ABSTRACT
This paper describes a test for diagnosing pregnancy in the cow based on the detection of blastocyst antigens in the maternal blood circulation. Rabbit anti-bovine embryo serum was agglutinated with the sera of non-pregnant cows to obtain specific antibodies. These rabbit antibodies were then absorbed on latex beads which could then be used for the standard passive agglutination reaction. This diagnostic technique was tested on 415 animals. The results on pregnant cows were successful in 78 p. 100 of the cases (confidence interval: 69-86 p. 100) and on non-pregnant cows 94 p. 100 of the time (confidence interval: 90-97 p. 100). This test is independent of the status of the ovaries and of the pregnancy stage. Detection is reliable from day 26 after coitum.