The long-term effect of protein malnutrition on concentrations of growth hormone and insulin-like growth factor-I in female lambs
1999
Gladysz, A. | Polkowska, J. (Polish Academy of Science, Jablonna (Poland). Kielanowski Inst. of Animal Physiology and Nutrition) | Krejci, P. | Simunek, J. | Tomanek, M.
The present study was designed to set up the influence of long-term protein restriction in the diet of growing female lambs on the level of growth hormone (GH) and insulin-like growth factor-I (IGF-I) in blood plasma and to carry out adaptations for the method of estimation of blood plasma IGF-I in the sheep. For the period of 12 weeks lambs were subjected to an isocaloric diet containing either a low (8 %) or a high (18 %) amount of protein. The results obtained by radioimmunoassay showed that the mean concentration of GH was significantly higher in the group fed the low protein diet (8.0+/-3.9 vs. 4.2+/-1.6 ng/ml) and this difference was associated with a significant elevation of the pulse amplitude (8.0+/-4.4 vs 2.7+/-1.4 ng/ml). The level of IGF-I did not differ significantly between the two groups of sheep (56.4+/-3.9 ng/ml vs. 52.2+/-5.3 ng/ml). The results indicate, that long-term restrictions of dietary protein in growing lambs augment the GH secretion but have no effect on the IGF-I levels.
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