Use of bovine FSH for superovulation and embryo production in beef heifers
1991
Bellows, R.A. | Staigmiller, R.B. | Wilson, J.M. | Phelps, D.A. | Darling, A.
A biologically active dimeric glycoprotein gonadotropin (bFSH) produced by recombinant DNA technology was used to determine superovulation response and embryo production in Hereford F1 and Brahman F1 heifers. Heifers received a total dose of either 18- or 24-mg bFSH administered intramuscularly and given twice daily over a 3-d period. Luteal regression was induced with either dinoprost (Lutalyse) or cloprostenol (Estrumate) administered immediately before the fifth bFSH injection. Blood samples were obtained just prior to the first and fifth bFSH injection and 12 h after the last injection. Progesterone concentrations were determined by radioimmunoassay. Embryos were collected by routine nonsurgical procedures. Superovulatory response (P<0.01) and the number of embryos recovered (P<0.05) were greater in Brahman F1 than Hereford F1 heifers. No significant differences were found due to luteolytic agent or bFSH dosage. Serum progesterone concentration in the initial sample was higher (P<0.01) in Hereford F1 than in Brahman F1 heifers, and there were interactions in progesterone concentrations between heifer breed and bFSH dose (P<0.05) and between breed and luteolytic agent (P<0.05). Residual correlation analyses showed heifers with high progesterone concentrations in the initial sample yielded more normal, quality Grade-1 embryos recovered and frozen (P<0.10 to P<0.05). This new compound had high biological activity and gave an excellent superovulatory response within the dosage range studied. Variation in ovarian-embryo traits was similar to that of presently available gonadotropins.
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