Evaluation of prostaglandin F2αversus prostaglandin F2αplus gonadotropin-releasing hormone as Presynch methods preceding an Ovsynch in lactating dairy cows: A meta-analysis.
Presynchronization of cows with 2 injections of prostaglandin administered 14 d apart (Presynch-Ovsynch) is a widely adopted procedure to increase pregnancy per artificial insemination (P/AI) at first service. Recently, a presynchronization protocol including GnRH and PGF2α(Double-Ovsynch; GnRH, 7 d, PGF2α, 3 d, GnRH) followed 7 d later by an Ovsynch protocol was introduced to overcome the limitations of PGF2α-based protocols for presynchronization of anovular cows and to precisely set up cows on d 7 of the estrous cycle when the Ovsynch is initiated. A systematic review of the literature and a meta-analytical assessment was performed with the objective to compare the reproductive performance of lactating dairy cows presynchronized with these 2 protocols for the first timed AI (TAI) considering parity-specific effects. A fixed or a random effects meta-analysis was used based on the heterogeneity among the experimental groups. Reproductive outcomes of interest were P/AI measured on d 32 (28-42) and pregnancy loss between d 32 and 60 (42-74) of gestation. A total of 25 articles with 27 experimental groups from 63 herds including 21,046 cows submitted to first TAI using either a Presynch-Ovsynch or a Double-Ovsynch protocol were reviewed. Results for P/AI were then categorized by parity if available. Information was available for P/AI for 7,400 and 10,999 primiparous and multiparous cows, respectively. Information regarding pregnancy loss was available for 7,477 cows. In the random effects model for all cows, the overall proportion of P/AI was 41.7% [95% confidence interval (CI): 39.1-44.3; n = 8,213] and 46.2% (95% CI: 41.9-50.5; n = 12,833) on d 32 after TAI for Presynch-Ovsynch and Double-Ovsynch, respectively. In the random effects model for primiparous cows, the overall proportion of P/AI was 43.4% (95% CI: 36.2-47.7; n = 2,614) and 51.4% (95% CI: 47.4-55.4; n = 4,786) on d 32 after TAI for Presynch-Ovsynch and Double-Ovsynch, respectively. In the random effects model for multiparous cows, the overall proportion of P/AI was 39.2% (95% CI: 36.2-42.3; n = 3,411) and 41.4% (95% CI: 36.4-46.4; n = 7,588) on d 32 after TAI for Presynch-Ovsynch and Double-Ovsynch, respectively. The overall proportion of pregnancy loss was 11.3% (95% CI: 7.6-15.7; n = 3,247) and 11.7% (95% CI: 9.3-14.3; n = 4,230) on d 60 after AI for Presynch-Ovsynch to and Double-Ovsynch, respectively. Substantial heterogeneity existed among the experimental groups regarding P/AI and pregnancy loss. In summary, a benefit was detected for P/AI in primiparous cows presynchronized with a Double-Ovsynch protocol for the first TAI, but this benefit was not observed in multiparous cows.
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
S
S
Borchardt
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
P
P
Haimerl
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
A
A
Pohl
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany. Electronic address: w.heuwieser@fu-berlin.de.
W
W
Heuwieser
D000034:Abortion, Veterinary; D000818:Animals; D002417:Cattle; D015237:Dinoprost / Q000008:administration & dosage*; D004973:Estrus Synchronization; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage*; D007315:Insemination, Artificial / Q000662:veterinary; D007774:Lactation; D011374:Progesterone
D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D015237:Dinoprost
Double-Ovsynch; Presynch-Ovsynch; meta-analysis; presynchronization