Early pregnancy diagnosis in water buffaloes through detection of Pregnancy-associated glycoprotein (PAG) in milk using Enzyme-link immunosorbent assay

Abstract

Early pregnancy diagnosis following insemination is an important component of the reproductive management
program to shorten the calving interval in water buffaloes. A recent method to detect pregnancy in dairy animals is
through pregnancy-associated glycoproteins (PAGs) that are present during implantation and throughout the gestation
period. In this study, milk PAG Enzyme-Link Immunosorbent Assay (ELISA) technique was used and run in parallel
with blood PAG ELISA for its efficiency in detecting early pregnancy in lactating buffaloes. Fixed Time Artificial
Insemination (FTAI) was conducted in lactating buffaloes followed by the collection of milk and blood samples postFTAI. Samples were then assayed using commercial PAG ELISA test kits (IDEXX, USA). Trans-rectal ultrasonography
was conducted to confirm pregnancy. Of the 22 inseminated lactating buffaloes, 12 (54 %) were considered pregnant
based on PAG concentration in milk on day 26 and similarly in blood on day 25 post-FTAI. These twelve animals were
all confirmed pregnant by ultrasonography on day 40 post-FTAI. In addition, variation in PAG expressions in milk
samples was observed among animals until at least day 60 of gestation. Essentially, milk PAG ELISA is an accurate
and non-invasive approach to detect early pregnancy in lactating buffaloes which can help reduce the calving interval
and improve reproduction in water buffaloes.