There are microbes resident in the reproductive tract, some of which could be pathogenic while a few others would, perhaps, play important roles in protecting the reproductive tract from infections. Volatile compounds are known to play role as sex pheromones that attract the males for coitus during estrus or heat. It is likely that these compounds themselves are secondary metabolites of the bacterial flora resident in the vagina. In order to substantiate this hypothesis, bacteria were isolated from cervico-vaginal mucus (CVM) of buffalo during various phases of the oestrous cycle and identified, based on morphological, biochemical and molecular characteristics, as Bacillus during preestrus as well as diestrus, and Staphylococcus during all phases of the oestrous cycle. But, the populations of Staphylococcus differed between different phases of the oestrous cycle, the predominant forms being S. warneri (BCVMPE1_1) during preestrus, S. pastueri (BCVME2) during oestrus and S. epidermis (BCVMDE3) during diestrus. Mice, when used as sensors, efficiently differentiated the oestrus-specific S. pastueri (BCVME2) from the others. HS-GC-MS analysis showed that S. pastueri (BCVME2) produces key volatile compounds viz., acetic, propanoic, isobutyric, butyric, isovaleric and valeric acids. In addition, it is evidenced that S. pasteuri (BCVME2) volatiles influence the sexual behaviours such as flehmen and mounting of the bull. Thus, the paper reports that S. pasteuri (BCVME2) is the potential source of vaginal pheromone(s) during oestrus in buffalo.