RECOMBINANT BOVINE SOMATOTROPIN INCREASES NUTRIENT ABSORPTION BY THE PROXIMAL SMALL-INTESTINE IN SHEEP

Sixteen Dorset crossbred ewes were used to determine the effect of rec ombinant methionyl bovine somatotropin (bST) on small intestinal nutri ent absorption. Ewes were kept indoors in individual pens and allowed free access to a concentrate diet (18% CP). bST (150 mu g kg(-1)) or s aline were subcutaneously injected once daily for 10 d. An in vitro as say system was used to estimate the rate of accumulation of H-3-3-O-me thylglucose and C-14-proline by small intestinal segments. Feed intake and liveweight gain were similar in ewes administered bST or saline. At the end of the treatment period, plasma ST, IGF-I and glucose conce ntrations were significantly higher in ewes treated with bST. In the d uodenum, active and total glucose absorption were greater (P < 0.05) i n bST treated ewes. There was also a tendency for bST treatment to inc rease duodenal total proline absorption (P < 0.10). Glucose and prolin e absorption in the jejunum and ileum were not significantly affected by bST. Jejunal ouabain-sensitive and ouabain-insensitive oxygen consu mption was similar in ewes administered saline or bST. Water, DNA and protein content of small intestinal mucosa were unaffected by bST admi nistration. These results indicate that bST upregulates glucose transp ort in the duodenum of sheep.