Superstimulation of ovarian follicular growth with FSH oocyte recovery, and embryo production from Zebu (Bos indicus) calves: effects of treatment with a GnRH agonist or antagonist.
The capacity of heifer calves of a late sexually maturing Zebu (Bos indicus) genotype to respond to superstimulation with FSH at a young age and in vitro oocyte development were examined. Some calves were treated with a GnRH agonist (deslorelin) or antagonist (cetrorelix) to determine whether altering plasma concentrations of LH would influence follicular responses to FSH and oocyte developmental competency. Brahman calves (3-mo-old; 140 +/- 3 kg) were randomly assigned to 3 groups: control (n = 10); deslorelin treatment from Day -8 to 3 (n = 10); and cetrorelix treatment from Day -3 to 2 (n = 10). All calves were stimulated with FSH from Day 0 to 2, and were ovariectomized on Day 3 to determine follicular responses to FSH and to recover oocytes for in vitro procedures. Before treatment with FSH, heifers receiving deslorelin had greater (P < 0.001) plasma LH (0.30 +/- 0.01 ng/ml) than control heifers (0.17 +/- 0.02 ng/ml), while plasma LH was reduced (P < 0.05) in heifers treated with cetrorelix (0.13 +/- 0.01 ng/ml). Control heifers had a surge release of LH during treatment with FSH, but this did not occur in heifers treated with deslorelin or cetrorelix. All heifers had large numbers of follicles > or = 2 mm (approximately 60 follicles) after superstimulation with FSH, and there were no differences (P > 0.10) between groups. Total numbers of oocytes recovered and cultured also did not differ (P > 0.05) for control heifers and heifers treated with deslorelin or cetrorelix. Fertilization and cleavage rates were similar for the 3 groups, and developmental rates to blastocysts were also similar. Zebu heifers respond well to superstimulation with FSH at a young age, and their oocytes are developmentally competent.
Maclellan
L J
LJ
Animal Sciences and Production Group, Central Queensland University, Rockhampton, Australia.
Whyte
T R
TR
Murray
A
A
Fitzpatrick
L A
LA
Earl
C R
CR
Aspden
W J
WJ
Kinder
J E
JE
Grotjan
H E
HE
Walsh
J
J
Trigg
T E
TE
D'Occhio
M J
MJ
D000818:Animals; D002417:Cattle / Q000196:embryology* / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D005307:Fertilization in Vitro / Q000662:veterinary*; D005640:Follicle Stimulating Hormone / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000819:agonists / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology*; D016014:Linear Models; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism; D008297:Male; D009865:Oocytes / Q000502:physiology; D006080:Ovarian Follicle / Q000187:drug effects / Q000502:physiology*; D010052:Ovariectomy / Q000662:veterinary; D011374:Progesterone / Q000097:blood; D011863:Radioimmunoassay / Q000662:veterinary; D011897:Random Allocation; D013480:Superovulation / Q000502:physiology; D017329:Triptorelin Pamoate / Q000031:analogs & derivatives
D004791:Enzyme Inhibitors; D006727:Hormone Antagonists; D017329:Triptorelin Pamoate; D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; C062876:cetrorelix; C066438:deslorelin