The occurence, physiological effect and possibilities of increasement of conjugated linoleic acid content of meat

Abstract

According to current human dietary principles recommend a reduction in the fat content of the diet and the modification of fatty acid composition of meat, together with the reduction of saturated fatty acid content and an increase of the ratio of polyunsaturated fatty acids and within that increasing the ratio of n-3 fatty acids. The meat with „healthy” fatty acid composition contains low amount of saturated fatty acids; its maintenance of the palmitic acid content is low, the ratio of PUFA/SAFA is higher than 0.45, the ratio of n-6/n-3 PUFA is lower than 4:1 and the fat contains high amount of conjugated linoleic acid. The conjugated linoleic acid concentration of animal products has been getting more and more attention lately. The term conjugated linoleic acid (CLA) refers to isomers of linoleic acid, two (cis-9,trans-11 and trans-10,cis-12 CLA) of the eight variants are natural products and are known to possess biological activity. From the point of human health it has numerous positive effects, which the c9t11 and t10c11 CLA isomers can generated separately or synergistically, they have anticarcinogenic-, antiatherosclerotic-, antidiabetic activities, modulate the immune response, decrease body fat, whilst increasing body protein content. The occurcence of meanly CLA are in ruminants products meat and milk due to specific rumen metabolism, but the adipose tissue of turkey, rat and horse serum can also contain high level of CLA. The CLA content in meat can be influenced by both genetical and enviromental factors. Specific differences can be found among cattle breeds and their CLA concentrations in meat and the effects of major genes on CLA concentration can also be observed. Feeding among the enviromental factors plays an important role. Generally it can be assessed, that the CLA-content in meat increases due to the effect of dietary CLA, but it the forage/concentrate ratio, as well as the content and composition of PUFA should also be considered. For the livestock breeders it is essential to know how the body composition, slaughter value, meat quality could be affected by feeding CLA. In livestock breeds the dietary; CLA generally result in enhancing lean meat content, but increase of the ratio of the meat cuts is different and fatty acid profile also changes, although each breed the latter shows contrary trends.