PROXIMATE, MINERAL AND FATTY-ACID COMPOSITION OF SEMIMEMBRANOSUS AND CARDIAC MUSCLES FROM GRASS-FED AND GRAIN-FED AND ZERANOL-IMPLANTED CATTLE

Chemical composition (proximate, minerals, and fatty acids) of semimem branosus (SM) and cardiac muscle from cattle fed grass (G) and grain o n grass without (GG) or with (GGP) zeranol implant were determined. Th e protein content of SM muscle from GG and GGP cattle was higher (p le ss than or equal to 0.05) while the moisture content was lower (p less than or equal to 0.05) than that from G cattle. The lipid content of cardiac muscle from GG cattle was higher (p less than or equal to 0.05 ) compared to that of G cattle. Grain supplementation (GG and GGP) inc reased the potassium level in SM muscle while a decrease was observed in cardiac muscle. Grain supplementation also increased linoleic acid but decreased polyunsaturated (PUFA) fatty acids in both muscles. Ther e was 3 times more PUFA, particularly linolenic and arachidonic acids, in cardiac muscle than in SM muscle irrespective of the feed type. Th e concentrations of PUFA in SM and cardiac muscle were higher for G ca ttle than for GG and GGP cattle, which could make muscles from G cattl e more prone to oxidation. (C) 1998 Elsevier Science Ltd. All rights r eserved.