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 was the first year of the research to adapt the non-surgical artificial insemination (AI) technique to a small breed of sheep; namely the Black Welsh Mountain sheep. To investigate this adaptation the estrous cycle of 56 ewes was synchronized using a recently described protocol (CIDRs for 5 days followed by two dosages of Lutalyse 48 hours apart). Next, the ridges of spiral swine AI catheters were trimmed to enable ease of insertion into the ewes’ cervices when performing AI. Because of issues with the post-thaw quality of the available semen only fresh semen (N = 14 rams) was used for AI. Ewes were inseminated using the swine catheters 53-58 hours post CIDR removal with 400 million total sperm. The fertility and prolificacy rates were 25% and 1.31 lambs born per ewe lambing, respectively. These results indicate three important points for further research. First, a better estrous synchronization protocol must be determined to enable a better heat response. Secondly, smaller spiral catheters should be made to enable greater entry into/through the cervices of ewes. Third, while the method does enable fertility, meaning there is some success, the protocols must be adapted for use with frozen-thawed ram semen to enable a greater usage of genetics by the sheep industry. Project progress is monitored by regular phone contact, by a site visit in December 2008 for performance of the research, and by email.