The difficulty of devising a standard treatment regime for cattle which would predictably terminate pregnancies in the 200 to 250 day range is described. Eight 15-month-old heifers which had been accidentally mated when approximately eight months old were examined by rectal palpation and condition scored. To induce abortion an intramuscular injection of 20 mg dexamethasone phenylpropionate was given followed 11 days later by an intramuscular injection of 500 microgram cloprostenol. A record was made of the time of calving along with calving and post calving details. Two of the heifers aborted before the injection of cloprostenol. The other six aborted within 48 hours of receiving this injection. The practical problems associated with aborting immature cattle are discussed as well as the financial aspects.
The objective of this project was to study the effects on pregnancy rates of inseminating estrussynchronize d heifers either at observed estrus or at a fixed time. In April, 1994, 574 yearling crossbred heifers, located on six Kansas ranches, were inseminated to achieve this objective. Her d size ranged from 38 to 293 head. The heifers were synchronized with the MGA-prostaglandin (PGF) system. Heifers were either inseminated 12 hr after the onset of estrus or, if not showing estrus, 72 hr after PGF. Pregnancy rates of 491 heifers bred on estrus averaged 56.6% (39.2 to 80.4%). Pregnancy rates for the 83 fixed-time-inseminated heifers average d 39.8% (15.6 to 56.5%). Heifers that responded to the MGA-PGF synchronization system with a standing heat had higher pregnancy rates than those that were inseminate d at a fixed time. However, fixed-time inseminations used in conjunction with inseminations made at estrus increased the total number of heifers bred to proven AI sires.
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