Effect of exogenous progesterone on superovulatory response in heifers inseminated with fresh or frozen semen.
Superovulation in cattle normally involves the administration of gonadotrophins at specific times of the oestrous cycle, followed by the induction of luteolysis and insemination with high quality semen. The first aim of this experiment was to examine the effect of supplementary progesterone when used in conjunction with porcine FSH (pFSH) to induce superovulation in heifers. The methods compared were PGF2 alpha given at mid-cycle or a progesterone-releasing intravaginal device (PRID) inserted at different phases of the cycle. The second aim was to determine whether site of insemination or use of fresh or frozen semen affected embryo production. A factorial design was used involving 185 beef heifers. The main factors were (i) synchronization methods (PGF2 alpha or PRID); (ii) semen type (fresh or frozen); (iii) insemination regimens (involving two inseminations and variations in the sites) and number of straws used (one or two) at the second insemination. Eight injections of pFSH were given twice a day for 4 days starting either on days 9, 10 or 11 of the oestrous cycle or on the fourth day after insertion of a PRID. Heifers were checked for oestrus, inseminated twice and embryos were recovered on day 7 of the superovulated cycle. There was no difference between heifers given either PRID or PGF2 alpha in the oestrous response (93% versus 96%), number of ovulations (15.9 +/- 1.11 versus 13.4 +/- 1.06), large follicles (2.5 +/- 0.24 versus 2.3 +/- 0.23) or embryos recovered (9.1 +/- 0.77 versus 9.1 +/- 0.74).(ABSTRACT TRUNCATED AT 250 WORDS)
Goulding
D
D
National Agricultural and Veterinary Biotechnology Programme, University College Dublin, Belfield, Ireland.
Williams
D H
DH
Roche
J F
JF
Boland
M P
MP
D000818:Animals; D002417:Cattle; D015925:Cryopreservation; D004973:Estrus Synchronization; D005260:Female; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D011374:Progesterone / Q000494:pharmacology*; D012662:Semen Preservation; D013480:Superovulation / Q000187:drug effects*
D011374:Progesterone