title: Evaluation of systems for collection of porcine zygotes for DNA microinjection and transfer.
abstract: Crossbred gilts and sows (n=116) were used for the collection of 1-cell zygotes for DNA microinjection and transfer. Retrospectively, estrus synchronization and superovulation schemes were evaluated to assess practicality for zygote collection. Four synchronization and superovulation procedures were used: 1) sows were observed for natural estrous behavior; 1000 IU human chorionic gonadotrophin (hCG) was administered at the onset of estrus (NAT); 2) cyclic gilts were synchronized with 17.6 mg altrenogest (ALT)/day for 15 to 19 days followed by superovulation with 1500 IU pregnant mares serum gonadotropin (PMSG) and 500 IU hCG (LALT); 3) gilts between 11 and 16 days of the estrous cycle received 17.6 mg ALT for 5 to 9 days and PMSG and hCG were used to induce superovulation (SALT); and 4) precocious ovulation was induced in prepubertal gilts with PMSG and hCG (PRE). A total of 505 DNA microinjected embryos transferred into 17 recipients produced 7 litters and 50 piglets, of which 8 were transgenic. The NAT sows had less (P < 0.05) ovarian activity than gilts synchronized and superovulated by all the other procedures. Synchronization treatments with PMSG did not differ (P > 0.05) in the number of corpora hemorrhagica or unovulated follicles, but SALT and PRE treaments had higher ovulation rates than LALT (24.7 +/- 2.9, 24.3 +/- 1.8 vs 11.6 +/- 2.7 ovulations; X +/- SEM). The SALT and PRE treatments yielded 12.3 +/- 2.6 and 17.7 +/- 1.7 zygotes. Successful transgenesis was accomplished with SALT and PRE procedures for estrus synchronization and superovulation.
authors.affiliation: Department of Dairy Science Virginia Polytechnic Institute and State University Blacksburg, 24061 USA.
authors.forename: B L
authors.initials: BL
authors.lastname: Williams
authors.forename: A E
authors.initials: AE
authors.lastname: Sparks
authors.forename: R S
authors.initials: RS
authors.lastname: Canseco
authors.forename: J W
authors.initials: JW
authors.lastname: Knight
authors.forename: J L
authors.initials: JL
authors.lastname: Johnson
authors.forename: W H
authors.initials: WH
authors.lastname: Velander
authors.forename: R L
authors.initials: RL
authors.lastname: Page
authors.forename: W N
authors.initials: WN
authors.lastname: Drohan
authors.forename: E T
authors.initials: ET
authors.lastname: Kornegay
authors.forename: R E
authors.initials: RE
authors.lastname: Pearson
authors.forename: T D
authors.initials: TD
authors.lastname: Wilkins
authors.forename: F C
authors.initials: FC
authors.lastname: Gwazdauskas