Variations in the iodine value of fats from the fatty, muscular and bone tissues of mature Romney ewes

Abstract

1. Investigations on the fats from different tissues of forty-eight Romney ewes have shown that the iodine numbers of the fats cover a wide range from 32·7 for a perinephric fat to 83·7 for the fat from a metacarpal bone, while the percentage fat varies from as low as 3·8 in a longissimus dorsi muscle sample up to as high as 95·5 in a perinephric fat sample.2. The mean iodine values of the fat and percentage fat respectively in the tissues examined were as follows: perinephric, 39·8, 88·1; loin subcutaneous, 41·7, 80·9; loin intermuscular, 44·4, 71·4; longissimus dorsi muscle, 53·1, 7·7; femur, 45·1, 39·8; tibia-tarsus, 54·3, 30·6 and metacarpus, 79·9, 24·3.3. In the carcass tissues the muscle fat was significantly higher in iodine value than the fat from the fatty tissues. In the long bones analysed, the fats from the metacarpus had a highly significantly greater iodine value than was found for the other bones or carcass tissues. The fat from the tibia-tarsus was comparable in iodine value to that of the muscle tissue while the iodine value of the fat from the femur approached that from a fatty tissue.4. A distinctive feature of the fats examined was their variability in iodine value. The values varied between animals by 15·3 units for perinephric fat, by 13·0 units for subcutaneous fat, by 16·9 units for intermuscular fat and by 12·4 units for muscle fat.5. The present results for the iodine values of the fats of Romney ewes generally agree with those obtained by Callow (1958) for Suffolk lambs. However, whereas in Suffolk sheep in accordance with the temperature theory of Henriques & Hansen (1901) the subcutaneous fats have higher iodine values than do the intermuscular fats, in the Romney sheep studied the reverse holds.