The somatotropic axis in neonatal calves can be modulated by
nutrition, growth hormone and long-r3-igf-i.
Hammon, H., and J. W. Bluma.
Division of Nutrition Pathology, Institute of Animal Breeding,
University, Berne, Switzerland
APStracts 4:0057E, 1997.
Effects on the somatotropic axis (plasma levels of insulin-like growth
factors [IGFs] I and II, IGF-binding proteins [IGFBPs] and growth
hormone [GH]) of feeding different amounts of colostrum or milk
replacer, of Long-R3-IGF-I (administered s.c. or orally; 50 [mu]g/kg
body weight/d for 7 d) and of s.c. injected recombinant bovine GH
(rbGH; 1 mg/kg body weight/d for 7 d) were evaluated in calves during
the first wk of life. Plasma Long-R3-IGF-I increased after s.c.
application, but not with the oral dose. Endogenous IGF-I was higher
in calves fed colostrum six times compared to those fed only milk
replacer. Native IGF-I was highest in rbGH injected calves, but was
lowered by the s.c. injection of Long-R3-IGF-I. IGF concentrations
were not modified by any of the treatments. IGFBP-2 increased in
calves fed only milk replacer and those receiving s.c. Long-R3-IGF-I.
GH was not modulated by differences in nutrition, but increased after
rbGH administration and similarly in all groups after i. v. injection
of GH releasing factor analog GRF-(1-29). Parenteral administration
of Long-R3-IGF-I decreased GH concentration, but did not affect the
secretory pattern. The data demonstrate that the somatotrophic axis
is basically functioning in neonatal calves and is influenced by
nutrition, GH and Long-R3-IGF-I.
Received 2 July 1996; accepted in final form 17 February 1997.
APS Manuscript Number E311-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 12 March 1997