Chulalongkorn Researchers Develop World's First Synthetic Boar Pheromone

Chulalongkorn University's veterinary research team has developed the world's first synthetic pheromone derived from boar scent to help commercial pig farmers successfully stimulate breeding readiness in young sows while reducing disease risks from direct contact with breeding males.

Professor Dr. Phet Thammaruk, head of the research team and chair of the Department of Obstetrics, Reproductive Medicine, and Reproductive Science at Chulalongkorn's Faculty of Veterinary Science, explained that young sows are typically stimulated to reach reproductive maturity around 160-200 days of age. If they don't show estrus during this window, they're removed from the breeding program and sent to meat production, causing farmers to lose significant economic investment, time, and farm resources—even though the sows have never been pregnant.

The global standard method for naturally stimulating reproductive systems is "boar contact," where young sows are exposed to a mature male pig. However, this method has significant limitations. Dr. Phet noted that "boar contact" isn't merely visual—it involves all sensory perceptions, including hearing the boar's vocalizations, smelling its scent, and physical contact like snout-to-snout contact.

Yet the traditional boar contact method faces substantial challenges in safety and labor management. Introducing a full-grown male pig is difficult; mature boars are large, strong, and sometimes aggressive, requiring handlers with specialized animal control expertise. There's also serious disease risk, particularly African Swine Fever (ASF), which currently has no vaccine or cure. If an infected boar is used to stimulate females, the entire farm could be compromised.

Professor Dr. Phet further explained that scent is one of the most important sensory channels for transmitting chemical signals and pheromones, which play a critical role in triggering female sexual behavior.

Dr. Isanya Weesuangsukulthai, a specialist in chemical communication and postdoctoral researcher at the Department of Obstetrics, Reproductive Medicine, and Reproductive Science at Chulalongkorn's Faculty of Veterinary Science, noted that individual young sows may respond differently to boar scent. Citing Canadian research, she explained that some sows don't respond to one boar but display mating behavior with another—likely due to differences in olfactory receptors and how their brains process scent signals, even when exposed to the same chemical compounds.

Professor Dr. Phet added that although pigs lack sweat glands, boars still release certain chemicals through other secretions, particularly saliva, which may contain pheromones related to sexual communication.

The research team collected "natural scent" samples from five breeding boars—including saliva, urine, secretions from the preputial pouch, and genital area scent—to analyze their chemical composition. All samples were analyzed in the laboratory using gas chromatography (GC) to isolate volatile organic compounds (VOCs).

Dr. Isanya explained the findings: "Secretions from multiple sources collected from breeding boars share approximately 80 percent of their chemical composition. Interestingly, most of the detected scents have pleasant woody-green tones rather than the unpleasant odors commonly assumed." From this analysis, the research team selected 23 promising scent compounds for the synthetic formula.