Adding essential amino acids at a low concentration improves the development of in vitro fertilized porcine embryos

The aims of this study were to investigate improvements to the pig preimplantation embryo culture system using in vitro produced embryos. For experiment 1, the optimum time to change the medium from NCSU23 containing 0.6 mM glucose, 0.2 mM pyruvate, 5.7 mM lactate and nonessential amino acids to NCSU23 containing 5.6 mM glucose and both essential and nonessential amino acids was examined. There were no statistically significant differences in blastocyst rates or cell number when the medium was changed at 48, 72 or 96 h, although there was a consistent trend for the 96 h treatment to produce fewer blastocysts with fewer cells. For experiment 2, the addition of essential amino acids at either a 1:50 or a 1:100 dilution of the purchased stock solution for day 1 to 6 or for days 3 to 6 only was investigated. Adding essential amino acids at a 1:50 dilution for day 3 to 6 significantly reduced the blastocyst rate and adding them at a 1:50 dilution from day 1 to 6 significantly reduced both the blastocyst rate and blastocyst cell number compared to when it was added at a 1:100 dilution. Embryos were produced by IVF, cultured for 6 days and good quality blastocysts were transferred into 6 synchronized pseudopregnant recipients (24 to 35 blastocysts per recipient) resulting in 4 pregnancies and 21 live birth piglets. These results show that adding essential amino acids at a 1:100 dilution provided the best culture conditions and the blastocysts produced were able to attain full term development after transfer.