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Effects of administration of two growth hormone–releasing hormone plasmids to gilts on sow and litter performance for the subsequent three gestations

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  • 1 VGX Animal Health Inc., 2700 Research Forest Dr, The Woodlands, TX 77381.
  • | 2 VGX Pharmaceuticals Inc., 2700 Research Forest Dr, The Woodlands, TX 77381.
  • | 3 VGX Pharmaceuticals Inc., 2700 Research Forest Dr, The Woodlands, TX 77381.
  • | 4 VGX Pharmaceuticals Inc., 2700 Research Forest Dr, The Woodlands, TX 77381.
  • | 5 VGX Pharmaceuticals Inc., 2700 Research Forest Dr, The Woodlands, TX 77381.
  • | 6 VGX Animal Health Inc., 2700 Research Forest Dr, The Woodlands, TX 77381.

Abstract

Objective—To determine whether a novel optimized plasmid carrying the porcine growth hormone–releasing hormone (GHRH) wild-type cDNA administered at a lower dose was as effective at eliciting physiologic responses as a commercial GHRH plasmid approved for use in Australia.

Animals—134 gilts.

Procedures—Estrus was synchronized and gilts were bred. Pregnant gilts were assigned to 2 treatment groups (40 gilts/group) or 1 untreated control group (24 gilts). Gilts in one of the treatment groups received the commercial GHRH plasmid, whereas gilts in the other treatment group received a novel optimized GHRH plasmid; both plasmids were administered IM in the right hind limb, which was followed by electroporation. Sow and litter performance were monitored for the 3 gestations after treatment.

Results—A significant increase in insulin-like growth factor-I concentrations, decrease in perinatal mortality rate, increase in the number of pigs born alive, and increase in the weight and number of pigs weaned were detected for both groups receiving the GHRH-expressing plasmids, compared with values for the control group. Additionally, there was a significant decrease in sow attrition in GHRH-treated females, compared with attrition in the control group, during the 3 gestations after treatment.

Conclusions and Clinical Relevance—Both of the GHRH plasmids provided significant benefits for sow performance and baby pig survivability for pregnant and lactating sows and their offspring during the 3 gestations after treatment, compared with results for untreated control gilts. Use of a novel optimized plasmid reduced the effective plasmid dose in these large mammals.

Contributor Notes

Dr. Khan's present address is Inovio Pharmaceuticals Inc, 1787 Sentry Pkwy W, Bldg 18, Ste 400, Blue Bell, PA 19422.

Dr. Draghia-Akli's present address is European Commission, CDMA 02/169, Brussels, Belgium B-1049.

Supported by VGX Animal Health Inc, a subsidiary of Inovio Pharmaceuticals Inc.

The authors thank Karen S. Rosenbaum and Raymond W. Rosenbaum for assistance with the animals.

Address correspondence to Dr. Kern (dkern@vgxah.com).