El Azzi MS, Valdes-Arciniega T, Anta-Galvan E, Leão IM, Sala RV, Fosado M, de Souza JC, Martins JPN. Effects of human chorionic gonadotropin on the last day of a 5-day CIDR Synch protocol and 5 days later on circulating progesterone concentrations and luteal area in Holstein heifers.
JDS COMMUNICATIONS 2022;
3:368-372. [PMID:
36340909 PMCID:
PMC9623746 DOI:
10.3168/jdsc.2022-0220]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/16/2022] [Indexed: 11/19/2022]
Abstract
The hCG on the last day of a 5-day CIDR Synch (day 0) enhanced original CL area on day 5.
The hCG versus GnRH on day 0 increased serum P4 on day 5, 7, and 12.
The hCG on day 5 induced accessory CL formation and increased serum P4 on day 7 and 12.
The hCG on day 5 augmented original CL area on day 12 compared with no hCG on day 5.
The hCG on day 0 and 5 (HH) increased serum P4 on day 7 compared with the other treatments.
The objective was to determine the effect of replacing GnRH with human chorionic gonadotropin (hCG) on the last day of a 5-d CIDR Synch protocol (d 0) and inducing accessory corpus luteum (CL) formation with hCG 5 d later (d 5) on serum progesterone (P4) concentrations and luteal dynamics in dairy heifers. Holstein heifers (n = 207) were synchronized with a 5-d controlled internal drug release (CIDR) Synch protocol (d −8: used CIDR inserted; d −3: CIDR removed and PGF2α). Heifers were randomly assigned to 1 of 4 treatments on d 0: control (G; n = 55), H (n = 50), GH (n = 53), and HH (n = 49). Heifers in G were treated with 100 μg of GnRH on d 0, while H heifers received hCG (3,300 IU) on d 0. Heifers enrolled in GH were treated with GnRH on d 0 and hCG on d 5, while HH received hCG on d 0 and 5. Ovaries were scanned by ultrasound on d 0, 5, and 12, and blood was collected on d 0, 5, 7, and 12. Heifers that ovulated before or after the hCG or GnRH d 0 treatment and had P4 ≤ 0.50 ng/mL on d 0 were considered as synchronized. Overall protocol synchronization response was 93.8%, with no differences among treatments. Only synchronized heifers (n = 193) were included in the analyses of luteal dynamics after d 0. Serum P4 concentration and original CL luteal area on d 5 in heifers treated with hCG on d 0 (H + HH) were greater than in heifers treated with GnRH on d 0 (G + GH). Almost all heifers treated with hCG on d 5 had ≥2 CL on d 12 (98.6%). Ovulatory response for d 5 hCG treatment did not differ for GH versus HH (97.2 vs. 94.7%). Heifers in HH had the highest serum P4 on d 7, and G had the lowest serum P4 on d 7 and 12. In contrast, serum P4 on d 7 did not differ for H versus GH. On d 12, serum P4 and total luteal area were not different for GH versus HH. In summary, heifers that received hCG on d 0 had a larger total luteal area and greater serum P4 concentration on d 5 than heifers treated with GnRH on d 0. Moreover, hCG on d 5 promoted a greater proportion of heifers with ≥2 CL on d 12 and a larger luteal area of the original CL, which resulted in a larger total luteal area on d 12. The HH treatment successfully increased serum P4 concentrations in heifers on d 7 compared with the other treatments.
Collapse