Absorbable deslorelin implants (Ovuplant ®) prolong postpartum anestrus in early ovulating dairy cows

• Published in: Theriogenology 2003-10, Vol.60 (7), p.1227-1238
• Main Authors: Padula, A.M, McGowan, M.R, Macmillan, K.L
• Format: Article
• Language: English
• Subjects: Absorption; Administration, Intravaginal; agonists; Anestrus; animal health; Animals; blood; blood sampling; Cattle - physiology; controlled internal drug release devices; Dairy cow; dairy cows; Drug Implants; estrus; Estrus Synchronization; Female; GnRH agonist; gonadotropin-releasing hormone; Holstein; Lactation; milk composition; milk yield; ovulation; Ovulation - drug effects; Ovuplant; parturition; Postpartum; postpartum interval; Postpartum Period; progesterone; Progesterone - administration & dosage; Progesterone - blood; Time Factors; Triptorelin Pamoate - administration & dosage; Triptorelin Pamoate - analogs & derivatives
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/S0093-691X(03)00143-2

Two experiments were conducted to investigate the use of a bioabsorbable implant of the GnRH agonist deslorelin to temporarily delay the resumption of postpartum ovulatory cycles in Holstein cows. In Experiment 1, recently calved cows were paired and received either a single implant (Ovuplant ®; Peptech Animal Health, Sydney, NSW, Australia) within 48 h of parturition (OVP; n=17), or remained as untreated controls (CON; n=17). Blood samples were collected for plasma progesterone assay three times weekly for 6 weeks to profile the pattern of resumption of ovulatory cycles. In Experiment 2, there were 15 CON and 15 OVP cows initially treated as for Experiment 1 as well as 15 OVP+SYNCH cows. Each cow in the CON and OVP+SYNCH groups received a progesterone vaginal insert (CIDR ®; Genetics Australia, Bacchus Marsh, Vic., Australia) for 7 days at 23 days postpartum (23 dpp) to synchronise estrus in cycling animals or to induce an ovulation with estrus in anestrus animals. Blood samples were collected weekly until removal of the CIDR insert, and then twice weekly until 56 dpp to monitor plasma P4 for retrospective determination of ovulation. Milk yield was monitored by twice daily electronic volume measurements and milk composition with once weekly milk composition analysis. In Experiment 1, CON cows began ovulating from 9 dpp; 15 of 17 had ovulated by the end of blood sampling at 42 dpp. None of the OVP cows ovulated until at least 24 dpp, and only 6 of 17 had ovulated by 42 dpp. The average day of first ovulation was extended from 22.4±2.7 dpp to 39.3±2.7 dpp ( P