In-vitro fertilization of ruminants.

The first ruminant offspring from in-vitro fertilization was a bull calf born in 1981 (Brackett et aL, 1982). Since then, fertilization has been accomplished in vitro for the three domestic ruminants— cattle, sheep and goats. These developments are largely the result of recent advances in our understanding of oocyte maturation. sperm capacitation and embryonic development. It is the intent of this manuscript to address four questions concerning in-vitro fertilization with primary emphasis on cattle. The questions to be addressed are: (1) what are the uses or reasons for performing WE, (2) can it be done, (3) what are the relative efficiencies of each step and which steps need further development and (4) what are the physiological mechanisms through which the normal in-vivo or in-vitro fertilization process is accomplished.