we called it bumping, did it every month when we were dairying, seems that they needed to be at least 6 months bred before you could tell for sure. took some to be palpated when we were not sure but thought we might have hit something and usually got a 5+ or 6
All ways worked for me, after 1/2 way along, on horses/cattle/sheep/goats - BUT by that time I could usually tell by Looking.
One time I looked at a mare and told an "Old Time good Horseman" not to ride her - He said No Way and did a Bump test - then rode her all day in the Hills. The next AM she had a pretty "Buckskin Colt" at her side.
All animals including Women get a "Glow To Them" and I'm more often Right than Wrong.