Effects Of Exogenous Porcine Somatotropin Administration On Protein Deposition And Efficiency Of Lysine Utlization In Growing Pigs PDF Download

The overall objective of this dissertation was to examine the developmental effects of the somatotropin/insulin-like growth factor axis on protein and lipid metabolism and how this axis can be modulated by nutrition in growing pigs. The administration of exogenous porcine somatotropin (pST) did not affect growth performance $(P> .10), $ but did increase accretion rates of protein $(P .10)$ were found in circulating IGFBP-3 or IGFBP-2 concentrations. However, circulating concentrations of IGF-I and IGFBP-3 were increased $(P .10)$ in vitro glucose uptake and utilization by adipose tissue explants or the glucose response $(P> .10)$ to an insulin challenge. The nutritional regulation of the IGF system was examined by feeding pigs diets that ranged from low to high protein concentration in relation to their requirements. Protein restriction only minimally reduced $(P = .11)$ circulating IGF-I concentrations and did not affect circulating IGFBP $(P> .10).$ The pST challenge increased $(P .10)$ the IGFBP response to the pST challenge. The results presented here demonstrate that the pST regulation of growth is age-dependent and the age effects appear to be similar between different tissues. Also, only severe protein restriction alters circulating levels of components of the IGF system.