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Title: Fatty acids of Beef Longissimus Muscle

item DINH, THU - Texas Tech University
item BLANTON, JR., JOHN - Samuel Roberts Noble Foundation, Inc
item RILEY, DAVID - Texas A&M Agrilife
item Chase, Chadwick - Chad
item Coleman, Samuel
item Phillips, William
item BROOKS, J - Texas Tech University
item MILLER, MARK - Texas Tech University
item THOMPSON, LESLIE - Texas Tech University

Submitted to: American Society of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2009
Publication Date: 2/18/2010
Citation: Dinh, T., Blanton, Jr., J., Riley, D.G., Chase, C.C., Coleman, S.W., Phillips, W.A., Brooks, J., Miller, M., Thompson, L. 2010. Intramuscular fat and fatty acid composition of longissimus muscle from divergent pure breeds of cattle. American Society of Animal Science. Journal of Animal Science. 88:756-766. doi10.2527/JAS2009-1951.

Interpretive Summary: Beef marbling is one of the most important factors in determining beef quality and carcass value. Marbling characteristics are affected and characterized by fatty acid composition which affects fat melting attributes and can cause variation in firmness or appearance of intramuscular fat, or marbling score. Moreover, fatty acid (FA) composition can contribute to oxidative susceptibility, cooked flavor, and nutritional value of beef. It has become evident that genetic makeup may affect the quantitative and qualitative fat depositions. In the warm regions of the U.S., the most adapted breeds of cattle are American Brahman, a Bos indicus (Zebu) breed, or breeds developed by crossing typical English or Continental Bos taurus breeds with Brahman. The Romosinuano is a tropically adopted, Criollo beef breed native to Colombia with its origin in the Sinu river region of northern Columbia. This study was designed to determine the differences in intramuscular fat composition among Angus (AN), Brahman (BR), and Romosinuano (RM) purebreds, focusing on FA composition of longissimus muscle and its relationship to Intramuscular fat content. The results showed significant differences among AN, BR, and RM purebred cattle in both fatness and fat composition. Crude fat determination revealed that longissimus muscle from Angus purebred cattle had the highest amount of intramuscular fat. intramuscular fat of longissimus muscle from Angus and Brahman contained higher percentage of total saturated fatty acids, whereas that from Romosinuano had the highest percentage of total poly-unsaturated fatty acids. The percentage of total mono-unsaturated fatty acids was similar among the three breeds. The gravimetric calculation, a measure of actual fatty acid concentration, showed higher concentrations of all categories of fatty acids (saturated, mono-unsaturated, and poly-unsaturated) in the longissimus muscle from AN cattle as compared to that from either BR or RM cattle. Interestingly, BR purebreds had the lowest poly-unsaturated fatty acid concentration although their average intramuscular fat content was found to be similar to that of RM. Regardless of breed, the mono-unsaturated proportion was always highest (47.02% - 47.90%) while poly-unsaturated fatty acid proportion was the lowest contributor to fatty acid composition (1.51 mg/g to 2.36 mg/g and 4.32% to 8.25%). Beef longissimus muscle fatty acid composition was characterized by palmitic and oleic acids being the most abundant fatty acids. These traits have been found to be relatively heritable and could be used in developing breeding management strategies. These results will also help elucidate the effects of crossbreeding strategies on fatty acid composition, beef flavor, fat oxidation, and ultimately retail shelf-life.

Technical Abstract: The objective of this study was to compare the fatty acid (FA) composition of the intramuscular (i.m. fat of the longissimus muscle (LM) from three divergent breeds of cattle: Angus (AN, n=9), Brahman (BR, n=7), and Romosinuano (RM, n=11). Cattle were blocked by breed and finished within an average of 128.9 d prior to harvest in two consecutive years. Longissimus muscle samples were collected from each carcass between the 10th and 13th ribs, trimmed of external fat, frozen in liquid nitrogen, homogenized, and utilized for fat extraction using the modified Folch procedure. Extracted fat was analyzed for fatty acids using a GLC system with an HP-88 capillary column. Fatty acid composition was expressed using both a normalized percentage (%) and gravimetric calculation (mg/g of fresh muscle tissue), in relation to degree of saturation, which was determined using saturation index (SI, ratio of total SFA to total unsaturated fatty acids). Crude fat determination revealed that LM from AN purebred cattle had the highest amount of i.m. fat (7.08%), P =0.001). While i.m. fat of LM< from RM contained a lower percentage of total SFA (P=0.002) as compared to only that of LM from AN, it had the highest percentage of total PUFA (P< 0.001 and P= 0.020). the percentage of total MUFA was similar among the three breeds (P=0.675). The gravimetric calculation, a measure of actual FA Concentration, showed significantly higher concentrations of SFA 26.67 mg/g) and FUFA (26.50mg/g), and PUFA (2.37mg/g) in LM from AN cattle, as compared to LM from BR and RM cattle (P<0.001) in the LM, although their i.m. fat content was found to be similar to that of RM (P=0.924). regardless of breed, the FUFA proportion was always the highest (47.58%. P<0.005) while PUFA was the lowest contributor to FA composition (1.49 mg/g tp 2.37 mg/g and 4.36% to 8.78%. {<0.001). Beef LM fatty acid composition was characterized by palmitic and oleic acids being the most abundant fatty acids (P<0.001). These results suggested a genetic variation in FA synthesis and deposition among breeds that influenced both marbling and its composition.