No abstract

Lipid was extracted from the biceps femoris and longissimus dorsi muscles of pronghorn antelope, mule deer, elk, range steers and feedlot steers after being trimmed of subcutaneous fat and connective tissue. Muscles of game animals contained more phospholipids than those of steers and muscles of antelope and deer were higher in cholesterol. Muscles of feedlot steers contained the most total lipid and triglycerides. Polyunsaturated lipid was highest in muscles of game animals due to higher levels of phospholipids. Polyunsaturated:saturated lipid ratios were highest in muscles of game animals followed by those in the muscles of range steers and lastly by those in the muscles of feedlot steers. In addition, the proporation of 18:3, an omega‐3 polyunsaturated fatty acid, in total polyunsaturated acids measured were higher in the muscles of game animals and range steers than in those of feedlot steers.

Longissimus muscle of feedlot steers contained less moisture and more triglycerides (TG) but similar amounts of cholesterol and lipid phosphorus when compared to muscle of range steers. A 100-g portion of the muscle from feedlot steers provided more of all fatty acids analyzed except iso-and anteiso-tridecanoic and pentadecanoic acids (br 13:0, br 15:O) and octadecatrienoic acid (18:3). Structures of the intramuscular TG were not influenced by dietary treatment. Medium chain saturated acids (1O:O to 15:O) were distributed throughout all 3 positions, 16:0 predominated in the sn-1 position, 18:0 and 20:0 in the sn-1 and ~2-3 positions. Br 13:0 and br 15:0 predominated in the sn-2 position and were essentially absent from the sn-3 position. Monounsaturated acids, with the exception of trans octadecenoic acid (tram 18:1), were found mainly in the sn-2 and sn-3 positions. Trans 18:l predominated in the sn-1 and sn-3 positions thereby resembling a long chain saturated acid, Octadecadienoic acid (18:2) and 18:3 were about equally divided between positions m-2 and sn-3. Tram 18: 1 comprised 1.9 and 1.3% of total intramuscular fatty acids from range and feedlot steers, respectively. The structures of intramuscular TG, with respect to 18:2 and saturated acids, did not resemble those of native peanut oil which has been reported to be more atherogenic than randomized peanut oil.

Softness of subcutaneous fat from ram lambs fed high corn silage or high corn diets varied within each dietary group, but, overall, fat from lambs fed the high corn-silage was harder. Consistent decreases in stearic acid and increases in branched-chain and odd-numbered acids accompanied increases in fat softness both within each dietary group and between dietary groups. Results of this study suggest that the synthesis of even-numbered, saturated acids is decreased as the fat becomes softer. Conversion of the high melting, even-numbered, saturated stearic acid to oleic acid, the major acid found in the subcutaneous fat, causes considerable decreases in stearic acid with consequent increase in softness. Increases in linoleic and linolenic acids in fat from the high corn dietary group were not major factors in fat softness. Low levels of elaidic acid were found in all fat samples but the presence of this fruns-acid was not involved in fat hardness.

Subcutaneous and intramuscular lipids from feedlot-and grass-fed ewes were studied to determine if diet would influence fatty acid composition of these older animals. Subcutaneous lipid of ewes from the feedlot-fed group contained more 4-methyl branched acids, less is0 and anteiso branched acids, less stearic acid and more octadecenoic acid than grassfed ewes. Only small amounts of medium chain acids (10-15 carbons) were noted in longissimus muscle lipids from both dietary groups and essentially all of them were in the triglycerides. Lipids in longissimus muscle of feedlot ewes contained more monounsaturated and less polyunsaturated acids and this was due to higher levels of triglycerides in longissimus lipid of feedlot-fed ewes. Approximately three times as much high melting stearic acid was present i n subcutaneous lipid of both dietary groups of ewes as has been noted in subcutaneous lipid of lambs. Reduction of high melting stearic acid in mutton fat by a short grain feeding period should make mutton more acceptable.

Summary Tests with 24 substituted phenols showed that position was more important than the nature of the alkyl group in influencing antioxidant potency for lard. The most active compound tested was 2,6‐di‐tert‐butyl‐4‐methylphenol.

Marrow from cervical, lumbar and femur bones-of 5 steers and 5 cows fed only on native range (grass fed) and 5 steers and 5 cows fed a finishing ration (grain fed) was analyzed for cholesterol content. The cholesterol content of the marrow was significantly different when diet or anatomical locations were compared. Bovine marrow from grass-fed animals averaged 119.6 mg/lOOg and marrow from grain-fed animals averaged 150.6 mg/lOOg marrow. The cholesterol content of marrow from the cervical, lumbar, and femur was 190.1, 124.1, and 91.0 mg/lOOg marrow, respectively. Mechanically deboned meat (MDM) and beef lean had a mean cholesterol content of 153.3 and 50.9 mg/lOOg tissue. Spinal cord material in MDM can account for the increased concentration of cholesterol in some MDM samples over the values for lean and marrow.

Broiling of loin and round steaks from concentrate-fed and pasturegrazed steers had no significant effects upon levels of intramuscular triglycerides or cholesterol when expressed on a freeze-dry basis. Broiling did cause increases in phospholipids and free fatty acids. Broiling did not influence fatty acid compositions of triglycerides, polar lipids and free fatty acids. Loin steaks contained more triglycerides and free fatty acids and less phospholipids and cholesterol than round steaks. Increases in intramuscular triglycerides were not accompanied by increases in cholesterol or phospholipids. Polyunsaturated/ saturated acid ratios and levels of linolenic acid, an n-3 acid, were highest in steaks from steers that had grazed pastures.