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The effect of the α2-adrenergic agonist, guanfacin, on the energy metabolism of steers fed on low-quality-roughage diets

Published online by Cambridge University Press:  09 March 2007

R. A. Hunter
R. A. Hunter
Affiliation:
CSIRO Division of Tropical Animal Production, PO Box 5545, Rockhampton Mail Centre, Queensland 4702, Australia
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Abstract

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The effect of the α2-adrenergic agonist, guanfacin, on the energy metabolism, feed intake and live weight (LW) change of steers was studied in three experiments. In the first, the metabolic rate of twelve steers was measured after a 72 h fast. The next day, after a 96 h fast, six steers were injected intramuscularly with 15 mg guanfacin in sterile saline (9 g sodium chloride/l) and six with sterile saline alone, and metabolic rate was measured again. Treatment significantly (P < 0.01) lowered metabolic rate by approximately 20% (53.9 v. 66.8 kJ/kg per d). In the second experiment twelve steers were fed on long-chopped, low-quality roughage (Pangola grass (Digitaria decumbens) hay) ad lib. for 6 weeks. Six steers were continuously infused through a jugular catheter with 15 mg guanfacin/d (about 40 μg/kg LW) in sterile saline. The other six served as controls. There was no significant effect of treatment on feed intake (g dry matter (DM)/kg LW) or the rate of LW loss. Treatment significantly (P < 0.05) increased the retention time of fluid (17.9 v. 22.1 h) in the alimentary tract. In the final experiment twenty-three steers were divided into four treatment groups and fed on long-chopped, low-quality roughage (Pangola hay). Treated animals were continuously infused with guanfacin at the rate of 20, 40 or 80 μg/kg LW per d. Control steers were not infused. At the end of the 6-week feeding period metabolic rate was measured after a 72 h fast. Regardless of dose, guanfacin significantly (P < 0.01) lowered metabolic rate. Feed intake was not significantly affected by treatment but the rate of LW loss was significantly (P < 0.05) less in treated steers.

Keywords

Guanfacinα2-Adrenergic agonistEnergy metabolismLow-quality-roughage dietsSteers
Type
Energy Metabolism
Information
British Journal of Nutrition , Volume 67 , Issue 3 , May 1992 , pp. 337 - 343
Copyright
Copyright © The Nutrition Society 1992

References

REFERENCES

Brown, M. J. & Struthers, A. D. (1985) Guanfacine lowers plasma noradrenalin by peripheral α2-adrenoreceptor stimulation in man. British Journal of Clinical Pharmacology 19, 534P–535P.Google Scholar
Grovum, W. L. & Williams, V. J. (1973) Rate of passage of digesta in sheep 4. Passage of marker through the alimentary tract and the biological relevance of rate-constants derived from the changes in concentration of marker in faeces. British Journal of Nutrition 30, 313–329.CrossRefGoogle ScholarPubMed
Hunter, R. A. & Siebert, B. D. (1986) The effects of genotype, age, pregnancy, lactation and rumen characteristics on voluntary intake of roughage diets by cattle. Australian Journal of Agricultural Research 37, 549–560.CrossRefGoogle Scholar
Hunter, R. A. & Vercoe, J. E. (1987) Reduction of energy requirements of steers fed on low-quality roughage diets using trenbolone acetate. British Journal of Nutrition 58, 477–483.CrossRefGoogle ScholarPubMed
Lindsay, D. B. & Oddy, V. H. (1986). Integration of nutrient intake, nutrient utilization and physiological state. Proceedings of the XIII International Congress of Nutrition, pp. 433–436 [Taylor, T.G. and Jenkins, N. K., editors]. London: John Libbey.Google Scholar
MacRae, J. C., Skene, P. A., Connel, A., Buchan, V. & Lobley, G. E. (1988) The action of the β-agonist clenbuterol on protein and energy metabolism in fattening wether lambs. British Journal of Nutrition 59, 457–465.CrossRefGoogle ScholarPubMed
Oddy, V. H., Gooden, J. M., Hough, G. M., Teleni, E. & Annison, E. F. (1985) Partitioning of nutrients in Merino ewes. II. Glucose utilization by skeletal muscle, the pregnant uterus and the lactating mammary gland in relation to whole body glucose utilization. Australian Journal of Biological Science 38, 95–108.CrossRefGoogle ScholarPubMed
Pacha, W., Salzmann, R. & Scholtysik, G. (1975) Inhibitory effects of clonidine and BS100–141 on responses to sympathetic nerve stimulation in cats and rabbits. British Journal of Pharmacology 53, 513–516.CrossRefGoogle Scholar
Scholtysik, G. (1974). Inhibition of effects of accelerator nerves stimulation in cats and rabbits by BS100–141 and guanabenz. Archives of Pharmacology 282, Suppl., R86.Google Scholar
Scholtysik, G. & Fetkovska, N. (1987) Pharmacology of guanfacine. Cor Vasa 29, 11–16.Google ScholarPubMed
Scholtysik, G., Jerie, P. & Picard, C. W. (1980). Guanfacine. In Pharmacology of Antihypertensive Drugs, pp. 79–98 [Scriabine, A., editor]. New York: Raven Press.Google Scholar
Shiota, M. & Masumi, S. (1988) Effect of norepinephrine on consumption of oxygen in perfused skeletal muscle from cold-exposed rats. American Journal of Physiology 254, E482–E489.Google ScholarPubMed
Smith, T. D. & Leslie, F. M. (1988). Pharmacological characterization of [3H] guanfacine binding. Society for Neuroscience Abstracts 4, 412.Google Scholar
Sorkin, E. M. & Heel, R. C. (1986) Guanfacine: a review of its pharmacodynamic and pharmacokinetic properties, and its therapeutic efficacy in the treatment of hypertension. Drugs 31, 301–336.CrossRefGoogle ScholarPubMed
Thompson, D. A., Penicaud, L. & Welle, S. L. (1984). α2-Adrenoreceptor stimulation inhibits thermogenesis and food intake during glucoprivation in humans. American Journal of Physiology 247, R560-R566.Google Scholar
Weston, R. H. (1979). Feed intake regulation in the sheep. In Physiological and Environmental Limits to Wool Growth, pp. 163–177 [Black, J.L. and Reis, P. J., editors]. Armidale, Australia: University of New England Publishing Unit.Google Scholar
Weston, R. H. & Hogan, J. P. (1967) The digestion of chopped and ground roughages by sheep. 1. The movement of digesta through the stomach. Australian Journal of Agricultural Research 18, 789–801.CrossRefGoogle Scholar