IN-VITRO DEVELOPMENT OF BOVINE EMBRYOS AS AFFECTED BY DIFFERENT LOTS OF BOVINE SERUM-ALBUMIN AND CITRATE

The effect of bovine serum albumin (BSA) lots on the development of in vitro-derived bovine embryos in synthetic oviductal fluid was investigated. Citrate concentration was determined for each lot of BSA, and then correlated with differences noted in the ability of BSA lots to support embryo development. Development of bovine embryos to the blastocyst stage was also compared after culture in chemically-defined medium with varying levels of citrate. There were distinct differences in the ability of the different BSA lots to support embryo development to the blastocyst stage (P less than or equal to 0.05). Citrate content (based on 3.2% BSA) of the medium varied from 320 to 1280 mu M. Although there was an overall linear trend (P < 0.001) for increased number of blastocysts with increasing concentrations of citrate in the medium, there were also substantial deviations (P = 0.024) from this linear trend, suggesting that factors other than citrate could be responsible for stimulating blastocyst development. In the second experiment, the percentages of cleaved embryos that developed to the blastocyst stage in defined medium with 0, 100, 300 or 900 mu M citrate ranged from 18.2 to 27.8% and were similar among treatments (P = 0.441). The mean number of cells in the embryos developing to the blastocyst stage did not differ among treatments (P = 0.545). Overall, these results indicate citrate has little affect on development of bovine embryos to the blastocyst stage in vitro.