beef heifers, puberty, gnrh, progesterone, lh
A study using twelve prepuberal Angus heifers was conducted to determine the effects that synthetic progesterone with or without gonadotropin-releasing hormone (GnRH) had on blood serum concentrations of progesterone, estradiol, and luteinizing hormone (LH) over a 48-hour period. Four heifers were given an implant containing the synthetic progestogen norgestomet for 9 days. Four other heifers were given a similar implant and also received an injection of GnRH after implant removal. The remaining four heifers served as controls and received no treatment. Serum progesterone and estradiol concentrations did not differ between treatments (P> .8). Heifers receiving norgestomet and GnRH had increased levels of serum luteinizing hormone (LH) during the 4.5 hours following the injection (P< .0001). Serum LH concentrations in heifers treated with norgestomet only did not differ from those of controls.
Number of Pages
South Dakota State University
Copyright © 1994 South Dakota State University.
Henderson, C. L.; Miller, H. L.; Long, M. B.; and Marshall, D. M., "Effects of Progesterone or Progesterone and GnRH Administration on Blood Serum Progesterone, Estradiol and Luteinizing Hormone in Prepuberal Beef Heifers" (1994). South Dakota Beef Report, 1994. 13.