95 Effect of Knockout Serum Replacement™ in the culture medium on in vitro bovine embryo production and blastocyst cryotolerance
M. S. Méndez A , H. E. Aguirre A , D. E. Argudo B C , J. C. Durán C , M. E. Soria A , D. A. Galarza A , H. J. Hernández-Fonseca D and F. P. Perea AA Laboratorio de Biotecnología de la Reproducción Animal, Facultad de Ciencias Agropecuarias, Universidad de Cuenca, Cuenca, Azuay, Ecuador
B Unidad Académica de Ciencias Agropecuarias, Carrera de Medicina Veterinaria, Universidad Católica de Cuenca, Cuenca, Azuay, Ecuador
C Singamia Cia. Ltda., Cuenca, Azuay, Ecuador
D Department of Anatomy, Physiology and Pharmacology, School of Veterinary Medicine, St. George’s University, St. George, Grenada, West Indies
Reproduction, Fertility and Development 35(2) 174-174 https://doi.org/10.1071/RDv35n2Ab95
Published: 5 December 2022
© 2023 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the IETS
This study aimed to assess the effect of adding Knockout Serum Replacement™ (KSR) (ThermoFisher) to the in vitro culture (IVC) on embryo production and blastocyst cryotolerance. Good quality cumulus oocyte-complexes (n = 1798) collected from abattoir ovaries were cultured in a maturation medium (TCM-199 supplemented with 10 ng/mL EGF, 10% fetal bovine serum, 100 UI/mL FSHp, 1 µg/mL oestradiol, 100 µM cysteamine, 50 µg/mL gentamicin), followed by in vitro fertilisation (IVF; semen from a single bull) (FERT-TALP medium with heparin and PHE mix), and IVC (synthetic oviducal fluid medium with amino acids, citrate, and myo-inositol). After IVF, presumptive zygotes were randomly cultured in one of three groups: (1) KSR, 5% of KSR; (2) FBS, 5% of fetal bovine serum; or (3) CON, 0.6% of FAF bovine serum albumin. On Day 7 after IVF, embryos were evaluated and classified into morulae (M), early blastocysts (EB), blastocysts (B), expanded blastocysts (ExB), and hatched blastocysts (HB). Grade 1 embryos were frozen and a representative sample were thawed, then subjected to fluorescent double staining (propidium iodide and Hoechst 33342) to assess the total number of cells and number of cells with an altered cell membrane. Data (from 13 replicates) were analysed by general linear model and least squares means of SAS. Percentages of cleavage, rates of total embryos, rates of M + EB, B, ExB + HB, and the number of total cells and percentage of altered cells after frozen-thawed Day-7 blastocysts are shown in Table 1. In conclusion, supplementation of culture medium with KSR or FBS resulted in (1) similar rates of cleavage, production of total embryos, and B and ExB + HB than CON; (2) lower proportion of developmentally delayed embryos than CON. Addition of 5% KSR to IVC increased cryotolerance of frozen-thawed Day-7 blastocysts compared with FBS, as the proportion of altered cells was significantly lower.
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