Intergeneric Breeding.
Fertilization occasionally occurs when a doe is bred by a ram, and rare births have been reported. When a ewe is bred by a buck fertilization rarely occurs. Goats have 60 chromosomes, sheep 54.
Drost M (2006)
Sheep-Goat Hybrids.
These fetuses died earlier in gestation due to immunologically incompatible placentation but were not delivered by the doe until approximately 5 months after breeding. Goats have 60 chromosomes, sheep 54. Fertilization occasionally occurs when a doe is bred by a ram, and rare births have been reported. When a ewe is bred by a buck fertilization rarely occurs.
Smith MC (2006)