Equine Oocyte Recovery and ICSI in Clinical Practice: What Can I Expect?

Embryo production by ICSI is becoming a common clinical procedure in the horse, but little information is available on the expected outcomes of this procedure. Our clinical ICSI program at Texas A&M University sees about 450 cases per year (case = all the oocytes recovered from the ovaries of a mare on one aspiration session), both of oocytes recovered from immature follicles and those recovered from the dominant stimulated follicle. Over half of these cases are of oocytes shipped to the laboratory by referring veterinarians. The average number of oocytes recovered per aspiration of immature follicles at Texas A&M University is seven; after in vitro maturation this yields 4.5 mature oocytes per aspiration. The blastocyst rate achieved is 23% per injected mature oocyte, or about one blastocyst per aspiration session. Approximately half of these blastocysts produce ongoing pregnancies after transfer, for about one foal produced for every two aspiration sessions performed. These averages reflect only the findings of our laboratory; other laboratories may have different results ...