High bovine blastocyst development in a static in vitro production system using SOFaa medium supplemented with sodium citrate and myo-inositol with or without serum-proteins

We describe a bovine embryo culture system that supports repeatable high de velopment in the presence of serum or BSA as well as under defined conditio ns in the absence of those components. In the first experiment, embryo deve lopment in SOF with amino acids (SOFaa), sodium citrate (SOFaac) and myo-in ositol (SOFaaci) and with BSA or polyvinyl alcohol (PVA) was compared with that in a M199 granulosa cell co-culture (M199 cc-culture). Subsequently, d evelopment and cell numbers of blastocysts cultured under defined condition s in SOFaaci with PVA (SOFaaci-PVA), or under undefined conditions in SOFaa ci with 5% cow serum (SOFaaci-CS) or M199 co-culture were compared. The rep eatability of culture results in SOFaaci-CS was checked by weekly replicate s (n=30) spread over 11 months. The viability of embryos developed in SOFaa ci-PVA was estimated by transfer of morphologically good blastocysts (n=10) to synchronized recipients. In the second experiment, the effect of omitti ng CS or BSA from IVM and IVM-IVF on subsequent embryo development in SOFaa ci-PVA or in SOFaaci-CS was investigated. Blastocyst development in SOFaa-P VA, SOFaac-PVA, SOFaa-BSA and M199 was 16 +/- 3(b), 23 +/- 2(ab), 30 +/- 8( a) and 36 +/-7(a)%, respectively (P-ab < 0.05). Additional inclusion of myo inositol resulted in 42 +/- 1(a)% blastocysts in SOFaaci-PVA vs 19 +/- 3(b) % in SOFaac-PVA, 47 +/- 7(a)% in SOFaac-BSA, and 36 +/- 7(a)% in M199 co-cu lture, respectively (P-ab< 0.01). In 30 replicates, the average cleavage an d blastocyst rates of oocytes in SOFaaci-CS were 87 +/- 4 and 49 +/- 5%, re spectively. Five normal calves were produced after transfer of 10 blastocys ts developed in defined culture medium (i.e., SOFaaci-PVA). Defined IVM or IVM-IVF (i.e., in absence of CS and BSA) reduced cleavage rates (83 +/- 3 a nd 55 +/- 3% vs 90 +/- 1% in presence of CS; P < 0.01). Subsequent embryo d evelopment in SOFaaci-CS was not affected in either of these defined condit ions. However, cleavage and blastocyst rates under completely defined IVP c onditions were 54 +/- 7 and 19 +/- 4%, respectively. It was concluded that under defined culture conditions, addition of citrate and myo-inositol impr oved blastocyst development to rates comparable to those obtained with seru m, BSA or co-culture and that the quality of blastocysts was not affected b y the absence of serum or BSA. However, serum was essential during IVM/IVF for normal fertilization and subsequent high blastocyst development. (C) 19 99 by Elsevier Science Inc.