Effects of ovariectomy and anabolic steroid implantation on the somatotrophic axis in feedlot heifers

C. R. Bailey, G. C. Duff, S. R. Sanders, S Peder Cuneo, C. P. McMurphy, Sean W Limesand, John A Marchello, David W Schafer, M. L. Rhoads, D. M. Hallford

Research output: Contribution to journalArticle

Abstract

A 2 x 2 factorial experimental design was used to evaluate effects of ovariectomy and implantation (200 mg trenbolone acetate and 28 mg estradiol benzoate; Synovex-Plus) on the performance, serum urea nitrogen, serum insulin like growth factor -1 (IGF-1), and mRNA expression of hepatic IGF-1, growth hormone (GH) receptor and estrogen receptor-α as well as pituitary GH, estrogen receptor-α and GH releasing hormone receptor in feedlot heifers. Thirty-two British x Continental heifers were randomly assigned to either an ovariectomized (OVX) or intact group and then to either a control group or a Synovex-Plus implant group. Heifers were fed a 900 g/kg concentrate steam-flaked maize based diet for 42 d. Liver biopsies were taken before OVX for baseline expression of IGF-1, GH receptor and hepatic estrogen receptor-α, which did not differ between treatment groups. Blood and body weight (BW) were taken on d 0, 28, and 42 and one heifer/pen was slaughtered on d 42 for liver and pituitary tissue samples. Initial and final BW did not differ due to OVX or implant. No gender x treatment interaction was observed for average daily gain (ADG) or final BW. Neither OVX nor implant affected ADG for the final 14 d of the feeding period, but 28 and 42 d ADG were greater in implanted than in control heifers. No 2- or 3-way interactions with day were observed for serum urea nitrogen. Serum urea nitrogen was greater in control heifers than in implanted heifers, but gender had no effect. Both implant and OVX increased serum IGF-1 and a gender x treatment interaction was observed. Neither gender nor implant treatment affected hepatic estrogen receptor-α, hepatic IGF-1, hepatic GH receptor, GH releasing hormone receptor, GH, or pituitary estrogen receptor-α. Data indicate that implanting heifers with Synovex-plus increases serum IGF-1, but the reason for this increase cannot be explained by mRNA expression of key somatotropic genes in the present study.

Original languageEnglish (US)
Pages (from-to)207-216
Number of pages10
JournalSouth African Journal of Animal Sciences
Volume38
Issue number3
StatePublished - 2008

Fingerprint

anabolic steroids
ovariectomy
feedlots
heifers
somatomedins
blood serum
liver
urea nitrogen
average daily gain
somatoliberin
gender
hormone receptors
somatotropin
body weight
trenbolone
benzoates
steam
estradiol
biopsy
concentrates

Keywords

  • Gender
  • mRNA
  • Synovex-plus

ASJC Scopus subject areas

  • Animal Science and Zoology

Cite this

Effects of ovariectomy and anabolic steroid implantation on the somatotrophic axis in feedlot heifers. / Bailey, C. R.; Duff, G. C.; Sanders, S. R.; Cuneo, S Peder; McMurphy, C. P.; Limesand, Sean W; Marchello, John A; Schafer, David W; Rhoads, M. L.; Hallford, D. M.

In: South African Journal of Animal Sciences, Vol. 38, No. 3, 2008, p. 207-216.

Research output: Contribution to journalArticle

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