Induced corpora lutea in the postpartum beef cow. II. Effects of treatment with progestogen and gonadotropins.

摘要: Seventy-three multiparous beef cows (21 to 35 d postpartum) were used in an experiment with a 2 X 4 factorial design test the effects of pretreatment norgestomet and preovulatory gonadotropic stimulation on life span corpora lutea induced by human chorionic gonadotropin (hCG). Cows implanted subcutaneously for 9 (3 mg; cows) or sham-implanted (38 cows). HCG (1,000 IU) was administered all 36 h (time = 0) after implant removal. Each cow received one following treatments: (1) pregnant mare's serum (PMSG; 750 single subcutaneous injection 48 prior hCG (-48 h); (2) follicle hormone (FHS-P) saline (10 mg) series four injections (2.5 mg/injection) at -48, -36, -24 -12 h; (3) FSH-P 5% beeswax-sesame oil as 2; (4) saline, 2. Samples taken time implantation, removal daily 5 20 administration assayed progesterone. 12-h intervals from -48 +12 estradiol-17 beta. observed estrus 6-h 24 60 twice until 22. Seventy-one percent (25/35) standing 29 implant, compared 16% (six 38). As determined progesterone palpation ovaries, 88% (64/73) formed response hCG, tendency (P less than equal .10) positive effect (94 vs 82%). The longer .01) treated (19.6 d) (13.4 d). Level function indicated pattern concentrations increased either .05), but there no interaction these treatments. mean level estrogen before ovulation any regimen gonadotropin, and, again, significant interaction. Pretreatment progestogen associated higher concentration over .01).