65 Comparison of SexedULTRA-4M™ X and Y chromosome-bearing semen versus conventional semen for the in vitro production of bovine embryos
A. Velázquez-Roque A , H. Álvarez-Gallardo B C , M. Kjelland D E , M. Pérez-Martínez F , F. Villaseñor-González G and S. Romo BA Private practice, Servicios Integrados Ganaderos, Monterrey, Nuevo León, México
B Facultad de Estudios Superiores Cuautitlán, UNAM, Cuautitlán, México, México
C Centro Nacional de Recursos Genéticos, INIFAP, Tepatitlán, Jalisco, México
D Conservation, Genetics & Biotech LLC, Valley City, ND, USA
E Mayville State University, Mayville, ND, USA
F Facultad de Medicina Veterinaria y Zootecnia, UNAM, CDMX, México
G Campo Experimental Centro Altos de Jalisco, INIFAP, Tepatitlán, Jalisco, México
Reproduction, Fertility and Development 34(2) 268-268 https://doi.org/10.1071/RDv34n2Ab65
Published: 7 December 2021
© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
Sexed semen technology has been modernised and is now known as ULTRA™ (STgenetics). In laboratory trials with in vitro-produced (IVP) bovine embryos, there was no difference between conventional semen (CONV) and X chromosome-bearing SexedULTRA-4M semen (ULTRA-4M) in blastocyst production. However, the scientific literature lacks information about IVP with Y chromosome-bearing ULTRA-4M. The objective of this research was to compare CONV, sexed X chromosome-bearing ULTRA-4M (ULTRA X) and sexed Y chromosome-bearing (ULTRA Y) for bovine IVP. IVP was performed using a continuous in vitro culture system. Ovaries were collected from a slaughterhouse (Léon, México) and transported to the laboratory within 2 h in physiological saline solution (0.9% NaCl) supplemented with penicillin G (100 IU mL−1) and streptomycin sulfate (100 µg mL−1). Vitrogen™ media was used for IVM, IVF, and in vitro culture (IVC). For the IVM (Day −1), cumulus-oocyte complexes (COCs) were selected (only grades 1 and 2), pooled, and matured for 24 h at 38.5°C in 5% CO2, in air and 100% humidity. Matured oocytes (n = 1500) were divided into three groups: CONV, ULTRA X, and ULTRA Y (500 COCs each, in five replicates). The IVF process (Day 0) was performed with CONV and ULTRA-4M semen from the same bull and from sequential ejaculates at concentrations of 2 × 106 and 0.5 × 106 spermatozoa mL−1 respectively, for 18 h in 38.5°C, 5% CO2 in air and 100% humidity. Presumptive zygotes were denuded by pipetting and placed in IVC (Day 1) until Day 7 at 38.5°C, 5% CO2, 5% O2, and 90% N2 at 100% humidity. The cleavage rate (56 h after the beginning of IVC), embryos with more than six cells, and blastocysts on Day 7 of culture (calculated from the initial number of oocytes entering IVM) were evaluated. Statistical analysis was carried out with the ANOVA procedure (α level = 0.05), categorising each kind of semen, using Jamovi software (version 1.2; The Jamovi Project). Cleavage rates were 58.6 ± 6.02, 62.8 ± 7.79, and 49.8 ± 5.36, respectively for CONV, ULTRA X, and ULTRA Y, and the percentages of embryos with more than six cells were 36 ± 6.48, 43.2 ± 6.34, and 26 ± 6.96, respectively. The percentage of blastocysts on Day 7 was 24.6 ± 6.35 for CONV, 29.8 ± 6.65 for ULTRA X, and 9.8 ± 2.59 for ULTRA Y. There were no significant differences in the percent cleavage and embryos with more than six cells between CONV and ULTRA X groups; however, both were significantly higher (P < 0.05) for ULTRA X compared with ULTRA Y. The percentage of blastocysts on Day 7 was significantly higher for ULTRA X compared with CONV and ULTRA Y, and for CONV compared with ULTRA Y. In conclusion, under the conditions of this research, ULTRA X had a higher percentage of blastocysts compared with CONV and ULTRA Y for bovine IVP. Further research may determine if this was due to the second X chromosome of sexed semen-produced XX embryos, which may compensate for DNA damage, but not in the Y sexed semen-produced embryos (XY).
