Effects of supplemental rumen-protected conjugated linoleic acid or corn oil in beef cattle on lipid content and palatability

¹ University of Georgia, Athens, GA
² Clemson University, Clemson, SC

^* To whom correspondence should be addressed. E-mail: sducket{at}clemson.edu.

	Abstract

Thirty-six Angus x Hereford heifers were used in a 3 x 2 factorial (3 dietary treatments; 2 supplementation times) to examine the effect of dietary lipid supplementation on lipid oxidation, lipid composition and palatability of ribeye steaks and ground beef. Lipid was supplied to diets as either corn oil or a partially rumen-protected conjugated linoleic acid (CLA) salt for two specific treatment periods of either the final 32 or 60 d on feed, corresponding to the final 89 or 118 d on feed. Following an initial 56-d feeding period (basal diet), heifers were fed one of three dietary treatments (DM basis): 1) basal diet containing 88% concentrate and 12% grass hay (CON), 2) basal diet plus 4% corn oil (OIL), or 3) basal diet plus 2% partially rumen-protected CLA (RPCLA) containing 31% CLA. Heifers were randomly allotted to dietary treatments at initiation of the study and fed individually. At 48 h postmortem, the right forequarter of each carcass was fabricated into retail cuts. Steaks (2.54 cm thick) were obtained from the posterior end of the ribeye roll (NAMP 112) and beef trim was ground for all subsequent analyses. Data were analyzed with treatment, length of supplementation, and the two-way interaction in the model. Dietary treatment did not affect (P > 0.05) lipid oxidation in either ground beef or ribeye steaks. Total trans-octadecenoate fat and trans-10 octadecenoic acid content in ribeye steaks increased (P < 0.05) with RPCLA compared to CON. Total CLA and cis-9 trans-11 isomer of CLA contents in ribeye steaks were unchanged (P > 0.05) by lipid supplementation. In ground beef, RPCLA supplementation increased (P < 0.05) the amount of trans fat and trans-10 octadecenoic acid compared to CON or OIL. Supplementation of RPCLA increased (P < 0.05) the amount of CLA cis-9 trans-11 isomer and total CLA. Lipid supplementation did not alter (P > 0.05) off-flavor ratings in ground beef or ribeye steaks. Supplementation of corn oil increased (P < 0.05) total PUFA content of ribeye steaks compared with CON and RPCLA. Dietary RPCLA supplementation increased the amount of trans fat per serving (85.5 g, broiled) by 110% and 88% in ribeye steak and ground beef, respectively, and CLA cis-9 trans-11 by 58% in ground beef compared to CON. Supplementing OIL or RPCLA resulted in minimal changes in lipid oxidation and sensory attributes of steaks and ground beef.

Key Words: Beef, Conjugated Linoleic Acid, Sensory, Trans fat

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