EFFECTS OF EXOGENOUS PORCINE SOMATOTROPIN ON THE DEVELOPMENT OF FAT-CELLS AND FATTY-ACID COMPOSITION IN BACKFAT OF LIVE FINISHING PIGS

The effects of long-term application of recombinant porcine somatotrop in (pST) to Landrace pigs on the development of backfat thickness, fat cells and fatty acid composition were investigated from about the 116 th to the 186th day of life. Biopsy samples from the backfat of 56 cas trates were taken at the beginning of treatment and after 5 and 10 wee ks. The daily injection of 2 or 4 mg of pST induced a considerable dec rease in back growth compared to untreated controls. This was attribut ed to a decreased size (about 18-20%) and number (about 13-25%) of fat cells. The higher dose of 4 mg pST/day induced a greater restriction of fat growth. This was obviously based on differences in fat cell num ber. Furthermore, pST treatment delayed the normal decrease of unsatur ated fatty acids (C 18:2; C 18:3) during the period of growth examined . Therefore, the percentages of unsaturated fatty acids increased, ind icating changes in fat cell metabolism of pST treated pigs.