Abstract
The differences of intramuscular lipid compositions in Large White (W), Berkshire (B) and Duroc (D) breeds fattened up to 90kg were studied. The Intramuscular lipids were extracted from M. longissimus thoracis, M. biceps femoris and M. semimembranosus which taken from three barrows and three gilts of each three breeds above and were separated by high-performance thin-layer chromatography. The standard lipids which used for drawing up the calibration curves were developed on the same thin-layer plates simultaneously with intramuscular lipids. The lipid spots were visualized with 25% percloric acid and the areas of lipid spots were scaned with the Model CS-9000 dual wavelength flaying spot scanner (Shimadzu Co.). The lipid compositions were indicated by weight percentage.
The following results were obtained.
1) The detectable components in intramuscular lipid in present experiment were triacylglycerol (TG), free fatty acid (FFA), cholesterol (CH), phosphatidyl ethanolamine (PE), phosphatidyl choline (PC), sphingomyeline (SPM) and lysophosphatidyl choline (LPC).
2)The intramuscular lipids were composed of approx. 63-85% of TG, 10-23% of PC, 2.3-6.0% of PE, 1.3-3.3% of CH, 0.7-1.7% of SPM, 0.5-1.7% of FFA and 0.05-0.44% of SPM depending upon the type of muscle and breed.
3) The neutral lipid fraction (NL) was high in TG and in proportion from 92% to 98%. In the phospholipid fraction (FL), the predominant component was the PC followed by PE, both comprising from 92% to 94% of the PL.
4) Duroc breed, as compared with Large White and Berkshire, contained significantly higher NL and TG but less other components of lipids. In Large White and Berkshire, there were no remarkable differences in the composition of intramuscular lipids in M. biceps femoris and M. semimembranosus, but the proportion of TG in M. longissimus thoracis of Large White was significantly lower and the proportions of other components were relatively higher than those in Berkshire.
5) It was shown that the effects of breeds on the proportion of each component of PL to total PL were comparatively small.
On the basis of the findings mentioned above, it was suggested that the differences in the intramuscular lipid compositions among the different breeds depended on the fat deposited in muscles. It was also suggested that the differences among breeds in the proportion of the each component of PL were comparatively small.
