Determination of pregnancy status in cattle and sheep

A method for determining non-pregnancy status in an animal selected from the group consisting of cattle and sheep, comprising determining the level of extra-uterine expression of a pregnancy-induced protein selected from the group consisting of Mx protein and ubiquitin cross-reactive protein in blood collected from the animal during the period 15 to 27 days following breeding of a ewe or 18 to 30 days following breeding of a cow and comparing the level of expression of said protein in the animal to that of a non-pregnant female animal of the same species, wherein an absence of increase in the level of the expression of the protein in the animal compared to that of the non-pregnant animal indicates that the animal is not pregnant.