Superovulatory response following transvaginal follicle ablation in cattle.
A study was designed to compare superovulatory responses in cattle when gonadotropin treatment followed 1 of 3 different treatments to synchronize follicular wave emergence. Animals at unknown stages of the estrous cycle were randomly assigned to 3 groups: ablation of the 2 largest follicles per pair of ovaries (n = 21); ablation of all follicles > or = 5 mm (n = 19); or intramuscular administration of 5 mg estradiol-17beta plus 100 mg progesterone (n = 23). All animals were given a CIDR-B intravaginally at the time of the respective treatments. Gonadotropin treatment, initiated 1 d after follicle ablation or 4 d after estradiol plus progesterone treatment, in the respective groups, consisted of 200 mg of pFSH divided in decreasing doses twice daily over 4 d. Cloprostenol (500 microg) was given at 48 and 60 h after the first pFSH treatment; CIDR-B devices were removed at the time of the second cloprostenol treatment. Ovarian ultrasonography was done on the days of CIDR-B insertion, first gonadotropin treatment, and at 36 and 72 h after CIDR-B removal. Cattle were inseminated twice, at 60 and 72 h after the first injection of cloprostenol. Ovarian and ova/embryo data were collected at slaughter 5, 6 or 7 d after insemination. No differences were detected among groups in the number of follicles > or = 8 mm at the time of first insemination (20.4 +/- 1.7 vs 16.6 +/- 2.0 vs 19.9 +/- 2.3; P > 0.05). At slaughter, no differences were detected among groups in the numbers of CL (23.3 +/- 1.9 vs 17.9 +/- 1.9 vs 20.1 +/- 2.6; P < 0.05), unovulated follicles > or = 8 mm (2.2 +/- 0.5 vs 2.1 +/- 0.3 vs 3.7 +/- 0.9; P < 0.05), ova/embryos (11.0 +/- 1.4 vs 12.2 +/- 1.3 vs 8.5 +/- 1.3; P < 0.05), fertilized ova (9.4 +/- 1.3 vs 10.1 +/- 1.2 vs 7.5 +/- 1.1; P < 0.05) or transferable embryos (8.2 +/- 1.2 vs 8.4 +/- 1.3 vs 6.5 +/- 0.9; P < 0.05). Variation in the numbers of CL (P = 0.1) and unovulated follicles > or = 8 mm (P < 0.01) was lower in the ablation groups than in the steroid-treated group. Results suggest that follicle ablation is as effective as estradiol plus progesterone in synchronizing follicular wave emergence for superstimulation in cattle, and that ablation of the 2 largest follicles is as efficacious as ablating all follicles > or = 5 mm.
Baracaldo
M I
MI
Department of Herd Medicine and Theriogenology, WCVM, University of Saskatchewan, Saskatoon, Canada.
Martinez
M F
MF
Adams
G P
GP
Mapletoft
R J
RJ
D000818:Animals; D002417:Cattle / Q000502:physiology*; D003008:Cloprostenol / Q000008:administration & dosage; D004624:Embryo Transfer; D004958:Estradiol / Q000008:administration & dosage; D004971:Estrus; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage; D006080:Ovarian Follicle / Q000033:anatomy & histology / Q000502:physiology* / Q000601:surgery; D011374:Progesterone / Q000008:administration & dosage; D013480:Superovulation; D014463:Ultrasonography
D003008:Cloprostenol; D011374:Progesterone; D004958:Estradiol; D005640:Follicle Stimulating Hormone