Comparison of fatty acid composition among isolated bovine adipocytes withdifferent sizes

The relationship between the diameter of adipocytes distributed in the same piece of subcutaneous adipose tissue and main fatty acid composition from fattening Holstein steers was investigated. A preliminary experiment was ca rried out to investigate whether the isolation process of adipocytes caused any change in the main fatty acid composition. It was shown that there was little difference in the main fatty acid composition of adipose tissue (X) and that of adipocytes (Y) isolated by this method. The regression equatio n was: Y = 0.97X + 0.47, R-2 = 0.99 (p < 0.01). Adipocytes were isolated fr om Holstein steers at the early and late fattening stages and then separate d into two fractions by using a mesh with a pore size of 50 mu m. In adipoc ytes from Holstein steers at the late fattening stage, the large adipocytes with a mean diameter of 117.5 mu m contained more (p < 0.01) myristoleic a cid (14:1), palmitoleic acid (16:1) and oleic acid (18:1), and less (p < 0. 01) palmitic acid (16:0) and stearic acid (18 :0) than the small adipocytes with a mean diameter of 28.7 mu m. Similar results have been shown in adip ocytes from Holstein steers at the early fattening stages. The isolated adi pocytes from finishing Holstein steers were separated into four fractions b y using meshes with pore size of 25, 50, 75 and 100 mu m. The mean diameter of adipocytes in fractions 1, 2, 3 and 4 were 35.2, 80.5, 113.7 and 141.7 mu m, respectively. With increasing adipocyte size, the rates of myristolei c acid (14:1) and palmitoleic acid (16:1) increased (the correlation coeffi cients were 0.93, p < 0.01 and 0.86, p < 0.01, respectively), whereas that of palmitic acid (16:0) and stearic acid (18:0) decreased (the correlation coefficients were -0.44 and -0.80, p < 0.01, respectively). It is suggested that the size of adipocyte is one of the important determinants of fatty a cid composition in subcutaneous adipocytes of Holstein steers.