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Title: IMPROVEMENT OF OVULATED PIG OOCYTE PRODUCTION USING TRANSCUTANEOUS ULTRASONOGRAPHY

Author
item KING, T - ROSLIN INSTITUTE
item Dobrinsky, John
item BRACKEN, J - ROSLIN INSTITUTE
item WILMUT, I - ROSLIN INSTITUTE

Submitted to: Veterinary Record
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Oestrus synchronisation and superovulation increase oocytes obtained, however onset and duration of ovulation is variable across females. Our objective was to improve customized production of ovulated pig oocytes within a defined time window using transcutaneous ultrasonography to determine ovulation in donor animals in early morning. Mature oocytes which were ovulated within 42-48 h post-hCG were preferred for laboratory use. They were obtained from gilts examined prior to 34 h post-hCG and again by 42 h post-hCG to identify the presence of follicles and identify gilts which ovulated early. Scanning continued after the second reference examination for every 2 h until 48 h post-hCG. Ovulation occurred when at least 80% of the follicles could not be detected. Different superovulation protocols affected ovulation and oocyte yield in gilts. Much of the effect was due to a higher percentage of donors in the 42-48h window and a lower percentage of donors with cystic follicles on treatment B compared with A. This effect allowed us to produce a higher number of mature oocytes that ovulate within our window from superovulated pigs. Transcutaneous ultrasonography provided a reliable method to determine scheduled ovulation in gilts allowing selection of superovulation protocols and donors for oocyte production in a somatic cell nuclear transfer program. Further, oocyte donor gilts can be selected independent of their ovulation time, or rejected for low numbers of follicles, no follicular development, or cystic ovaries. This selectivity results in production of more ovulated mature oocytes suitable for nuclear transfer from fewer surgical collections, enabling efficient use of animals for experimentation.

Technical Abstract: Oestrus synchronisation and superovulation increase oocytes obtained, however onset and duration of ovulation is variable across females. Our objective was to improve customized production of ovulated pig oocytes within a defined time window using transcutaneous ultrasonography to determine ovulation in donor animals in early morning. Mature oocytes which were ovulated within 42-48 h post-hCG were preferred for laboratory use. They were obtained from gilts examined prior to 34 h post-hCG and again by 42 h post-hCG to identify the presence of follicles and identify gilts which ovulated early. Scanning continued after the second reference examination for every 2 h until 48 h post-hCG. Ovulation occurred when at least 80% of the follicles could not be detected. Different superovulation protocols affected ovulation and oocyte yield in gilts. Much of the effect was due to a higher percentage of donors in the 42-48h window and a lower percentage of donors with cystic follicles on treatment B compared with A. This effect allowed us to produce a higher number of mature oocytes that ovulate within our window from superovulated pigs. Transcutaneous ultrasonography provided a reliable method to determine scheduled ovulation in gilts allowing selection of superovulation protocols and donors for oocyte production in a somatic cell nuclear transfer program. Further, oocyte donor gilts can be selected independent of their ovulation time, or rejected for low numbers of follicles, no follicular development, or cystic ovaries. This selectivity results in production of more ovulated mature oocytes suitable for nuclear transfer from fewer surgical collections, enabling efficient use of animals for experimentation.