Evaluation of Reproductive Performance in Lactating Dairy Cows with Prostaglandin F2, Gonadotropin-Releasing Hormone, and Timed Artificial Insemination

Abstract

Nine hundred and twenty Holstein cows from 16 commercial dairy herds to evaluate three systematic breeding protocols: 14-d PGF2alpha, timed artificial insemination (AI), and GnRH-PGF2alpha, relative to AI following estrus detection without hormone intervention. The timed AI protocol involved GnRH, followed by PGF2alpha 7 d later and GnRH again 2 d after PGF2alpha, with AI 6 to 18 h after the second GnRH. The GnRH-PGF2alpha protocol consisted of GnRH followed by PGF2alpha 7 d later. Eight herds relied on visual observation to detect estrus, and eight herds utilized the HeatWatch estrus detection system. The average interval to first postpartum AI was shortest for the timed AI protocol (77.1 d) followed by the 14-d PGF2alpha protocol (81.6 d). There was no difference in days to first AI between the control (86.1 d) and GnRH-PGF2alpha (89.5 d) protocols. Percent pregnant per first AI did not differ among control (45.6%), 14-d PGF2alpha (43.7%), or GnRH-PGF2alpha (44.0%) protocols, but all protocols had a higher percent pregnant per first AI than the timed AI protocol (30.1%). Response to the GnRH-PGF2alpha protocol was limited because 44.0% of the cows submitted to the protocol were not detected in estrus < or = 10 d post-PGF2, administration and had an interval to first AI of 103.8 d. Cumulative percent pregnant by 120 d postpartum did not differ between control cows (53.1%) and hormonally treated cows (50.6%). Visual observation herds had a shorter interval to first postpartum AI (82.8 d) than the HeatWatch herds (84.8 d), with a higher overall rate of estrus detection across all protocols (75.3 and 67.6%, respectively).

Comparison of an oestrus synchronisation protocol with oestradiol benzoate and PGF2α and insemination at detected oestrus to a timed insemination protocol (Ovsynch) on reproductive performance of lactating dairy cows

“…In the current study, pregnancy rates either to the first or overall up to the fourth AI for primiparous and multiparous cows were similar. These results were in agreement with previous studies [29,32].…”

The effect of buserelin injection 12 days after insemination on selected reproductive characteristics in cows

“…In spite of the pregnancy rate being slightly higher in GnRH-PGF 2α protocol than that in PGF 2α -PGF 2α group, there was no significant difference between synchronization protocols. In another study, Jobst et al (2000) obtained similar results by synchronizing the animals with the protocols used in this study. In addition, there was no significant difference in P 4 concentrations among the synchronization methods.…”

“…For dairy farming to remain a profitable enterprise, more attention and skill need to be devoted to increasing reproductive efficiency (Jobst et al 2000). Vasconcelos et al (2006) reported that fertility was influenced by many factors including cyclicity, energy balance, heat stress, parity, milk production, diet and diseases.…”

Effects of presynchronization and postinsemination treatments on pregnancy rates to a timed breeding Ovsynch protocol in dairy cows and heifers

“…Some studies have reported that first lactation cows have greater PR than second or greater lactation cows after synchronization following Ovsynch (Stevenson and Phatak 2005), while others have reported greater PR in multiparous cows (Jobst et al 2000). Studies have also reported greater fertility due to presynchronization in multiparous, but not primiparous cows (Cartmill et al 2001); however, the present study did not find this.…”