A test for early pregnancy in sheep.

The rosette inhibition test has been used to detect an early pregnancy factor (EPF) in the serum of ewes. EPF was shown to be to be present within 72 h of mating and was still detectable after one month of gestation and in some cases after four months' gestation. The detection of EPF could be of value in the diagnosis of pregnancy in the ewe during the first month of gestation.