1a.Objectives (from AD-416):
To develop a technique that will enable sheep to be inseminated with frozen-thawed semen using a non-surgical artificial insemination method. Development of this technique will enable sheep producers to better utilize the genetics (semen) of desirable rams for flock improvement and provide the National Animal Germplasm Program (NAGP) with a more efficient, cost effective method for utilizing frozen ram semen samples contained in the repository.
1b.Approach (from AD-416):
The estrous cycle of ewes will be synchronized. Ram semen will be collected and cryopreserved. The ewes will then be inseminated using our newly developed technique at a designated time with fresh or frozen-thawed ram semen. The non-return to estrous rate, the pregnancy rate, and the prolificacy rate (number of lambs born per ewe lambing) will be determined. The results will then be evaluated to refine the techniques to improve the fertility rate in subsequent years.
This agreement has reached the end of its five year life cycle and we made substantial progress in 2012/2013. We focused on. 1)improving the response to the estrous synchronization method; and. 2)comparison of diluents for use with frozen-thawed ram semen. Our research resulted in identification of a better diluent and an estrous synchronization technique. Furthermore, the results from the artificial inseminations using frozen-thawed semen (50% fertility) and the optimized protocols resulted in the same fertility as that achieved using a live ram and estrous synchronized ewes. This is a substantial improvement over prior attempts with frozen-thawed semen which resulted in 10-15% fertility.