PORCINE SOMATOTROPIN, DIETARY-PROTEIN AND ENERGY EFFECTS ON ARGINASE AND TRANSAMINASE ACTIVITIES IN PIGS

Two experiments were conducted with cross-bred barrows to determine th e effect of somatotropin administration on liver enzyme activities. lp l the first experiment, pigs growing from 26 to 55 kg body weight were given two doses of pituitary porcine somatotropin (pST; 0 and 100 mu g per kg body weight) and three levels of dietary energy (60, 80 and 1 00% of free choice intake). In the second experiment, pigs growing fro m 30 to 60 kg body weight were given two doses of recombinant porcine somatotropin (rpST; 0 and 100 mu g per kg body weight) and five levels of dietary crude protein (110, 150, 190, 230 and 270 g crude protein/ kg diet). Liver arginase (ARG, EC 3.5.3.1) and aspartate aminotransfer ase (AAT, EC 2.6.1.1) activities were then determined in organ samples taken at slaughter rime. Dietary energy did not change liver ARG. Act ivities of both ARG and AAT increased as dietary crude protein increas ed. Both pST and rpST decreased ARG, AAT and serum utrea nitrogen. The re was a lack of interaction between rpST therapy and dietary protein on either ARG or AAT activities, suggesting that set nutritional stare s are not required for expression of pST effects.