Slipping Membranes.

Slipping Membranes.
The earliest positive sign of pregnancy in the cow, by palpation per rectum, is slipping the chorio-allantoic membranes, generally along the greater curvature. After 50 days of gestation, membranes can be slipped in the contralateral horn as well. In case of bicornual twins, membranes may be slipped as early as 35 days in the cow, and 30 days in the heifer.

Drost M (1982)