Identification of urinary sex pheromones in female buffaloes and their influence on bull reproductive behaviour

The present study was carried out to identify the urinary sex pheromones of buffaloes and their role in relation to bull reproductive behaviour. Urinary samples were collected from 12 buffalo heifers at four different phases of estrous cycles. Fourteen compounds were identified throughout the cycle, which included phenol, ketone, alkane, alcohol, amide, acid and aldehyde. Among the 14 chemical profiles, three compounds were only found on the day of estrus, viz. 1-chlorooctane, 4-methylphenol and 9-octadecenoic acid. Behavioural investigation clearly showed that bulls were attracted and exhibited repeated flehmen behaviour towards the 4-methyl phenol. The bulls displayed penile erection and mounting behaviour while exposed to 9-octadecenoic acid. However, the other compound, 1-chlorooctane, did not influence such sexual behaviours. The present results provide evidence that the estrus-specific urinary volatile compounds appear to be sex pheromones which initiate the bull’s reproductive behaviour.