Salivary cell-free and transcripts as potential biomarkers for estrus identification in buffaloes ().

Estrus detection is a major problem in buffaloes because of the poor expression of estrus signs leading to low reproductive efficiency. Salivary transcripts analysis is a promising tool to identify biomarkers; therefore, the present study was carried out to evaluate their potential as estrus biomarkers. The levels of , , , transcripts were compared in saliva during estrous cycle stages [early proestrus (day -2, EP), late proestrus (day-1, LP), estrus (E), metestrus (ME) and diestrus (DE)] of cyclic heifers ( = 8) and pluriparous ( = 8) buffaloes by employing quantitative real-time polymerase chain reaction (qRT-PCR). The levels of (EP/DE 1.46-2.43 fold, LP/DE 2.49-3.06 fold; E/DE 7.21-11.9-fold  < 0.01; ME/D 1.0-1.16 fold) and (EP/DE 0.93-2.39 fold, LP/DE 2.68-3.23 fold; E/DE 8.52-15.18 fold  < 0.01; ME/D 0.86-1.01 fold) were significantly altered during the estrus than other estrous cycle stages in both cyclic heifers and pluriparous buffaloes. Receiver operating characteristic curve analysis revealed the ability of salivary (AUC 0.96;  < 0.001) and (AUC 0.99;  < 0.01) to differentiate E from other stages of the estrous cycle. Significantly higher levels of and transcripts in saliva during the estrus phase suggest their biomarkers potential for estrus detection in buffaloes.