SUPEROVULATION OF HOLSTEIN HEIFERS BY A SINGLE SUBCUTANEOUS INJECTIONOF FSH DISSOLVED IN POLYVINYLPYRROLIDONE

This study was undertaken to determine whether a single injection of p orcine FSH (pFSH) would induce a superovulatory response in cattle. Ho lstein heifers were given a single injection of pFSH (30mg, sc) dissol ved in saline (Group 1, n=5); 50% polyvinylpyrrolidone (PVP; Group 2, n=5); or 25% PVP (Group 3, n=4). Group-4 heifers (n=5) were given mult iple intramuscular injections of pFSH every 12 h for 3 d at decreasing doses, for a total of 30 mg. All animals received a single injection of 750 mu g PGF(2) alpha 48 h after the initiation of pFSH treatment. Animals exhibiting estrus were artificially inseminated twice througho ut estrus. Ova and embryos were recovered nonsurgically. Ovaries were examined by transrectal ultrasonography or by palpation per rectum on Day 7 or 8 of estrus. Plasma concentrations of pFSH, bovine FSH proges terone, estradiol-17 beta and inhibin were determined by specific radi oimmunoassays. The number of corpora lutes (CL) and the numbers of tot al and transferable embryos which were detected and recovered in Group s 2 and 3 were equivalent to the numbers detected and recovered in Gro up 4. In Group 1, however, only 1 of 5 animals ovulated even a single oocyte. The present study demonstrated that only a single injection of pFSH dissolved in PVP was capable of inducing a superovulatory respon se by maintaing a high plasma FSH concentration to allow for the recov ery of a sufficient number of embryos for transplantation.