Estrous profiling of captive Malayan tapir (Tapirus indicus)

The Malayan tapir (Tapirus indicus) is listed as an endangered species in the International Union for Conservation of Nature (IUCN) Red List, with a global population estimated at fewer than 2,500 mature individuals. In Peninsular Malaysia, the wild population is estimated to range between 1,100 and 1,500. The species is experiencing a rapid decline due to habitat loss, leading to displacement and an increased risk of vehicle collisions. Despite successful captive breeding, the reproductive physiology of the Malayan tapir remains poorly understood, largely due to a lack of studies. This limited knowledge hinders conservation strategies, particularly in the application of Assisted Reproductive Technology (ART) to enhance breeding success in captivity. This study aimed to investigate the estrous profile in captive Malayan tapirs by observing breeding behaviour, vulva score, vaginal cytology, and fecal progesterone hormone analysis. The study was conducted from January to April at the Sungai Dusun Wildlife Conservation Centre, Selangor, Malaysia, involving five female Malayan tapirs aged between 3 and 18 years. Two of these individuals were housed with a male, while the other three were kept individually. Estrus-related behaviours, including vocalization, flehmen response, urine spraying, and excretion smelling, were recorded using closed- circuit television (CCTV) cameras with night vision and audio recording capabilities. Vulva scoring was conducted on a scale of 0 to 4 based on size and the presence of discharge, while vaginal cytology assessed the percentage of vaginal epithelial cells. Fecal progesterone hormone concentrations were analysed using Enzyme-Linked Immunosorbent Assay (ELISA). The results showed that vocalization was the most frequent breeding behaviour (81%), followed by flehmen response (10%), urine spraying (5%), and excretion smelling (4%). Paired females exhibited significantly more frequent breeding behaviours than non-paired females. Meanwhile, vulva scores displayed a cyclic pattern, with a median cycle length of 31 days (range 28 to 33 days). Vaginal cytology also revealed cyclic fluctuations in epithelial cells, with peaks of combined superficial cornified nucleated and anucleated cells exceeding 50%. However, fecal P4 hormone concentrations showed inconsistent fluctuations without a clear cyclic pattern. Spearman’s correlation analysis indicated significant associations under different conditions. When the vulva score was greater than 0, strong correlations were observed between the vulva score and both flehmen response and excretion smelling, as well as between vocalization and urine spraying. When the vulva score was 0, flehmen response showed a strong negative correlation with fecal P4 and a strong positive correlation with excretion smelling. Meanwhile, when vaginal cytology (combination of both superficial cornified nucleated and anucleated cells) was ≥ 50%, the vulva score and fecal P4 had a strong negative correlation, while vocalization and urine spraying exhibited a strong positive correlation. These findings suggest that vulva score and vaginal cytology may serve as reliable indicators of estrus, whereas behavioural observations and fecal progesterone concentration require further investigation to determine their predictive value.

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