Factors influencing {\sl in vitro} fertilization in goats

We studied the effect of buck individuality,epididymal origin of spermatozoa,presence and absence of cumulus during in vitro maturation and fertilization and length of maturation culture on in vitro fertilization and embryo development in goats.The results are summarized as follows:1)semen from different bucks produced significantly different rates of fertilization,cleavage and morulae/blastocysts;2)rates of fertilization,cleavage and morulae/blastocysts by spermatozoa from cauda epididymidis were not different significantly from those of ejaculated spermatozoa but were markedly higher than those of spermatozoa from corpus epididymidis,and those of spermatozoa from corpus epididymidis were significantly higher than those of spermatozoa from caput epididymidis;3)there was no significant difference in fertilization rates among oocytes in vitro matured for 24,27 and 30 h,but fertilization rates of oocytes matured in vitro for 21 h declined significantly;rates of morulae/blastocysts in oocytes matured for 21 and 30 h were significantly lower than rates among oocytes matured for 24 and 27 h;4)rates of fertilization and morulae/blastocysts in oocytes with 3 or 4 grade cumulus expansion were significantly higher than those of oocytes with 0 or 1 grade cumulus expansion;5)mechanical removal of cumulus prior to in vitro maturation severely affected in vitro fertilization and embryo development to morulae/blastocysts of goat oocytes;6)complete or partial removal of cumulus prior to in vitro fertilization did not affect fertilization and cleavage of oocytes,but complete removal of the cumulus significantly decreased the rate of morulae/blastocysts.In summary,in vitro maturation and fertilization of goat oocytes were affected by many factors.