Effects of gestagens on the early phases of pregnancy in cattle--clinical experiences. 3. 2 double-blind studies under field conditions: attempt at comparative discussion
Jochle, W.; Gunzler, O.
Deutsche Tierärztliche Wochenschrift 83(4): 155-158
1976
ISSN/ISBN: 0341-6593 PMID: 60210 Document Number: 107167
A detailed comparison was undertaken of the results of two double-blind field trials in which the effects of a progestin (chlormadinone acetate - CAP) on early phases of pregnancy, under widely different conditions, were tested. In one trial CAP was evaluated as an early pregnancy indicator; CAP or a placebo was administered in a normal population about 100 days after parturition and 13-17 days after first insemination. In the other trial, in which the drug was administered as a preventative of embryonic loss in repeat breeder cows, CAP or a placebo was applied in a problem population about 160 days after parturition. A comparison of the placebo-treated population showed considerable agreement in the total conception rates and in the percentage of regularly cycling animals; the frequencies of ovarian cysts and of silent heat were rather higher at 100 days after parturition. CAP had little effect on early embryonic losses, nor was it of great value in the early detection of pregnancy (the false positive data rate being too high). In both trials, however, there was a noticeable trend towards improved fertility after CAP application (conception rates were 6.2 - 12.2% higher, and intervals between calving and conception were shortened by 5.2 - 20.2 days). There is, therefore, no scientific case for the use of CAP in early phases of pregnancy, but purely economic considerations may make its use worth-while.