Abstract
Precise and early pregnancy detection is crucial for better breeding management and enhancing the overall production of ruminant livestock. Throughout the years, numerous methods have evolved for pregnancy detection in ruminants, each possessing specific advantages and limitations. This review thoroughly discusses both traditional and emergent diagnostic methods, emphasizing their principles, implementation, merits and challenges. Behavioral observation, rectal palpation and ultrasonography are the traditional approaches widely used because of their accessibility and direct detection of pregnancy conditions. Progesterone measurement, pregnancy-associated glycoprotein detection, and estrone sulfate examination are the hormonal assays that provide biochemical proof at specific phases of gestation. Recently, the analysis of interferon-stimulated gene expression and circulating microRNAs has shown promising roles in early pregnancy detection at the genetic and transcriptomic levels. The investigation of volatile organic compounds is a novel approach in pregnancy diagnosis, though it is non-invasive, and further confirmation is required for regular application. This review highlighted the importance of incorporating multiple examination strategies to enhance the accuracy and reliability of pregnancy detection in ruminants. Future research should center on the refinement and field application of advanced technologies to ensure their proper implementation in diverse ruminant production systems.