Treatment of Cycling and Noncycling Lactating Dairy Cows with Progesterone During Ovsynch

• Published in: Journal of dairy science 2006-07, Vol.89 (7), p.2567-2578
• Main Authors: Stevenson, J.S, Pursley, J.R, Garverick, H.A, Fricke, P.M, Kesler, D.J, Ottobre, J.S, Wiltbank, M.C
• Format: Article
• Language: English
• Subjects: Abortion, Veterinary - epidemiology; Animal productions; Animals; artificial insemination; Biological and medical sciences; Cattle; controlled internal drug release devices; dairy cows; Dinoprost - administration & dosage; embryonic mortality; Estrous Cycle; estrus synchronization; Female; Food industries; Fundamental and applied biological sciences. Psychology; Gonadotropin-Releasing Hormone - administration & dosage; Graafian follicles; Illinois; Insemination, Artificial - methods; Insemination, Artificial - veterinary; Kansas; Lactation; Michigan; Milk and cheese industries. Ice creams; Missouri; Ohio; Ovarian Follicle - anatomy & histology; Ovulation Induction - veterinary; Pregnancy; Pregnancy Outcome; pregnancy rate; progesterone; Progesterone - administration & dosage; Progesterone - blood; Terrestrial animal productions; Vertebrates; Wisconsin
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(06)72333-5

Our objective was to determine whether progesterone (P4) supplementation during an Ovsynch protocol would enhance fertility in lactating dairy cows. Lactating dairy cows (n = 634) at 6 locations were assigned randomly within lactation number and stage of lactation to receive the Ovsynch protocol [OVS; synchronization of ovulation by injecting GnRH 7 d before and 48 h after PGF₂α, followed by one fixed-time AI (TAI) 16 to 20 h after the second GnRH injection] or Ovsynch plus a controlled internal drug release (CIDR) P4-releasing insert for 7 d, beginning at the first GnRH injection (OVS + CIDR). Blood was sampled to quantify P4 10 d before the first GnRH injection, immediately before the first GnRH injection, at the time of CIDR removal, before the PGF₂α injection (1 to 2 h after CIDR insert removal), and 48 h after the PGF₂α injection to determine cyclicity status before initiation of treatment, luteal status at the PGF₂α injection, and incidence of luteal regression. Overall, conception rates at 28 (40 vs. 50%) and 56 d (33 vs. 38%) after TAI differed between OVS and OVS + CIDR, respectively; but a treatment x location interaction was detected. Compared with OVS, pregnancy outcomes were more positive for OVS + CIDR cows at 4 of 6 locations 28 d after TAI and at 3 of 6 locations 56 d after TAI. An interaction of luteal status (high vs. low) before CIDR insert removal and PGF₂α injection with pretreatment cycling status indicated that cows having low P4 at PGF₂α injection benefited most from P4 supplementation (OVS + CIDR = 36% vs. OVS = 18%), regardless of pretreatment cycling status. Pregnancy loss between 28 and 56 d after TAI was greater for noncycling cows (31%) compared with cycling cows (16%). Pregnancy loss for cows receiving P4 (21%) did not differ from that for cows not receiving P4 (21%). Supplementation of P4, pretreatment cycling status, and luteal status before PGF₂α injection altered follicular diameters at the time of the second GnRH injection, but were unrelated to pregnancy outcomes. Incidence of multiple ovulation was greater in noncycling than in cycling cows. Further, cows having multiple ovulations had improved pregnancy outcomes at 28 and 56 d after TAI. In summary, a CIDR insert during the Ovsynch protocol increased fertility in lactating cows having low serum P4 before PGF₂α injection. Improved pregnancy outcomes were observed at some, but not all locations.