Fatty acid composition of beef cattle and related changes in the heart muscle of meat consuming animals.

Abstract

Proc. Aust. Soc. Anim. Prod. Vol. 18 FATTY ACID COMPOSITION OF BEEF CATTLE AND RELATED CHANGES IN THE HEART MUSCLE OF MEAT CONSUMING ANIMALS B.D. SIEBERT*, A.Z. CUTHBERTSON* and F.H. BULMAN* The relationship between the incidence of atherosclerosis in humans and the consumption of saturated fat has been appreciated for some years (McDonald 1974). More recently it has been observed also that irregular beating of the heart (arrhythmia), a condition that occurs prior to heart attack, occurs more frequently in experimental animals fed diets containing saturated fat from ruminants than in those fed polyunsaturated fat from plants or fish (McLennan et al. 1988). Although fat red meat contains saturated fats, lean meat is relatively rich-in polyunsaturated fats. Studies in progress at present are , examining experimental animals fed red meat to determine if the fatty acids of lean meat can affect the composition and function of the heart. L Hereford and Simmental cattle were raised indoors on a 1ucerne:oat:feed pellet (1:1:2) diet for two months. Over the last three weeks, one Simmental animal received an abomasal infusion of fish oil. The animals were then slaughtered and meat stripped from the carcasses in a uniform manner (excess fat was discarded). The fat content of meat (minced and mixed) was 4.7% in the Simmental cattle and 18.0% in the Hereford cattle. The fatty acid composition of intramuscular fats was determined in muscle samples taken by biopsy a few days prior to slaughter. There were significant differences in the proportion of the major fatty acid groups (Hereford), lean (Simmental) and lean modified (Simmental with fish oil). The percentage of polyunsaturated fatty acids in the three cattle types were 10.5, 38.4 and 48.1 respectively. When the meat from the cattle was fed to rats (25 per treatment) in a dietary experiment over three months and rat heart muscle analysed for individual fatty a c i d s , significant differences were found in the percentage of polyunsaturates in heart muscle between cattle meat type fed. This was chiefly caused by differences in the level of linoleic acid (carbon chain 18:2), offset to some degree by the longer chain 20:5, 22:s and 22:6 fatty acids, as shown in Table 1. The predominant fatty acid of fish oil, eicosopentanoic acid (20:5), was significantly higher in animals fed meat from fish oil infused cattle. Table 1 Concentration of some polyunsaturated fatty acids in rat heart muscle (% of total) The incidence of arrhythmia in the rat heart was measured prior to sampling over a 40 minute period under anaethesia. Data from those measurements is being assessed at present. The experiment wishes to determine if lean meat can be beneficial in reducing the incidence of heart attack in a society which consumes a high level of saturated fat. MCDONALD, 1-W. (1974). Proc. Aust. Soc. Anim. Prod. 10: 1. d4cLENNAN, P., AEEYWARDENA M. and CHARNOCK J. (1988). Am. Heart J. 116: 709. + CSIRO Division of Human Nutrition, O'Halloran Hill, S.A. 5158. 548