High demand exists for in vitro-derived bovine embryos fertilized with female sex-sorted sperm by seedstock and commercial cattle producers. The aim of this study was to evaluate different fertilization media on in vitro fertilization performance using female sex-sorted semen. Ovaries were collected from a slaughterhouse and oocytes aspirated from 2- to 6-mm follicles. Cumulus-oocyte complexes containing compact and complete cumulus cell layers were selected and matured in groups of 50 cumulus-oocyte complexes in 400 μL of M199 medium supplemented with ALA-glutamine (0.1 mM), Na pyruvate (0.2 mM), gentamicin (5 μg mL–1), epidermal growth factor (50 ng mL–1), oFSH (50 ng mL–1), bLH (3 μg mL–1), cysteamine (0.1 mM), and 10% fetal bovine serum for 22 to 24 h. Fertilization (Day 0) was carried out using female sex-sorted semen selected with a discontinuous density gradient and diluted to a final concentration of 1 × 106 sperm mL–1. Three different fertilization media, M199 (Gibco 11043–023, Grand Island, NY, USA), SOF (Tervit et al. 1972 J. Reprod. Fertil. 30, 493–497), and TALP (Parrish et al. 1988 Biol. Reprod. 38, 1171–1180), were assayed along with 3 female sex-sorted bulls. All fertilization media were supplemented with fructose (90 μg mL–1), penicillamine (3 μg mL–1), hypotaurine (11 μg mL–1), and heparin (20 μg mL–1). After 18 h, presumptive zygotes were denuded and cultured in groups of 15 to 20 in 50-μL drops of KSOM-BSA for 9 days. On Day 3, 3% fetal bovine serum was added. Low oxygen tension (5% O2) was used for the entire culture period. On Days 7 and 9 blastocysts and hatched embryos, respectively, were morphologically evaluated according to IETS standards and recorded. Results are shown in Table 1. Data was compared by chi-squared analysis. Fertilization media affected cleavage rate and subsequent embryo development, quality, and hatching ability. The SOF and TALP fertilization media produced significantly more and higher quality embryos than M199.
Table 1.In vitro fertilization performance after oocyte fertilization using sex-sorted sperm
Effect of Insulin and Basic Fibroblast Growth Factor (bFGF) on Bovine Embryo Development In Vitro in a Defined Medium after In Vitro Fertilization
