Recombinant bovine somatotropin increases nutrient absorption by the proximal small intestine in sheep

Dorset crossbred ewes were used to determine the effect of recombinant methionyl bovine somatotropin (bST) on small intestinal nutrient absorption. Ewes were kept indoors in individual pens and allowed free access to a concentrate diet (18% CP). (150 μg kg−1) or saline were subcutaneously injected once daily for 10 d. An in vitro assay system was used to estimate the rate of accumulation of 3H-3-O-methylglucose and 14C-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 concentrations were significantly higher in ewes treated with bST. In the duodenum, active and total glucose absorption were greater (P < 0.05) in bST treated ewes. There was also a tendency for bST treatment to increase duodenal total proline absorption (P < 0.10). Glucose and proline absorption in the jejunum and ileum were not significantly affected by bST. Jejunal ouabain-sensitive and ouabain-insensitive oxygen consumption was similar in ewes administered saline or bST. Water, DNA and protein content of small intestinal mucosa were unaffected by bST administration. These results indicate that bST upregulates glucose transport in the duodenum of sheep. Key words: Intestine, nutrient absorption, somatotropin, IGF-I, sheep