evaluation the cis and trans fatty acid composition in the sheep's fat-tail and meat of baluchi sheep in south khorasan province

introduction the common isoform of fatty acids in animal and herbal lipids are cis fatty acids, however in some sources such as milk and meat of ruminant, the trans fatty acids are more abundant as compared to the plant lipids. the trans fatty acids are very important because they increase the cardiovascular and heart attack. the heart disorders were increased by enhancing the concentration of omega-6 fatty acids and decreasing the concentration of omega-3 fatty acids in ration and blood. the types of pasture cause alter the fatty acid composition of lamb meat. for evaluation of heart function and health of heart, the artherosclosis and thrombogensis were calculated by the concentration of saturated and unsaturated fatty acids. therefore, the subject of this study, evaluation of the fatty acid profiles of sheep's fat-tail and meat at different places of south khorasan province. material and methods five samples of meat and fat-tail from the animal's abattoir in birjand, sarbisheh, asadieh, ferdows, saraian, ghaen, boshroieh and nehbandan cities were collected and frozen (40 samples of meat and fat-tail). the samples were frozen in -80oc freezer. then, the oils were separated and the fatty acids were extracted and methylated by the method of morrison and smith (1964). after that, the 0.5 µl of methylated fatty acids were injected to gas chromatography instruments (varian 4200). the capillary column cpsill 88 was used. the type of each fatty acid was designated with compare to the retention time in the standard peak. the quantity of fatty acids was determined by internal standard method. to evaluation the fatty acids ratio for health, the artherosclosis and thrombogensis indices were calculated based on saturated and unsaturated fatty acids. the data were analyzed by sas software, and the mean were compared by tukey test (α=0.05). results and discussion the analysis of data revealed that the percentage of saturated fatty acids (sfa) was higher at fat-tail as compared to meat of sheeps. the meat had higher mufa and pufa (p<0.05). the previous studies revealed that sfa are undesirable fat and the mufa and pufa are desirable fats. the omega-3 fatty acids were numerically higher in meat. the sheep's fat-tail had higher concentration of omega-6 fatty acids as compared to meat (p<0.05). the ratio of pufa: sfa was higher in meat of sheep. this is very important, because the higher ratio of pufa: sfa could provide better condition for digestion and metabolism of meat in human and improved health and function of heart. this also decreases the heart attack and cardiovascular disease. the omega-6 fatty acids were lower in meat as compared to fat-tail. some of previous studies showed that the type of pastures and the condition of environment could alter the fatty acid composition of sheep's meat and fat-tail. the lower omega-6 fatty acids could also provide a better condition for blood vessels and reduce the serum cholesterol. the omega-6 fatty acids especially arachidonic acids are the main precursors of cholesterol biosynthesis. in addition, higher concentration of trans fatty acids were observed in fat-tail. the concentration of trans fatty acids is higher in ruminant products, because the fat sources were hydrogenated in rumen of ruminant by microbial population, that increases the trans fatty acids and deposition of fatty acids in these animals. this may increase the risk factors and decrease the immune function in sheep. all pastures of south khorasan in different cities change the composition of fatty acid profiles in meat and fat-tail. the data also revealed that fat-tail' sheep had higher index of thrombogenecity; however, the arthrogencity index was the same at meat and fat-tail. this indicates that fatty acids profile of sheep's meat and fat-tail are very important for the performance and immune system of sheep and its effect on the health of meat consumers. conclusion this study revealed that sheep's meat had better fatty acids profiles as compared to fat-tail. the meat has higher ratio of pufa/sfa and lower concentration of omega- fatty acids and the sheep's fat-tails had higher concentration of trans fatty acids and athrogencity index. therefore the sheep meat may have a better quality as compared to fat-tail in south-khorasan. the natural pastures also may alter the fatty acid composition of meat and fat-tail's sheep.