Comparison of long- versus short-term CIDR-based protocols to synchronize estrus prior to fixed-time AI in postpartum beef cows

This experiment was conducted to compare pregnancy rates in postpartum beef cows resulting from fixed-time AI (FTAI) after treatment with controlled internal drug release (CIDR)-based protocols to synchronize estrus. Cows assigned to the Show-Me-Synch (n=167) protocol received a CIDR from d 0 to 14,...

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Bibliographic Details
Published in:Animal reproduction science 2012-05, Vol.132 (1-2), p.11-16
Main Authors: Nash, J.M, Mallory, D.A, Ellersieck, M.R, Poock, S.E, Smith, M.F, Patterson, D.J
Format: Article
Language:English
Subjects:
Animals
artificial insemination
Beef cow
beef cows
blood sampling
Cattle - physiology
Chi-Square Distribution
controlled internal drug release devices
Controlled internal drug release insert
Dinoprost - administration & dosage
drugs
Estrous synchronization
estrus
Estrus Synchronization - methods
Female
Fixed-time artificial insemination
gonadotropin-releasing hormone
Gonadotropin-Releasing Hormone - administration & dosage
Insemination, Artificial - veterinary
Male
periodicity
Postpartum Period
Pregnancy
pregnancy rate
progesterone
Progesterone - blood
prostaglandins
Random Allocation
sires
technicians
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Summary:This experiment was conducted to compare pregnancy rates in postpartum beef cows resulting from fixed-time AI (FTAI) after treatment with controlled internal drug release (CIDR)-based protocols to synchronize estrus. Cows assigned to the Show-Me-Synch (n=167) protocol received a CIDR from d 0 to 14, and prostaglandin F2α (PGF2α) on d 30. Cows assigned to 7-d CO-Synch+CIDR (n=177) received a CIDR and gonadotropin releasing hormone (GnRH) on d 23. On d 30, CIDRs were removed and PGF2α was administered. Blood sampling occurred on d −10 and 0 of treatment to determine estrous cyclicity status (progesterone ≥0.5ng/mL estrous cycling). Treatments were balanced on age, DPP and BCS. Estrous detection was performed using HeatWatch from PGF2α to FTAI. Artificial insemination was performed at predetermined fixed times (72h, Show-Me-Synch; 66h, 7-d CO-Synch+CIDR) and all cows were administered GnRH at FTAI. This experiment was conducted over a two year period; no differences were found between years so the data were pooled for further analysis. Pregnancy rate resulting from FTAI did not differ (P>0.10) between technicians or AI sires. Pregnancy rate resulting from FTAI was similar between treatments (P=0.20); however, cows that exhibited estrus prior to FTAI had a higher pregnancy rate (P
ISSN:0378-4320
1873-2232
DOI:10.1016/j.anireprosci.2012.03.013