POTENTIAL USE OF OVUM PICK-UP FOR EMBRYO PRODUCTION AND BREEDING IN CATTLE

The efficacy of transvaginal ultrasound-guided puncturing of ovarian f ollicles for collecting immature oocytes in cattle was studied. Three experiments were conducted to examine the effects of puncturing on fol licle recruitment and on the number of oocytes collected. Puncture ses sions were executed twice weekly at regular intervals of 3 and 4 d res pectively. The oocytes were matured, fertilized and allowed to develop in vitro and the number of transferable embryos was recorded. The hea lth of the cows was checked daily. In Experiment 1, dairy cows (n=10) were punctured over a period of 5 mo, and the collected oocytes were f ertilized with the semen of 1 bull. In Experiment 2, oocytes were coll ected from one 12 year old high pedigree dairy cow and an one month pr egnant cow were punctured. The oocytes of the old cow were fertilized with semen of 8 different bulls. In Experiment 3, beef cows (n = 6) we re punctured over a 2 mo period and the semen of 2 different bulls of the same breed was used to fertilize the oocytes from 3 of these cows. In Experiment 1, 14.5 +/- 0.4 (mean +/- SEM) follicles were punctured per session, and 8.0 +/- 0.3 (mean +/- SEM) oocytes were recovered. A mean of 16% of the oocytes developed into transferable embryos with a pregnancy rate of 40%. The results did not differ between the months of the experiments, indicating that the transvaginal puncturing method can be used successfully over a 5 mo period. No detrimental effects w ere observed after clinical and post mortem examinations, nor did bree d, age or reproductive status appear to affect the results. However, l arge differences were observed between individual cows and between cow /bull combinations.