276INFLUENCE OF SPERM TREATMENTS ON BLASTOCYST DEVELOPMENT IN VITRO AND CELL NUMBER IN CATTLE

Abstract

Experiments were designed to examine the effects of developmental rate and cell numbers in embryos produced by in vitro fertilization (IVF) using sperm from 2 bulls (sperm A and B purchased from commercial sale) isolated by three methods. Cumulus-oocyte-complexes collected from ovaries harvested from a local slaughter house were matured in 50μL droplets of serum-free M199 medium supplemented with 1μgmL−1 estradiol-17β, 10μgmL−1 LH and FSH under silicone oil at 39°C in a humidified atmosphere of 5% CO2 in air. After 24h of culture, oocytes were fertilized with the sperm treated by three different methods of isolation;; percoll gradient, swim-up and glass wool filtration;; a final concentration of 2×106 cells mL−1 was used. At 16h after fertilization, presumptive zygotes were co-cultured in serum-free M199 with BOEC for up to 192h post-insemination. At 48h and 120h post-insemination, the cultures were fed with 25μL of serum-free M199. The embryos were compared for their rates of cleavage at 48h post-insemination, development to the blastocyst stage, and hatching, and also the cell number at 192h post-insemination. Differences between treatments were analyzed using one-way ANOVA after arc-sine transformation of the proportional data of cleavage, development into blastocyst stage and hatching. Comparisons of means among treatments were performed using Tukey-Kramer multiple comparisons test. The results are summarized below. The rates of cleavage in embryos produced by IVF using sperm from 2 bulls isolated by percoll, swim-up and glass wool were not significantly different. The blastocyst development and hatching rates between sperm treatment were not significant within bull sperm A and within sperm B. However, although the hatching rate in percoll treatment of bull sperm A was higher than in bull sperm B, the difference was not statistically significant. The mean cell numbers in percoll treatment of bull sperm A (176.5±7.1) were significantly higher (P<0.001) than the others. In bull sperm B the cell numbers in percoll treatment were higher than the other two treatments, but the differences were not statistically significant. In conclusion, these results support the concept that sperm preparation using percoll has beneficial effects on blastocyst cell number. Table 1 Developmental rates of in vitro embryos using sperm from 2 bulls isolated by three methods with 4 replicates