For the bovine in vitro fertilization, oocytes are collected from the follicles or oviduct right after ovulation and incubated in the culture medium for 1 - 28 hours at 37° - 39℃ before being fertilized. Sperm cells are collected by artificial vagina after ejaculation or from the epididymis and washed in the culture medium by centrifugation and incubated for 1 - 6 hours before being inseminated under the similar conditions of oocyte incubation. After the 18 - 48 hours co-culture of sperm cells with oocytes, fertilized eggs are evaluated (and transfered to recipeints, if it is necessary).