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United States Department of Agriculture

Agricultural Research Service

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2010 Annual Report

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.

3. Progress Report
This was the second 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 27 ewes was again synchronized using a controlled intravaginal drug release protocol (CIDR) and pregnant mare serum gonadotropin (PMSG) to induce ovulation (CIDR is a progesterone releasing device that releases the hormone slowly over a number of days and PMSG is a hormone). Artificial insemination of the ewes was performed using our adapted insemination device. Because of issues with the post-thaw quality of the semen and because of the lack of response to the synchronization protocol only one ewe conceived (4% fertility). These results indicate two important points for further research. First, because of the poor response to the estrous synchronization protocol, and based on other recently published reports, the CIDRs will no longer be used in favor of a naturally occurring estrous. Second, higher quality semen must be used to guarantee higher fertility. This can be achieved by collecting and freezing semen from the rams earlier in the season. Therefore, future experiments will incorporate both of these ideas into the experimental design. Project progress is monitored by regular phone contact, by a site visit in December 2009 for performance of the research, and by email.

4. Accomplishments

Last Modified: 06/25/2017
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