition in Subcutaneous Adipose Tissue of Pasture and Feedlot Finished Cattle
Degree PhD
Department Animal and Poultry Sciences
Advisory Committee
Advisor Name Title
Fontenot, Joseph P. Committee Chair
Abaye, Azenegashe Ozzie Committee Member
Clapham, William M. Committee Member
Herbein, Joseph H. Jr. Committee Member
Neel, James P. S. Committee Member
Swecker, William S. Jr. Committee Member
Wahlberg, Mark L. Committee Member
  • Fatty Acids
  • Conjugated Linoleic Acid
  • Pasture-finished beef
  • Time on Feed
Date of Defense 2005-04-06
Availability unrestricted
    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.

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