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

Abstract

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

Regulation of intestinal glucose absorption: A new issue in animal science

“…Similarly bST transgenic mice have intestinal weights and lengths that are greater than wild-type littermates , although glucose transport per milligram of intestinal tissue decreases by as much as 24% (Bird et al 1994c). Recently Bird et al (1996b) reported that duodenal glucose active transport and total proline transport were increased 25-30% in ewes administered recombinant bovine somatotropin for 14 d. No changes were detected in the rate of jejunal or ileal active glucose uptake. Bird et al (1996b) postulated that the site-specific nature of bST on glucose transport in sheep may be indirect via effects on enteroendocrine cells in the proximal gut.…”

“…Recently Bird et al (1996b) reported that duodenal glucose active transport and total proline transport were increased 25-30% in ewes administered recombinant bovine somatotropin for 14 d. No changes were detected in the rate of jejunal or ileal active glucose uptake. Bird et al (1996b) postulated that the site-specific nature of bST on glucose transport in sheep may be indirect via effects on enteroendocrine cells in the proximal gut. Other studies regarding the role of somatotropin on intestinal absorption have been less clear.…”

The effects of short-term recombinant bovine somatotropin treatment on fattening performance, carcass composition and visceral organ weights in karayaka lambs in Turkey

“…Similarly, ovine growth hormone (oGH) and recombinant bovine somatotropin did not alter average daily live weight gain and feed intake (Muir et al 1983;Bird et al 1996). However, McLaughlin et al (1993) found that growth rate was increased and food conversion was improved by somatotropin.…”