Effect in sheep of dietary concentrate content on secretion of growth hormone, insulin and insulin-like growth factor-I after feeding

This study was designed to examine the effects of the proportion of concentrate in the diet on the secretion of growth hormone (GH), insulin and insulin-like growth factor-I (IGF-I) secretion and the GH-releasing hormone (GHRH)-induced GH response in adult sheep fed once daily. Dietary treatments we...

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Bibliographic Details
Published in:Animal science journal 2005-02, Vol.76 (1), p.55-63
Main Authors: Hagino, A. (Tohoku Univ., Sendai (Japan)), Inomata, E, Sato, T, Ohtomo, Y, Sasaki, Y, Obara, Y
Format: Article
Language:English
Subjects:
BLOOD PLASMA
concentrate content
CONCENTRATES
Diet
FEEDING
growth hormone (GH)
growth hormone-releasing hormone (GHRH)
Growth hormones
HORMONES
INSULIN
INSULIN-LIKE GROWTH FACTOR
insulin-like growth factor-I (IGF-I)
RADIOIMMUNOASSAY
SHEEP
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Summary:This study was designed to examine the effects of the proportion of concentrate in the diet on the secretion of growth hormone (GH), insulin and insulin-like growth factor-I (IGF-I) secretion and the GH-releasing hormone (GHRH)-induced GH response in adult sheep fed once daily. Dietary treatments were roughage and concentrate at ratios of 100:0 (0% con. centrate diet), 60:40 (40% concentrate diet), and 20:80 (80% concentrate diet) on a dry matter basis. Mean plasma concentrations of GH before daily feeding (10.00 to 4.00 hours) were 11.4 +- 0.4, 10.1 +-0.5 and 7.5+- 0.3 ng/mL on the 0.40 and 80% concentrate diet treatments, respectively. A significant decrease in plasma GH concentration was observed after daily feeding of any of the dietary treatments and these decreased levels were maintained for 8 h (0%), 12 h (40%) and 12 h (80%), respectively (P < 0.05). Plasma IGF-I concentrations were significantly decreased 8-12 h and 4-16 h after the end of feeding compared with the prefeeding level in the 40 and 80% concentrate diet treatments. respectively (P < 0.05). GHRH injection brought an abrupt increase in the plasma GH concentrations, reaching a peak 10 min after each injection, but, after the meal, the peak plasma GH values for animals fed 40% (P < 0.05) and 80% (P < 0.01) concentrate diet were lower than that for roughage fed animals. The concentrate content of a diet affects the anterior pituitary function of sheep resulting in reduced baseline concentrations of GH and prolonged GH reduction after feeding once daily.
ISSN:1344-3941
1740-0929
DOI:10.1111/j.1740-0929.2005.00238.x