Semen characteristics and production of germ cells in male sheep-goat chimeras

Semen from 11 male sheep-goat chimeras and one male sheep-goat hybrid-sheep chimera was evaluated on criteria commonly used as in vitro measures of semen quality. In addition, the species origin of germ cells was determined. Five males that were sex chimeras produced spermatozoa only from their XY cells. Three XY/XY sheep-goat males were shown by electrophoretic separation of sperm isozymes to produce both sheep and goat spermatozoa; one male produced live young from both ewes and does inseminated with his semen. The sheep-hybrid male produced only sheep spermatozoa. Significant variation in semen quality was observed among individual males, but semen characteristics were not strictly associated with the maleʹs sex chromosome complement, the species origin of his gametes or the degree of somatic chimerism. These results demonstrate that male interspecies sheep-goat chimeras are fertile and that XY/XY chimeras can produce fertile gametes of both species.