Identification of potential pheromone source in sows

Pheromones play a pivotal role in intra-species communication for reproduction and social behavior in a variety of mammals, such as boars. For boars, saliva is a rich source of pheromones, however, the identification of additional sources and relative abundance of pheromones in various body fluids of sows is also essential to understand the reproductive behaviors of pigs. The present study was designed to identify the source(s) of pheromones in sows. We collected urine, feces, saliva and cervical mucus/vaginal wash samples from sows at pre-estrus, estrus and post-estrus phases, and from gilts and exposed boars to each of these potential sources of pheromones. All the boars tested spent more time sniffing and hyper-salivating in response to urine from sows in estrus than that from sows not in estrus. The sniffing behavior of boars towards estrus samples differed from that towards the samples from non-estrus sows (P < 0.005) and gilts (P < 0.001). Further, hypersalivation behavior of boars differed between estrus samples and gilt samples (P < 0.05) and estrus samples compared to pre-estrus samples (P < 0.05). This is an indication that pheromones are abundant in the estrus samples. We conclude that urine of estrus sows can be a rich source of pheromones and the same can be used to identify, purify and characterize novel pheromone molecules.