Two experiments assessed the potential of altrenogest, an artificial progestogen, and deslorelin acetate, a gonadotropin-releasing hormone (GnRH) agonist, for suppressing estrus and ovulation in cyclic mares. In the first experiment, mares were administered a luteolytic dose of prostaglandin-F2á on d 6 of diestrus, and were then treated with 1 of 3 formulations of altrenogest in slow-release vehicle (6 mares/group): 1) Biorelease altrenogest LA150 (225 mg total as a 1.5 mL injection); 2) Biorelease altrenogest LA225 (225 mg total as a 1.0 mL injection); or 3) Biorelease altrenogest LA225 (450 mg total as a 2.0 mL injection). Six control mares received vehicle. Compared to control mares (10.0 days), time to ovulation was greater (P < 0.01) for all mares receiving altrenogest (17.5 days overall); there was no difference (P > 0.5) among groups receiving altrenogest. Control mares (6 out of 6) first displayed estrus an average of 4.5 days after prostaglandin-F2á injection; of the 18 mares receiving altrenogest, 11 displayed first estrus at an average of 13.5 days (P < 0.02 relative to controls) and there was no difference (P > 0.19) among groups. It was concluded that the 3 formulations of altrenogest were equally effective in delaying estrus and ovulation in cyclic mares. It is suggested that a 10-day injection interval could be used to keep mares out of heat for extended periods of time. The second experiment was similar to the first, except that there were 2 groups: 1) control mares that received a vehicle injection and 2) mares that received an i.m. injection of 1.5 g of deslorelin acetate in biodegradable microparticles. Administration of deslorelin did not affect (P > 0.1) the day of first onset of estrus or the day of ovulation. There was a tendency (P = 0.08) for deslorelin treated mares (3 out of 7 vs. 0 out of 6 controls) to not show estrus at the expected time, even though they experienced luteolysis and ovulation. It was concluded that injection of 1.5 g of deslorelin acetate was not an effective method for suppressing estrus and ovulation in cyclic mares.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-03092012-140419 |
| Date | 14 March 2012 |
| Creators | Stevens, Thomas J. |
| Contributors | Thompson, Donald L., Jr., Williams, Cathleen C., Paccamonti, Dale L. |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-03092012-140419/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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