A Research Note Conjugated Linoleic Acid Concentration in Semimembranosus Muscle of Grass‐ and Grain‐fed and Zeranol‐implanted Beef Cattle¹

Conjugated linoleic acid (CLA) is a potential anticarcinogen, found in higher concentration in ruminant than in nonruminant products. The concentration of the biologically active 9 cis, 11 trans CLA in semimembranosus muscle from cattle on pasture (without added grain, 7.4 mg/g fat) was significantly higher (p<0.05) than in grain on grass fed (5.1 mg/g fat) and implanted animals (5.2 mg/g fat). Among the other polyunsaturated fatty acids, linolenic and docosahexaenoic acid were higher (p<0.05) in grass‐fed animals. The lower linoleic acid concentration (23.2 mg/g fat) in grass‐fed cattle compared to the grain on grass fed (26.6 mg/g fat) and implanted (27.5 mg/g fat) animals may result from conversion to CLA. The type of feed could thus be manipulated to increase the levels of anticarcinogenic CLA in beef.