51 Comparison of SexedULTRA 4M and conventional semen for in vitro production of bovine embryos using two bulls

Abstract

SexedULTRA 4M™ (Select Sires) is made using an improved method of sex-sorting sperm in a less damaging environment for retaining sperm integrity through the sorting process. The combination of in vitro embryo production (IVP) and sexed semen technologies has been successful for intensity selection in the cattle industry. The objective of this research was to compare conventional (CONV) and SexedULTRA 4M (ULTRA-4M) semen for bovine IVP using 2 bulls. The research was carried out in the reproduction laboratory at Palominos Ranch (Jalisco, México). The IVP was performed with a continuous in vitro culture system. Ovaries from commercial cattle (n = 213) were collected from a slaughterhouse (León, 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 sulphate (100 µg mL⁻¹). For IVP, IVF Bioscience™ media were used for IVM, IVF, and in vitro culture (IVC). For the IVM, the cumulus–oocyte complexes (COCs) were selected (grades 1 and 2) and matured for 24 h at 38.5°C in 5% CO₂ in air and 100% humidity. Matured oocytes (n = 1200, divided equally into 3 replicates) were divided into 2 groups, the CONV group and the ULTRA-4M group. The IVF process was conducted with both CONV and ULTRA-4M semen from the 2 bulls, separately, at an adjusted concentration of 2 × 10⁶ and 0.5 × 10⁶ sperm mL⁻¹, respectively, for 18 h in 38.5°C, 5% CO₂ in air, and 100% humidity. The presumptive zygotes were denuded by pipetting and set in IVC until Day 7 at 38.5°C, 5% CO₂, 5% O₂ and 90% N₂ at 100% humidity. The cleavage rate, embryos with more than 6 cells, and blastocysts on Day 7 of culture were evaluated. Statistical analysis was carried out with the GLM procedure of SAS (version 9.3; SAS Institute Inc.) to evaluate the results of CONV versus ULTRA-4M for each bull (α level = 0.05). Cleavage rates were 57.1% ± 1.5 and 59.4% ± 1.5, respectively in CONV and ULTRA-4M groups with Bull 1 and 43.3% ± 1.5 and 45.2% ± 1.5 with Bull 2. The percentages of embryos with more than 6 cells were 51.4% ± 1.0 and 53.9% ± 1.0, respectively, with CONV and ULTRA-4M with Bull 1 and 30.4% ± 1.0 and 33.4% ± 1.0 with Bull 2. The percentage of blastocysts on Day 7 with Bull 1 was 34.4% ± 1.7 for CONV and 36.2% ± 1.7 for ULTRA-4M; for Bull 2, the results were 26.5% ± 1.7 for CONV and 29.5% ± 1.7 for ULTRA-4M. There were no significant differences between the CONV and ULTRA-4M groups (P > 0.05) for all variables analysed for each bull; however, Bull 1 was significantly superior to Bull 2 for all variables analysed. In conclusion, under the conditions of this research, ULTRA-4M and CONV semen produced similar bovine IVP results.