EVALUATION OF TRANSVAGINAL ULTRASOUND-GUIDED FOLLICLE PUNCTURE TO COLLECT OOCYTES AND FOLLICULAR FLUIDS AT CONSECUTIVE TIMES RELATIVE TO THE PREOVULATORY LH SURGE IN ECG PG-TREATED COWS/

Holstein-Friesian cows (n=56) were synchronized with Syncro-Mate B, an d those cows (n=47) developing a normal progesterone pattern were furt her treated im with 3,000 I.U. eCG at Day 10 and 22.5 mg PGF2alpha 48 h later. Blood samples were collected every hour from 30 until 49 h af ter PG administration. Cows (n=17, 36.2%) with fewer than 8 follicles larger than 8 mm in diameter at 28 to 30 h after PG treatment and anim als without an LH peak (n=7, 23%) were excluded from the study. Transv aginal ultrasound-guided puncture of the follicles was carried out two times per cow, at 30 h after PG injection (4 to 5 follicles) and agai n at 1 to 5 (n=6), 12 (n=8) or 22 h (n=9) after the LH peak. No differ ences in the concentrations of progesterone and LM were observed among the 3 groups. An average of 18 follicles per cow was punctured (total of 415 punctures, n=23); 116 cumulus-oocyte-complexes and 370 follicu lar fluid samples were obtained producing average recovery rates of 28 .0% and 89.2%. The number of cumulus-oocyte-complexes varied between p uncture times; shortly before ovulation, at 22 h after the LH peak, th e recovery rate was significantly 5 times higher than immediately afte r the LH peak. Overall, in 75 punctures the cumulus-oocyte-complex was accompanied by a pure follicular fluid sample (3.3 per cow). In concl usion, the transvaginal ultrasound-guided puncture of preovulatory-siz e follicles can be used to collect follicular fluids to study changes in the microenvironment of maturing oocytes upon superovulation. Howev er, further research is required in order to obtain an equivalent numb er of accompying cumulus-oocyte-complexes.