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The ability to produce oocytes from genetically valuable, pregnant donors in a safe, repeatable manner would broaden the application of in vitro fertilization (IVF) procedures for beef and dairy cattle. The objectives of this study were to evaluate two gonadotropin treatment schedules for follicle stimulation of pregnant donor cattle and to determine the efficacy and safety of the repeated oocyte aspiration procedure from pregnant cattle. In Exp. 1, pregnant donors at 60 to 90 d of gestation were randomly allotted to three treatment groups. Cows in Treatment A received a total dose of 40 mg of FSH. Cows in Treatment B were administered a total of 20 mg of FSH, and females in Treatment C served as pregnant vehicle-treated controls. A group of luteal phase cows received a total of 40 mg of FSH and served as nonpregnant controls (Treatment D). Ultrasound-guided transvaginal oocyte aspiration was performed 12 h following the last FSH or saline injection. Following follicle aspiration, oocytes were matured for 24 h and then entered a standard bovine IVF procedure. Experiment 2 was conducted to determine the repeatability of this procedure on first trimester cows. Cows in Exp. 2 were selected (after a 20-d recovery period) from each of the three pregnant treatment groups in Exp. 1 and each given 40 mg of FSH before a second oocyte aspiration procedure. The number of follicles aspirated per cow in treatment groups receiving the high FSH dose treatment (40 mg of FSH total dose) was not different (Treatment A, Treatment D, and cows in Exp. 2).(ABSTRACT TRUNCATED AT 250 WORDS)

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These experiments were conducted to evaluate the ability of different somatic-cell monolayers or conditioned medium from somatic cells for supporting bovine embryo development in vitro. In the first experiment, bovine embryos (2- to 4-cells) were allocated randomly to a control (medium 199 with 10% fetal bovine serum and antibiotics) group or co-cultured with bovine oviduct epithelial (BOEC), buffalo rat liver (BRL), Madin Darby bovine kidney (MDBK) or African green monkey kidney (Vero) cells. In the second experiment, bovine embryos (1-cell) were allocated randomly to the following groups: control medium or conditioned medium from BOEC, BRL, MDBK and Vero monolayers. In both experiments, development to the blastocyst stage was assessed after 8 days of incubation at 39 degrees C and 5% CO2. In Experiment 1, coculture improved development to the blastocyst stage compared with control medium alone, and the highest development was observed after co-culture with BOEC. In Experiment 2, conditioned medium enhanced development to morulae and blastocysts compared with the control medium; however, no differences were detected among different cell supports. These results indicate that both co-culture and conditioned medium from different cell monolayers supported development to the blastocyst stage at a higher efficiency than control medium alone.

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