Studies On In Vitro Fertilization And Micro-Fertilization And Related Issues In Goats

The goat, as a very important farm species, is characterized by fast growth, good adaptability to different environment and wide-range distribution. However, the quality of the goat breeds present in our country needs improvement. It is well known that artificial insemination, embryo transfer and in vitro fertilization are among the most efficient techniques for the improvement of animal breeds, but they must be studied before practical use. In this study, ovarian oocytes obtained from the slaughterhouse ovaries and matured in vitro were used to study the influencing factors of in vitro fertilization and micro-fertilization. Besides, we also studied extenders and procedures involved in the liquid storage of goat semen. The major results obtained are as follows:1. Goat spermatozoa were best capacitated when incubated in mDM supplemented with 50μg/ml heparin at 38.5 ℃ for 45 min. Co-culture with the mono-layer of caprine oviductal epithelium enhanced goat sperm capacitation.2. There was significant difference in rates of in vitro fertilization among different individual bucks.3. Spermatozoa from the cauda epididymis showed a similar fertility as the ejaculated spermatozoa, but those from the caput and corpus epididymis were inferior in fertility, indicating that goat spermatozoa gained fertilizing capacity during passage through the epididymis.4. Rates of fertilization and morulae/blastocysts in oocytes with fully expanded cumulus were significantly higher than those in oocytes with poorly expanded cumulus. Partial or complete removal of cumulus before fertilization had no effect on fertilization rates of oocytes, but complete removal of cumulus impaired embryo development, leading to reduced morula/blastula rates.5. Spermatozoa from different parts of the epididymis were capable of fertilization and supported embryo development by ICSI, but the fertilization and cleavage rates were significantly lower when sperm from caput and corpus epididymis were injected subzonally.6. Dead spermatozoa were capable of fertilizing oocytes by ICSI, but rates of fertilization and embryo development declined with time after death.7. Without immobilization, treatment with low concentration (0.0005%) of Triton X-100 before ICSI enhanced fertilization and embryo development.8. Activation of oocytes with A23187 or Inomycin/6-DMAP after ICSI markedly improved fertilization and embryo development, and treatments with A23187 or Inomycin/6-DMAP produced similar results.9. Quality of in vitro matured oocytes could be assessed by treatment with 0.3M sucrose.10. Goat semen could be liquid stored in non-yolk (milk) diluents and the rank order for the extenders tested was ANDROHEP > H-M199> ZORLESCO mTyrode>BTS> M2> mDPBS >Tris-citrate solution. The cooling speed that gave the best sperm motility was 3-24 min/℃. The rank order of different temperatures for goat semen liquid storage was 5℃>15℃>20℃ >25℃>38.5℃. The best result of semen liquid storage was obtained when semen was 5-10 times extended. Sperm motility and fertilizing capacity were much improved when the sperm were yolk-coated and the semen plasma was removed soon after collection.