Submission Number: GIL-4-18-16

Abstract Number: 535

EFFECT OF THE VOLUME OF MEDIUM AND NUMBER OF OOCYTES DURING IN VITRO FERTILIZATION ON EMBRYO DEVELOPMENT IN PIG.

MA Gil 1, Lalantha Abeydeera* 2, JM Vazquez 1, J Roca 1, EA Martinez* 1 and Bill N Day* 2

Department of Animal Pathology, University of Murcia, Spain 1
Department of Animal Sciences, University of Missouri, Columbia, MO 2

Abstract:
The progress toward efficient in vitro production of porcine embryos has been limited by the high incidence of polyspermy and the low rate of embryo development. The aim of this study was to determine if embryo development could be improved by modifying the volume of medium (VM) and the number of oocytes (NOOC) during in vitro fertilization (IVF). Immature oocytes were cultured for maturation (50 oocytes/500 L droplet), fertilization and development as described by Abeydeera and Day (Biol. Reprod. 57:729-734, 1997). Groups of 15, 30 or 50 oocytes were transferred to 2 mL, 1 mL or 100 L of modified TBM medium and inseminated with frozen-thawed spermatozoa (2,000 sperm cells/oocyte) in a 3 x 3 factorial experiment. A total of 2,739 oocytes from 4 replicates were exposed to the sperm for 6 h and then cultured for 6 h (pronuclear formation) or 7 days (blastocyst formation; BF). The results were analyzed by ANOVA and are expressed as mean SEM. The efficiency of fertilization (EF; number of monospermic oocytes/total number of inseminated oocytes) and BF decreased (P<0.025) as the VM increased (EF: 45.942.23%, 43.822.60% and 36.901.57% and BF: 29.382.66%, 23.231.81% and 19.892.13% for VM 100 L, 1 mL and 2 mL, respectively). The BF, but not EF, was also affected (P<0.04) by NOOC (19.791.56%, 28.142.32% and 24.572.85% for groups of 15, 30 and 50 oocytes, respectively. The effect of the interaction VM x NOOC on EF and BF was not significant. In conclusion, when 2,000 sperm/oocyte are used, a low volume of IVF medium (100 L) and an elevated number of oocytes during IVF (30-50) improves the efficiency of in vitro pig embryo production. Supported by grant from DGES (PNFPI/96) and EUREKA (EU1713) project. .

Keywords: in vitro fertilization, pig, oocytes, embryo development

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This abstract is being presented at: 8:00 AM in session:
IVF /ART II