In vitro maturation and embryo production in cattle.

When immature bovine oocytes are released from their follicles and are cultured in standard maturation medium, they resume the first meiotic division. The alteration of basic maturation conditions can affect oocyte competence significantly, as reflected by the morula and blastocyst yield after in vitro fertilization. The conditions used from the beginning of maturation up to the blastocyst stage have been shown to influence not only the developmental competence but also, potentially, the normal epigenetic make-up of the embryo. The methods described in this chapter outline the different steps of in vitro production of bovine embryos up to the blastocyst stage in semidefined conditions: (1) oocyte maturation, (2) in vitro fertilization, and (3) in vitro development. The first section explains procedures of ovary collection and oocyte aspiration and selection for in vitro maturation. The second section involves methods for the preparation of semen and oocytes for fertilization. The last section explains the best conditions to obtain blastocysts after 8 d of in vitro culture.