Pre-treatment of cattle semen or oocytes with purified milk osteopontin affects in vitro fertilization and embryo development

This study was designed to investigate the effects of pre-incubating cattle spermatozoa or matured oocytes with purified osteopontin (OPN) from cattle milk on fertilization in cattle and embryonic development in vitro. There were two different experiments, semen from six mature Holstein bulls ( Bos Taurus) was frozen with different concentrations of OPN (0, 1, 10, 100 μg/mL). Matured cattle oocytes were also pre-treated with OPN (0, 10, 100 μg/mL). In both experiments, pre-treated oocytes or frozen semen, was processed for in vitro fertilization and embryo development. Significantly more oocytes were fertilized when using frozen semen with 10 μg/mL OPN (bull 2 = 85 ± 4% and bull 5 = 78 ± 4%) than without OPN (bull 2 = 75 ± 4% and bull 5 = 69 ± 4%). Those bulls also had increase in cleavage and embryo development (bull 2 = 85 ± 3%, 41 ± 1.9%; bull 5 = 76 ± 2%, 37 ± 1.8%) compared with control (bull 2 = 75 ± 3%, 30 ± 2%; bull 5 = 68 ± 2%, 29 ± 2%). Incubating matured oocytes in 10 μg/mL OPN (87 ± 3%) and 100 μg/mL OPN (88 ± 3%) significantly increased fertilization than control (73 ± 3%). OPN also improve cleavage, and embryo development in treatments with 10 μg/mL OPN (82.7 ± 1.3%; 31.7 ± 1.4%) and 100 μg/mL OPN (85.8 ± 1.3%; 33.8 ± 1.5%) when compared with control (74.1 ± 1.3%; 24.2 ± 1.2%). These data suggest that both, spermatozoa from some bulls and oocytes may associate with OPN, suggesting a facilitory role on in vitro fertilization and embryo development.