Trauma to the Blood Supply.

Trauma to the Blood Supply.
The blood supply to the amniotic vesicle along the lesser curvature is relatively fragile, especially for the early vesicle. Once disrupted the embryo / fetus loses its blood supply and dies. Rough handling can also lead to complete rupture of the amniotic vesicle. This is sometimes used as a method for terminating pregnancy in feedlot heifers.

Drost M (1982)