Abstract: Simple and accurate early pregnancy diagnosis is an important means to reduce open cows, improve female fecundity and improve farm economic benefits. Although traditional pregnancy diagnoses methods such as rectal palpation, B-ultrasound examination, and progesterone detection have provided important technical support for breeding production, they have not yet achieved the earliest detection of cows after mating, and some farms are still difficult to meet the high technical requirements or laboratory conditions. Pregnancy-associated proteins (PAGs) are pregnancy-specific proteins secreted by embryonic trophoblast cells, which play an important role in the pregnancy of dairy cows and are widely used in the diagnosis of early pregnancy in dairy cows. This article briefly summarizes the existing diagnostic methods for pregnancy, discusses the development process of PAGs diagnostic methods in detail, looks forward to the future development direction of pregnancy diagnostic technology, and makes important progress in "early", "accurate" and "simple", and provides relevant research information and important reference.

Key words: early pregnancy diagnosis, bovine pregnancy-associated protein, automation, mid-infrared spectroscopy