Premature luteal regression in goats superovulated with PMSG: effect of hCG or GnRH administration during the early luteal phase.
Twenty-two goats were superovulated with PMSG; 84 h after the onset of estrus the goats were treated with saline solution (control group n = 7), hCG (hCG group, n = 7), or GnRH (GnRH group, n = 8). The ovaries of all the goats were laparoscopically examined 3 and 6 d after the onset of estrus. In each case the CL were counted and classified according to their appearance as normal-looking or as regressing. Blood samples for progesterone determination were collected every 12 h from Day 1 to Day 6. Premature luteal regression was considered to have occurred if progesterone concentrations declined to less than 1 ng/mL by Day 6. According to progesterone concentrations, 57.5, 0 and 37.5% of the goats underwent premature luteal regression in the control, hCG and GnRH groups, respectively. Progesterone concentrations were higher in the hCG group than in the other groups on Days 5 and 6 post estrus (P < 0.05). The control group was the only one in which there was a significant (P < 0.05) increase in the number of regressing CL between Day 3 (1.6 +/- 1.4) and Day 6 (7.3 +/- 1.4). It was also the only group in which there was a significant decrease in the number of normal-looking CL between Day 3 (12.6 +/- 2.1) and Day 6 (2.6 +/- 2.1). On Day 6 the animals treated with hCG had significantly more normal-looking CL (12.0 +/- 2.3) than those in the control group (2.6 +/- 2.1). The number of large follicles present on the ovaries on Day 6 post estrus had negative correlations with progesterone concentrations (P = 0.05) and with the number of normal-looking CL (P < 0.05). It is concluded that the administration of hCG 84 h after the onset of estrus prevents premature luteal regression in goats superovulated with PMSG.
Saharrea
A
A
Departamento de Reproducción, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, México D.F., México.
Valencia
J
J
Balcázar
A
A
Mejía
O
O
Cerbón
J L
JL
Caballero
V
V
Zarco
L
L
D000818:Animals; D006063:Chorionic Gonadotropin / Q000008:administration & dosage*; D004971:Estrus; D005260:Female; D006041:Goats / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage*; D006064:Gonadotropins, Equine / Q000008:administration & dosage*; D008183:Luteal Phase / Q000187:drug effects*; D003341:Luteolysis; D011374:Progesterone / Q000097:blood; D013480:Superovulation; D013997:Time Factors
D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone