Two trials were conducted to determine the effects of progesterone administered by controlled intravaginal drug release devices (CIDRs) on pregnancy rates and serum progesterone concentrations in heat stressed dairy cows. Trial 1 utilized a CIDR from days 5 through 12 after breeding, and trial 2 utilized a CIDR from days 5 through 19 after breeding. Rectal temperatures and blood samples were obtained from cows every other day throughout the trial. Serum progesterone concentrations were measured with radioimmunoassay (RIA). Pregnancy status was determined on approximately day 30 via transrectal ultrasonography. Mean temperature-humidity index (THI) values were 73.5 for trial 1 and 75.1 for trial 2. These THI values indicated that cows in both trials were subjected to mild heat stress conditions. No significant differences were found between CIDR treated and control cows in serum progesterone concentrations. In trial 1, pregnancy rates were 31.8% vs. 33.3% for control and CIDR treated cows, respectively (p = 0.25). In trial 2 pregnancy rates were 33.3% vs. 26.7% for control and CIDR treated cows, respectively (p = 0.29). In conclusion, supplemental progesterone administered to heat stressed dairy cows after breeding did not improve pregnancy rates or increase serum progesterone concentrations.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-04272006-103904 |
| Date | 08 May 2006 |
| Creators | Carothers, Randolph Erwin |
| Contributors | G.W. Smith, M.E. Hockett, P.W. Farin, C.S. Whisnant |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-04272006-103904/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto 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 NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, 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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