Abstract
The aim of this study was to evaluate the therapeutic effects and safety of progesterone releasing intravaginal device (PRID) in the treatment of inactive ovaries in dairy cattle. The possible influence of PRID on metabolic and/or health status was also examined. A total of 30 anestrous Holstein-Friesian cows, which on rectal palpation had small, flat and smooth or rounded ovaries were used for the experiment. PRID or placebos were inserted into the vagina and left in place for 12 days. Four animals lost the intravaginal device and one was culled. At the time of PRID insertion, the other 25 animals were divided in two groups: 18 with a progesterone concentration ≤1.0 ng/ml (group A), of which 16 were treated with PRID and 2 with placebos, and 7 with a progesterone concentration >1.0 ng/ml (group B), of which 5 were treated with PRID and 2 with placebos. Of the 16 treated animals in group A, 8 (50%) had a corpus luteum (CL) within 14 days after PRID removal. Of the 5 treated animals in group B, 3(60%) had a CL within 14 days after PRID removal. The mean interval from PRID removal to estrus was 2.7 ± 0.3 and 3.0 ± 1.0 days (± SE) in group A and B, respectively. The conception rate of cows in group A that recovered after treatment with PRID, was 28.6%. No significant changes were observed in hematocrit (Ht), WBC and serum levels of glucose, BUN, AST and ALT at the time of PRID insertion and removal, both within and between animals that recovered and those that did not. PRID is an effective treatment for inactive ovaries in dairy cattle and does not adversely affect metabolic and/or health status of animals. Further study is required to improve conception rate at the induced estrus.
