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Title: EFFECTS OF TRANSFERRED OVA PER RECIPIENT AND DUAL USE OF DONORS AS RECIPIENTS ON PRODUCTION OF TRANSGENIC SWINE.

Author
item Pursel, Vernon
item Wall, Robert

Submitted to: Theriogenology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: This study was conducted to determine if the number of gene-injected eggs transferred per recipient influenced the efficiency of producing transgenic pigs and if females that donated the eggs could be used as recipients of eggs. Eight genes were microinjected into 4,232 pigs eggs and then trans- ferred into 169 recipients over a 5 year period. Although the pregnancy rate and litter size was highest for recipients receiving 31 to 41 eggs per recipient, the percentage of transferred eggs developing into piglets was highest for recipients receiving 13 to 20 eggs. Based on these results we conclude transferring more than 20 ova per recipient may incur some loss due to crowding within the late pregnancy. Females used as recipients of microinjected eggs immediately after their own eggs were flushed from their oviducts had the same pregnancy rate, litter size, and egg development efficiency as unmated females that were only used as recipients. However, donor-recipients that ovulated 21 or more eggs had smaller litters and were less efficient in producing pigs and transgenic pigs from transferred eggs than donor-recipients that ovulated 20 or fewer eggs. Dual use of donors as recipients was an effective method of reducing the number of recipients needed in a transgenic project by nearly one-half.

Technical Abstract: The purpose of the study was to determine whether the number of trans- ferred ova per recipient influenced the efficiency of producing transgenic pigs and whether donor gilts were as effective as unmated gilts as recipients of microinjected ova. Eight genes were microinjected into 4,232 ova that were transferred into 169 recipients over a 5 year period. Although the farrowing rate and litter size was highest for recipients receiving 31 to 41 ova per recipient, the percentage of transferred ova developing into piglets was highest for recipients receiving 13 to 20 ova (P = .011 for pregnant recipients and P = .059 for all recipients). Based on these data we conclude transferring more than 20 ova per recipient may incur some loss due to uterine crowding. Gilts used as recipients of microinjected ova immediately after their own ova were flushed from their oviducts had the same farrowing rate, litter size, and ovum development efficiency as unmatead gilts that were only used as recipients. However, donor-recipients that ovulated 21 or more ova had smaller litters (P = .009) and were less efficient in producing pigs (P = .024) and transgenic pigs (P = 0.54) from transferred ova than donor-recipients that ovulated 20 or fewer ova. Dual use of donors as recipients was an effective method of reducing the number of recipients in a transgenic pig project by nearly one-half.