Oocyte source and hormonal stimulation for in vitro fertilization using sexed spermatozoa in cattle

Abstract

The aim of this study was to investigate the efficiency of in vitro embryo production in cattle utilizing sexed sperm from two bulls and oocytes recovered by OPU. Twenty donor animals were employed in eight OPU replicates: the first four OPU trials were conducted on animals without hormone treatment, and the last four were run on the same animals, following FSH subcutaneous and intramuscular administration. A higher rate of blastocyst development was recorded in stimulated, as compared to nonstimulated animals, (25.2% versus 12.8%, P = .001). Ocytes derived from slaughterhouse (SH) ovaries were also fertilized with sperm from the same bulls. Overall, non-sexed sperm used with oocytes derived from SH ovaries was significantly more efficient for blastocyst development than was sexed sperm with these same SH derived oocytes and sexed sperm with stimulated donor oocytes (39.8% versus 25.0% and 25.2%, P = .001). In conclusion, the use of sexed sperm with OPU-derived oocytes resulted in a significantly higher blastocyst development when donors were hormonally stimulated; furthermore, the level of efficiency achieved was comparable to that attained when the same sexed sperm was tested on oocytes derived from SH ovaries.

Figure 1

Weekly scheme and hormone treatment for Ovum pick-up (OPU). (a) The animals were not treated with hormone FSH. Transvaginal OPUs (triangle) were performed on Monday and Thursday of each week for consecutive two weeks, resulting in a total of four sessions. (b) FSH treatment: FSH (arrow) at dosage of 80 mg IM and 120 SC was simultaneously administered on Day 1 (Saturday). Ovum pick-ups were performed 48 and 96 hours post FSH injection, meaning on Day 3 and Day 5 of each week for consecutive two weeks, resulting in a total of four sessions.

Figure 2

Blastocyst yields from the animals subjected to OPU without FSH (open bars) and OPU with FSH treatment (solid bars).