Abstract
In postpartum cows expected to have corpora lutea (CL) of normal (norgestomet-treated) compared to short (control) life spans, function of the largest follicle increases after an increase in concentrations of prostaglandin F 2α (PGF). To determine whether PGF alters follicular growth and subsequent life span of the CL, 43 crossbred beef cows (19 to 22 d postpartum) were assigned to one of four treatments: 1) control (C; n = 10), 2) control + PGF (CPGF; n = 10), 3) norgestomet (N; n = 13), 4) norgestomet + flunixin meglumine (NFM; n = 10). Flunixin meglumine inhibits prostaglandin endoperoxide synthase. On day 0, N and NFM cows received a 6 mg implant of norgestomet. From days 3 through 8, CPGF and NFM cows were injected every 8 hr with 10 mg PGF im or 1 g FM iv, respectively. Implants were removed on day 9. On day 11, each cow received 1000 IU of hCG im to induce formation of CL. Follicular growth was monitored by daily ultrasonography from days 6 through 11. In a majority of the cases ( 25 32 ), the largest follicle present on day 6 was still the largest on day 11; frequency of persistence did not differ with treatment. Rate of growth of the largest follicle was greater in CPGF than in N cows (.6 ± .1 vs .3 ± .1 mm/d, respectively; P < .05) but did not differ between C and NFM cows (.4 ± .1 and .5 ± .1 mm/d, respectively). Concentrations of estradiol in NFM cows were higher (P < .05) on day 3 and declined to concentrations similar to those of the other treatments on day 9. There were no differences among treatments in concentrations of estradiol after implant removal. Proportions of cows forming CL in response to hCG were 8 10 , 8 10 , 8 13 and 6 9 in groups C, CPGF, N, and NFM, respectively and did not differ with treatment. Proportions of cows with normal CL were greater (P < .05) in N than in CPGF ( 4 8 vs 0 8 ) and in NFM than in C ( 5 6 vs 2 8 ). In conclusion, changes in PGF during follicular growth did not play a significant role in the formation of CL of normal life span in postpartum beef cows.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
