مرکز منطقه ای اطلاع رساني علوم و فناوري - Cryo-preservation of sperm and embryos in small ruminants

Abstract :

Cryo-preservation of sperm and embryos is an important biotechnology for preservation and propagation of genetics. The aim of this paper is to review established procedures and recent advances in sheep, goats and some wild small ruminants. The use of frozen-thawed semen is more common in goat than in sheep. This is primarily due to the need for laparoscopic insemination in ewes. The major difference between sheep and goat is in the behavior seminal plasma towards egg yolk proteins. Recently, research focused on development of new approaches to improve freezing extenders by eliminating animal products such as eggyolk and milk from extenders and their replacement by lecithins from vegetal origin, testing new cryo-protectant and reducing the effects of oxidative stress. The effect of these factors can be tested now more rigorously through the use of various morphological and function techniques such as fluorescent stains, hypoosmotic stress and computerized semen analysis to detect DNA stability, membrane integrity and motion parameters. Small ruminant embryos have been cryopreserved by the slow-cooling technique, which is being slowly replaced by vitrification. In sheep, morulae and early blastocyst are more suitable for freezing. Whereas in goat, expanded blastocysts and hatched blastocyst produce better results. Pregnancy rates after transfer of cryopreservation sheep and goat embryos yields acceptable results when management of recipients and transfer techniques are performed adequately.