Agricultural Research Service studies in Fort Collins, Colorado found that sheep semen can be collected and shipped - in cooled liquid form - overnight before freezing without harming its in-vitro quality. Researchers also found that the semen could be frozen after shipping without reducing its success in surgical AI.
These studies also compared semen that had been cryopreserved after collection to semen that had been frozen after 48 hours - the time required to ship samples across the country. No differences were observed in semen quality, fertilization ability, or number of lambs born to ewes surgically inseminated with the samples. Potentially, this could open the door to sheep producers to use of samples from around the world, expanding and improving their breeding options.
On another front, researchers also adapted a swine insemination method for use in ewes. It involved using a spiral insemination catheter to traverse the ewe's cervix and deposit thawed semen directly into the uterus. The method takes about two minutes per sheep and costs $1.29. Though faster, less costly and easier, the new method so far has had a lower success rate: about 55% using fresh semen and 10% using frozen semen.