Resynchronization of ovulation and timed insemination in lactating dairy cows, II: assigning protocols according to stages of the estrous cycle, or presence of ovarian cysts or anestrus.
Pregnancy rates were compared in lactating dairy cows (n = 1083) assigned to protocols for resynchronization of ovulation based on stages of the estrous cycle, or presence of ovarian cysts or anestrus. Cows were detected not pregnant by ultrasonography 30 d after a previous AI (study day 0) and classified as diestrus, metestrus, proestrus, with ovarian cysts or anestrus. Cows in diestrus (January-May) were assigned to either Ovsynch (GnRH day 0, PGF2alpha day 7, GnRH day 9, and timed-AI [TAI] 16 h later; n = 96), or Quicksynch (PGF2alpha day 0, estradiol cypionate [ECP] day 1, AI at detected estrus [AIDE] on day 2, or TAI on day 3; n = 96). Cows in diestrus (June-December) were assigned to either Ovsynch (n = 156) or Modified Quicksynch (PGF2alpha day 0, ECP day 1, AIDE days 2 and 3, and to Ovsynch on day 4 if not detected in estrus; n = 142). Cows in metestrus were assigned either to Ovsynch (n = 68), Heatsynch (GnRH day 0, PGF2alpha day 7, ECP day 8, AIDE day 9, or TAI day 10; n = 62), or GnRH + Ovsynch (GnRH on day 0, followed by Ovsynch on day 8; n = 64). Cows in proestrus, with ovarian cysts, or anestrus were assigned to either Ovsynch (proestrus n = 89, ovarian cysts n = 97, anestrus n = 8) or GnRH + Ovsynch (proestrus n = 87, ovarian cysts n = 109, anestrus n = 9). Pregnancy rate was evaluated 30, 55 and 90 d after resynchronized AI. For cows in diestrus (January-May), pregnancy rates were higher for Ovsynch (35.9, 29.2 and 26.0%) than for Quicksynch (21.7, 16.7 and 15.6%). For cows in diestrus (June-December), pregnancy rates were similar for Ovsynch (34.4, 24.0 and 23.6%) and Modified Quicksynch (27.1, 26.2 and 21.6%). For cows in metestrus, pregnancy rates were higher for GnRH + Ovsynch (33.3, 24.5 and 20.3%) than for Heatsynch (20.3, 12.9 and 9.8%). For cows with ovarian cysts, pregnancy rates were higher for GnRH + Ovsynch (30.3, 26.6 and 22.9%) than for Ovsynch (20.2, 18.5 and 14.7%). Assignment to resynchronization protocols based on the stages of the estrous cycle, or presence of ovarian cysts improved pregnancy rates.
Bartolome
J A
JA
Department of Animal Sciences, University of Florida, 459 Shealy Drive, Gainesville, FL 32611-0910, USA.
Sozzi
A
A
McHale
J
J
Melendez
P
P
Arteche
A C M
AC
Silvestre
F T
FT
Kelbert
D
D
Swift
K
K
Archbald
L F
LF
Thatcher
W W
WW
D000780:Anestrus; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases; D004031:Diestrus; D015237:Dinoprost / Q000008:administration & dosage; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D030762:Estrous Cycle; D004973:Estrus Synchronization; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage; D007315:Insemination, Artificial / Q000379:methods / Q000662:veterinary*; D007774:Lactation; D008686:Metestrus; D010048:Ovarian Cysts / Q000662:veterinary*; D010062:Ovulation Induction / Q000379:methods / Q000662:veterinary*; D011247:Pregnancy; D011359:Proestrus; D012621:Seasons; D013997:Time Factors; D014463:Ultrasonography / Q000662:veterinary
D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; C007630:estradiol 17 beta-cypionate; D015237:Dinoprost