This symposium, sponsored by Bioniche Animal Health and organized by Reuben Mapletoft with assistance from several others, will be valuable for reproductive biologists, veterinary practitioners, and others who deal with the regulation of reproductionin cattle. This is an opportune time to review and reassess embryo production in cattle, including pregnancy, for the following reasons: 1. Numerous tools have become available recently, many pharmacological in nature. 2. There are huge differences amongcattle populations, management systems, and needs that must be dealt with to optimize results. 3. New information is increasing exponentially, and there is an ethical responsibility to use this knowledge wisely; this process will be greatly assisted byinterchanges provided by such symposia. While most of the tools that we now use in the reproductive management of cattle have been available for a decade or more in one form or another, they have moved from the research laboratory to routine use on the farm in new and productive, economical combinations. Examples include ultrasonography, practical hormone releasing devices, and numerous safe and effective pharmaceuticals, particularly the prostaglandins, releasing hormones, and their analogs. A vivid example is current approaches to manipulating estrus and ovulation; these not only are more effective and reliable than past approaches, but they simultaneously are fairly effective at inducing fertile ovulations in anestrous females. Approaches to superstimulation have changed similarly. It now is possible to ignore the stage of the estrous cycle as well as estrus detection without sacrificing the number of normal embryos recovered, and at the same time to repeat procedures in the same animal more frequently than in the past. While the numbers of embryos recovered per attempt has stubbornly not changed much, the number recovered per unit time or per hour invested has increased remarkably. Of course, these procedures require healthy, well-nourished cattle, and compliance by herd managers has become recognized as an important issue.
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