Chemical Characterization of the Marking Fluid of Breeding and non-Breeding Male Cheetahs

Volatile semiochemicals released, amongst other methods, through marking fluid (MF), and characterized by scent/odor, are involved in communication and identification of an individual. Scent has an important role in reproduction of cheetahs and other felids; in fact, the presence/odor of a male cheetah has been noted to trigger the estrous cycle of females. The objectives of the study were to analyze the MF of male cheetahs from different breeding groups to determine the composition of volatile organic chemicals (VOCs) present. Five males per group (e.g., breeding vs non-breeding) were selected from two facilities. The first facility only had breeding males (B; e.g., animals regularly exposed to females on estrus and actively involved in breeding programs); the second facility, only had non-breeding males (NB). The average age of the B and NB males was of 8.1±2.3 and 6.7±2.8 years respectively. Eighteen MF samples were collected from both groups. VOCs were extracted from the headspace, using solid-phase microextraction techniques and analyzed with gas-chromatography mass-spectrometry. Possible relationships between the frequency of presence/absence of each VOC and the respective groups were evaluated through a contingency test with Fisher’s exact test. Differences in relative concentration (RC) of the identified compounds between groups were analyzed using analysis of variance for repeated measures. Fifty-eight VOCs were identified from the MF, and twelve were commonly identified in the samples collected. The RC of dodecanoic acid and nonanoic acid was significantly greater in the B compared with the NB males; whereas indole tended to be greater in the NB compared with the B group. Although the observed differences could indicate the possible involvement of specific VOCs in reproductive behavior, the different diets and age could have also affected the VOCs RC. Further studies are needed to better understand possible differences in RC of VOCs between breeding groups to confirm their role in reproduction.