Effects of gestagens on the early phases of pregnancy in cattle--clinical experiences. I. Studies on the prevention of embryonic death
Jochle, W.; Jordan, E.; Lohoff, H.; Mauer, M.; Muller, S.; Tschunko, E.
Deutsche Tierärztliche Wochenschrift 83(2): 45-49
1976
ISSN/ISBN: 0341-6593 PMID: 55340 Document Number: 106407
In a double-blind field trial 177 repeat breeder cows or heifers were given 10 mg daily chlormadinone acetate (CAP) or a placebo pellet from 14 to 23 days after artificial insemination or service. On average, the animals had repeated cycling 3.71 times with an average oestrus interval of 24.1 days. CAP in the applied dose had no adverse effect on pregnancy, but a slight increase in conception from insemination (service) before treatment was noted. It did not appear to induce pregnancy after treatment. The well-known luteolytic effect of CAP in cycling animals ceased at the onset of pregnancy. A surprisingly high proportion of the test animals conceived at the last A.I. or service before treatment - 52.9% in the CAP and 46.7% in the placebo group. 62.1% CAP and 61.2% placebo treated animals conceived from service just before, during or after treatment. All biological and clinical data seem to indicate the presence of two different subgroups within the repeat breeder population: one cycling regularly and capable of conception at the third or fourth A.I. or service, the other cycling irregularly at prolonged intervals and with markedly reduced chances of conception. Sterility in this group is high and ovarian cysts are one of the principal causes.