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.

Autor:	El Azzi MS; Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison 53706.; Faculdade de Zootecnia e Medicina Veterinária, Universidade Federal de Lavras, Lavras MG 37200-900, Brazil., Cardoso JL; ABS-Global, Kennewick, WA 99338., Landeo RA; Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison 53706., Pontes JHF; ABS-Global, DeForest, WI 53532., de Souza JC; Faculdade de Zootecnia e Medicina Veterinária, Universidade Federal de Lavras, Lavras MG 37200-900, Brazil., Martins JPN; Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison 53706.
Jazyk:	angličtina
Zdroj:	JDS communications [JDS Commun] 2023 Feb 02; Vol. 4 (2), pp. 155-160. Date of Electronic Publication: 2023 Feb 02 (Print Publication: 2023).
DOI:	10.3168/jdsc.2022-0286
Abstrakt:	The objective was to determine the effect of inducing an accessory corpus luteum (CL) using GnRH or human chorionic gonadotropin (hCG) on the day of in vitro-produced (IVP) embryo transfer (ET) on pregnancy per ET (P/ET) and calving/ET in dairy heifers and lactating cows. Dairy heifers (11-15 mo of age; n = 1,547) and lactating cows (n = 1,480) detected in estrus by tail chalk (d 0) were used as recipients. Before ET, the presence of a CL was evaluated by transrectal palpation from d 6 to 9 of the estrous cycle. Animals with a CL were randomly assigned to receive 1 of 3 treatments immediately before ET: control (no treatment; n = 1,009), GnRH (86 µg of GnRH; n = 1,085) and hCG (2,500 IU; n = 1,069). Embryos were implanted in the uterine horn ipsilateral to the ovary with a CL (fresh IVP embryos, n = 2,544; vitrified IVP embryos n = 545; slow-freezing IVP embryos, n = 74). Pregnancy diagnosis was performed on d 37 ± 3 of gestation by transrectal palpation. Pregnancy loss data and calving records were collected from the dairy farm management software. Treatment did not affect P/ET, calving/ET, or pregnancy loss either overall or within parity. When treatments inducing CL formation were combined (GnRH + hCG), heifers tended to have greater P/ET than controls (67.7 vs. 63.5%, respectively). Yet, calving/ET were similar. Response variables were also analyzed within embryo type and parity. For heifers receiving stage 6 (blastocyst) fresh IVP embryos, hCG had greater P/ET than controls (74.5 vs. 51.1%, respectively). In addition, GnRH tended to have greater P/ET than controls (67.8 vs. 51.2%, respectively). However, calving/ET in heifers receiving blastocyst fresh IVP embryos was similar among treatments. When only stage 7 (expanded blastocyst) fresh IVP embryos were considered, primiparous GnRH cows had greater P/ET (59.3 vs. 47.1%) and calving/ET (48.6 vs. 38.1%) than hCG. Moreover, hCG showed decreased calving/ET compared with controls in primiparous cows transferred with expanded blastocyst fresh IVP embryos. In summary, the effects of hCG or GnRH at ET on P/ET and calving/ET were inconsistent according to different embryo characteristics (e.g., embryo stage) and parity of recipients. Furthermore, treatment did not improve the overall fertility outcomes for recipient animals receiving IVP embryos. (© 2023.)
Databáze:	MEDLINE
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