Effect of time interval between prostaglandin F₂α and GnRH treatments on occurrence of short estrous cycles in cyclic dairy heifers and cows [Erratum: 2009 Sept. 1, v. 72, no. 4, p. 590.]

• Published in: Theriogenology 2009-04, Vol.71 (6), p.930-938
• Main Authors: Rantala, M.H, Katila, T, Taponen, J
• Format: Article
• Language: English
• Subjects: application timing; blood plasma; cloprostenol; dairy cows; dexcloprostenol; duration; estrous cycle; estrus; estrus induction; gonadotropin-releasing hormone; heifers; hormone secretion; intramuscular injection; luteolysis; milk; progesterone; synthetic prostaglandins
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2008.10.014

Prostaglandin F₂α (PGF₂α) and GnRH treatments, when administered 24h apart during early diestrus, cause short estrous cycles in some dairy cows and heifers [J. Taponen, M. Kulcsar, T. Katila, L. Katai, G. Huszenicza, H. Rodriguez-Martinez, Short estrous cycles and estrous signs after premature ovulations induced with cloprostenol and gonadotropin-releasing hormone in cyclic dairy cows, Theriogenology 2002; 58, 1291-1302]. We investigated the effect of a time interval between PGF₂α and GnRH administration on the appearance of short cycles. Estrus was induced in heifers with dexcloprostenol. A second luteolysis was induced similarly on day 7 after ovulation, and either 0 (T0) or 24h (T24) later an injection of GnRH (0.1mg of gonadorelin) was administered. We monitored ovarian activity with progesterone analyses from blood plasma samples and with ultrasonography. Fourteen cases (12 in T0 and 2 in T24) were excluded due to either incomplete luteolysis (2 cases) or unresponsiveness to GnRH (10 in T0 and 2 in T24). Short estrous cycles (7 to 8 d) were detected in 11/11 and 8/17 heifers in groups T0 and T24, respectively, with a significant difference in the incidence of short cycles (P