Effect of inducing accessory corpus luteum formation with gonadotropin-releasing hormone or human chorionic gonadotropin on the day of embryo transfer on fertility of recipient dairy heifers and lactating cows

• DOI: 10.3168/jdsc.2022-0286
• Publication Date: 2023-02-02T22:30:13Z
• Authors: Marcelo S. El Azzi; João Luiz Cardoso; Raul A. Landeo; José Henrique F. ...; José C. de Souza; João Paulo N. Mar...
• Keywords: Human chorionic gonadotropin; Equine chorionic gonadotropin; Gonadotropin

The objective was to determine the effect of inducing an accessory corpus luteum (CL) using GnRH or human chorionic gonadotropin (hCG) on day in vitro-produced (IVP) embryo transfer (ET) pregnancy per ET (P/ET) and calving/ET dairy heifers lactating cows. Dairy (11-15 mo age; n = 1,547) cows (n 1,480) detected estrus by tail chalk (d 0) were used as recipients. Before ET, presence a CL evaluated transrectal palpation from d 6 9 estrous cycle. Animals with randomly assigned receive 1 3 treatments immediately before ET: control (no treatment; 1,009), (86 µg GnRH; 1,085) hCG (2,500 IU; 1,069). Embryos implanted uterine horn ipsilateral ovary (fresh IVP embryos, 2,544; vitrified embryos 545; slow-freezing 74). Pregnancy diagnosis performed 37 ± gestation palpation. loss data calving records collected farm management software. Treatment did not affect P/ET, calving/ET, either overall within parity. When formation combined (GnRH + hCG), tended have greater P/ET than controls (67.7 vs. 63.5%, respectively). Yet, similar. Response variables also analyzed type For receiving stage (blastocyst) fresh had (74.5 51.1%, In addition, (67.8 51.2%, However, blastocyst similar among treatments. only 7 (expanded blastocyst) considered, primiparous (59.3 47.1%) (48.6 38.1%) hCG. Moreover, showed decreased compared transferred expanded embryos. summary, effects at inconsistent according different characteristics (e.g., stage) parity Furthermore, treatment improve fertility outcomes for recipient animals