123 Pregnancy rates using cryopreserved in vitro sexed embryos derived from Holstein prepubertal calf and cow oocytes
H. Álvarez-Gallardo A , A. Velázquez-Roque B , J. Martínez-Sandoval C , E. Ochoa-Estrada C , L. Arenas-Sánchez C , M. Kjelland D E , F. Villaseñor-González F and S. Romo GA Centro Nacional de Recursos Genéticos, INIFAP, Tepatitlán, Jalisco, México
B Private practice, H&A Biotecnologías en Reproducción Animal, Tepatitlán, Jalisco, México
C Private Practice, Rancho la Estancia, La Estancia, Querétaro, México
D Conservation, Genetics & Biotech, LLC, Valley City, North Dakota, USA
E Mayville State University, Mayville, North Dakota, USA
F Campo Experimental Centro Altos de Jalisco, INIFAP, Tepatitlán, Jalisco, México
G Facultad de Estudios Superiores Cuautitlán, UNAM, Cuautitlán, Estado de México, México
Reproduction, Fertility and Development 35(2) 188-189 https://doi.org/10.1071/RDv35n2Ab123
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
At present, in vitro embryo production (IVP) and embryo transfer (ET) have had a great impact on animal production. IVP is a very useful tool for genetic improvement in cattle. IVP using prepubertal females reduces the generation interval and significantly improves the rate of genetic gain associated with the use of sexed semen and increases the intensity of selection. The objective of this research was to compare the pregnancy rates of heifers using cryopreserved IVP embryos (at the same farm) derived from prepubertal calf oocytes (PCO) and cow oocytes (CO) after ET. PCO were collected by laparoscopic ovum pickup (LOPU) from five Holstein calves (3 months) synchronised with an intravaginal device (IVD) CIDR-G (0.3 g) on Day 0. On Day 2, FSH (120 mg total) was administered IM every 8 h in five applications; 8 h after the fifth application, 400 IU of equine chorionic gonadotrophin (eCG) was applied. On Day 5, the CIDRs-G were removed and LOPU was performed. CO were collected by ovum pickup (OPU) from 10 Holstein cows (3 years old) synchronised with a CIDR (1.9 g) plus 2 mg oestradiol benzoate. On Day 4, FSH (200 mg total) was applied every 12 h in four applications; on Day 7, CIDRs were removed and OPU was performed. Oocytes from both groups were pooled and fertilised with sexed semen from a proven bull for IVP. The presumptive zygotes were cultured (Vitrogen™ IVC medium) for 7 days at 38.5°C, 5% CO2, 5% O2, and 90% N2 at 100% humidity for both groups. On Day 7, the expanded blastocysts from both groups were subjected to a controlled-rate freezing curve after equilibration for 8 to 10 min in freezing medium with EG (Ethylene Glycol Freeze Plus Vigro™) starting in −6°C (seeding) and decreasing 0.5°C min−1 and ending at −32°C, then plunging directly into liquid nitrogen. For the ET, 87 heifers with a body score condition of 2.5 (on a scale from 1–5) were used as recipients and synchronised with a IVD Crestar (1.3 g) plus 250 μg of gonadorelin on Day 0. On Day 7, Crestar was removed and a 500 μg dose of sodic cloprostenol was administered; on Day 9, a dose of 250 μg of gonadorelin was applied; and on Day 16, ET was conducted. Pregnancy rates were evaluated by colour doppler ultrasonography on Day 25 and confirmed by ultrasonography on Day 40 (Table 1). Statistical analysis was carried out using the chi-squared procedure on Jamovi software (version 1.2; The Jamovi project). The results were 53.8% and 62.5% for PCO and CO, respectively. There were no significant differences between the groups (P = 0.55). In conclusion, under the conditions of this research, the cryopreserved IVP sexed embryos with PCO and CO produced similar pregnancy rates after ET.
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