CLINICAL FINDINGS OF DENTAL DISEASE AND POTENTIAL CONTRIBUTING FACTORS IN PYGMY SLOW LORISES (NYCTICEBUS PYGMAEUS) UNDER HUMAN CARE.

Dental disease is a common finding in pygmy slow lorises (Nycticebus pygmaeus) under human care, but the etiology is not fully understood. The small oral cavity in this species can make diagnosis of dental disease difficult. This retrospective study evaluated medical records and diet and husbandry protocols from 18 participating institutions with the objective of describing the signalment, clinical signs, physical exam findings, tooth type, tooth location, diagnostics used, and treatments performed to help guide care for dental disease. In addition, the study aimed to identify potential contributing factors to dental disease in this species. Of 59 animals with medical records evaluated, 42 (71.2%) had dental disease: 19 (44.2%) males, 20 (46.5%) females, and 3 (9.3%) without gender documented. Average age at onset of dental disease was 7.6 yr in males and 9 yr in females. Multiple lorises with dental disease (n = 12; 28.6%) had no premonitory clinical signs, and dental disease was found incidentally on examination. On dental examination, 30 lorises (71.4%) had evidence of gingivitis. In 13 cases skull radiographs were taken, but the majority of images (n = 8; 61.5%) were nondiagnostic for pathologic dental changes. A small proportion of cases with dental abnormalities (n = 4; 9.5%) were diagnosed using computed tomography. In total, 175 teeth were extracted from 31 patients; molars were the most frequently extracted tooth (n = 55; 31.4%). No substantial differences in diets were noted among many of the participating institutions, and not all slow lorises evaluated developed dental disease (n = 17; 28.8%). This retrospective study provides clinical findings on slow loris dental disease and guidance for the veterinary care and management of slow lorises under human care.

Slowly Making Sense: A Review of the Two-Step Venom System within Slow (Nycticebus spp.) and Pygmy Lorises (Xanthonycticebus spp.).

Since the early 2000s, studies of the evolution of venom within animals have rapidly expanded, offering new revelations on the origins and development of venom within various species. The venomous mammals represent excellent opportunities to study venom evolution due to the varying functional usages, the unusual distribution of venom across unrelated mammals and the diverse variety of delivery systems. A group of mammals that excellently represents a combination of these traits are the slow (Nycticebus spp.) and pygmy lorises (Xanthonycticebus spp.) of south-east Asia, which possess the only confirmed two-step venom system. These taxa also present one of the most intriguing mixes of toxic symptoms (cytotoxicity and immunotoxicity) and functional usages (intraspecific competition and ectoparasitic defence) seen in extant animals. We still lack many pieces of the puzzle in understanding how this venom system works, why it evolved what is involved in the venom system and what triggers the toxic components to work. Here, we review available data building upon a decade of research on this topic, focusing especially on why and how this venom system may have evolved. We discuss that research now suggests that venom in slow lorises has a sophisticated set of multiple uses in both intraspecific competition and the potential to disrupt the immune system of targets; we suggest that an exudate diet reveals several toxic plants consumed by slow and pygmy lorises that could be sequestered into their venom and which may help heal venomous bite wounds; we provide the most up-to-date visual model of the brachial gland exudate secretion protein (BGEsp); and we discuss research on a complement component 1r (C1R) protein in saliva that may solve the mystery of what activates the toxicity of slow and pygmy loris venom. We conclude that the slow and pygmy lorises possess amongst the most complex venom system in extant animals, and while we have still a lot more to understand about their venom system, we are close to a breakthrough, particularly with current technological advances.

Reducing stress and stereotypic behaviors in captive female pygmy slow lorises (Nycticebus pygmeaus).

Improving captive conditions of pygmy slow lorises (Nekaris and Nijman have recently suggested that the pygmy slow loris should be called the pygmy loris and is distinctive enough to warrant a new genus, Xanthonycticebu) (Nycticebus pygmeaus) poses many challenges because detailed aspects of their lives in the wild are incomplete. This hinders efforts to replicate sustainable environments for them. To improve their well-being in captivity, eight rescued female pygmy slow lorises at the Japan Monkey Center (JMC) were socially housed in two types of groups following their solitary housing: two pairs and one group of four individuals. They spent much of their time in affiliative behaviors, as well as sharing sleeping sites after placement in a social group. The purpose of my study was to examine whether social housing helped in reducing stress by comparing fecal glucocorticoids and stereotypic behaviors when housed alone and when with conspecifics. Overall, the levels of fecal glucocorticoids were significantly lower when socially housed than when kept alone. One individual exhibited stereotypic behavior when housed alone, but this behavior disappeared after social housing. These findings support recent evidence that pygmy slow lorises are social animals and will benefit from group housing in captivity. We conclude that social housing of pygmy slow lorises improves their well-being by reducing stress levels, and that their group housing in captivity can provide dividends for the conservation of this endangered nocturnal primate because lorises intended for release should find it easier to adapt to natural conditions.

Welfare assessment of slow loris (Nycticebus spp.) at an Indonesian primate rehabilitation center: Development and validation of body condition score.

Body condition scoring (BCS) assessment can reflect animal welfare status and help the veterinarian to make a quick health management decision, including for confiscated slow loris (Nycticebus spp.). The confiscated slow loris should be rehabilitated in a rehabilitation center before being released. It is essential to monitor the welfare of slow loris to ensure that candidates are released. Assessment of animal welfare status requires representative measurable criteria and indicators. However, there is no standardized BCS for slow loris yet. This study focuses on developing and validating BCS based on body weight and circumference. In this study, 180 individuals were evaluated and scored. We measured body weight and circumferences to validate the assessment of BCS. There are no significant differences in body weight and circumferences within species and sexes. Muscle mass and fat deposits were palpated, visually viewed, and grouped in five BCS. There was a significant difference in body weight and circumference between BCS levels. According to this study, the development of BCS is valid and can be used to slow loris in prevailing circumstances and any ex-situ facilities.

Molecular Phylogenetic Relationships and Unveiling Novel Genetic Diversity among Slow and Pygmy Lorises, including Resurrection of Xanthonycticebus intermedius.

Genetic analysis of historical museum collections presents an opportunity to clarify the evolutionary history of understudied primate groups, improve taxonomic inferences, and inform conservation efforts. Among the most understudied primate groups, slow and pygmy lorises (genera Nycticebus and Xanthonycticebus) are nocturnal strepsirrhines found in South and Southeast Asia. Previous molecular studies have supported five species, but studies using morphological data suggest the existence of at least nine species. We sequenced four mitochondrial loci, CO1, cytb, d-loop, and ND4, for a total of 3324 aligned characters per sample from 41 historical museum specimens for the most comprehensive geographic coverage to date for these genera. We then combined these sequences with a larger dataset composed of samples collected in Vietnam as well as previously published sequences (total sample size N = 62). We inferred phylogenetic relationships using Bayesian inference and maximum likelihood methods based on data from each locus and on concatenated sequences. We also inferred divergence dates for the most recent common ancestors of major lineages using a BEAST analysis. Consistent with previous studies, we found support for Xanthonycticebus pygmaeus as a basal taxon to the others in the group. We also confirmed the separation between lineages of X. pygmaeus from northern Vietnam/Laos/China and southern Vietnam/Cambodia and included a taxonomic revision recognizing a second taxon of pygmy loris, X. intermedius. Our results found support for multiple reciprocally monophyletic taxa within Borneo and possibly Java. The study will help inform conservation management of these trade-targeted animals as part of a genetic reference database for determining the taxonomic unit and provenance of slow and pygmy lorises confiscated from illegal wildlife trade activities.

Breaking the constraint on the number of cervical vertebrae in mammals: On homeotic transformations in lorises and pottos.

Mammals almost always have seven cervical vertebrae. The strong evolutionary constraint on changes in this number has been broken in sloths and manatees. We have proposed that the extremely low activity and metabolic rates of these species relax the stabilizing selection against changes in the cervical count. Our hypothesis is that strong stabilizing selection in other mammals is largely indirect and due to associated pleiotropic effects, including juvenile cancers. Additional direct selection can occur due to biomechanical problems (thoracic outlet syndrome). Low metabolic and activity rates are thought to diminish these direct and indirect effects. To test this hypothesis within the primates, we have compared the number of cervical vertebrae of three lorisid species with particularly low activity and metabolic rates with those of more active primate species, including with their phylogenetically closest active relatives, the galagids (bushbabies). In support of our hypothesis, we found that 37.6% of the lorisid specimens had an abnormal cervical count, which is a higher percentage than in the other nine primate families, in which the incidence varied from zero to 2.2%. We conclude that our data support the importance of internal selection in constraining evolvability and of a relaxed stabilizing selection for increasing evolvability. Additionally, we discuss that there is no support for a role of the muscularized diaphragm in the evolutionary constraint.

Functional genomics analysis reveals the evolutionary adaptation and demographic history of pygmy lorises.

Lorises are a group of globally threatened strepsirrhine primates that exhibit many unusual physiological and behavioral features, including a low metabolic rate, slow movement, and hibernation. Here, we assembled a chromosome-level genome sequence of the pygmy loris (Xanthonycticebus pygmaeus) and resequenced whole genomes from 50 pygmy lorises and 6 Bengal slow lorises (Nycticebus bengalensis). We found that many gene families involved in detoxification have been specifically expanded in the pygmy loris, including the GSTA gene family, with many newly derived copies functioning specifically in the liver. We detected many genes displaying evolutionary convergence between pygmy loris and koala, including PITRM1. Significant decreases in PITRM1 enzymatic activity in these two species may have contributed to their characteristic low rate of metabolism. We also detected many evolutionarily convergent genes and positively selected genes in the pygmy loris that are involved in muscle development. Functional assays demonstrated the decreased ability of one positively selected gene, MYOF, to up-regulate the fast-type muscle fiber, consistent with the lower proportion of fast-twitch muscle fibers in the pygmy loris. The protein product of another positively selected gene in the pygmy loris, PER2, exhibited weaker binding to the key circadian core protein CRY, a finding that may be related to this species' unusual circadian rhythm. Finally, population genomics analysis revealed that these two extant loris species, which coexist in the same habitat, have exhibited an inverse relationship in terms of their demography over the past 1 million years, implying strong interspecies competition after speciation.

The effects of olfactory stimulation on the behaviour of captive slender lorises (Loris lydekkerianus).

Studies on primate sense of smell are scarce, even though odours represent the main communicative channel for many nocturnal primates such as gray slender lorises (Loris lydekkerianus). Here, we investigate the influence of natural odours on communicative and social behaviours on a group of slender lorises housed at the Frankfurt Zoo. Previously collected chemical marks from unknown conspecifics, urine from a natural predator (rusty-spotted cats) and a control setup were introduced in random order to the group enclosure. We recorded chemical communication behaviours, such as marking and sniffing, social behaviours and general activities. Using generalized linear mixed-effect models, we found that the odours did not have an effect on marking, but on sniffing behaviours of the animals. Conspecific odours decreased the sniffing frequencies of the animals (especially shortly after introduction). When predator odours were introduced, sniffing increased when compared to treatments with conspecific odours, but not in comparison to control treatments. The frequency of social behaviours, feeding and self-grooming did not change in response to predator or conspecific odours. Despite some limitations to our study, the data show a trend that natural odours may trigger some interest in group-kept slender lorises, and further examination of other novel odours may be worth studying (e.g. for potential chemical enrichment in zoos).

Postural behavior recognition of captive nocturnal animals based on deep learning: a case study of Bengal slow loris.

The precise identification of postural behavior plays a crucial role in evaluation of animal welfare and captive management. Deep learning technology has been widely used in automatic behavior recognition of wild and domestic fauna species. The Asian slow loris is a group of small, nocturnal primates with a distinctive locomotion mode, and a large number of individuals were confiscated into captive settings due to illegal trade, making the species an ideal as a model for postural behavior monitoring. Captive animals may suffer from being housed in an inappropriate environment and may display abnormal behavior patterns. Traditional data collection methods are time-consuming and laborious, impeding efforts to improve lorises' captive welfare and to develop effective reintroduction strategies. This study established the first human-labeled postural behavior dataset of slow lorises and used deep learning technology to recognize postural behavior based on object detection and semantic segmentation. The precision of the classification based on YOLOv5 reached 95.1%. The Dilated Residual Networks (DRN) feature extraction network showed the best performance in semantic segmentation, and the classification accuracy reached 95.2%. The results imply that computer automatic identification of postural behavior may offer advantages in assessing animal activity and can be applied to other nocturnal taxa.

Habitat suitability modeling for the endangered Bengal slow loris (Nycticebus bengalensis) in the Indo-Chinese subregion of India: a case study from southern Assam (India).

The Bengal slow loris (Nycticebus bengalensis) is an endangered nonhuman primate distributed in Southeast Asia, including India. The species is facing sharp population decline throughout its range, largely due to acute habitat loss and fragmentation. IUCN revised the threatened status of the species from vulnerable to endangered in 2020. In the present study, habitat suitability modeling was conducted in southern Assam (India) to analyze the suitable habitat for the Bengal slow loris. The modeling analysis was performed using MaxEnt software. Using a reconnaissance field survey and questionnaire, data on the presence of 30 Bengal slow lorises were collected and run along with seven biophysical factors. The area under the curve (AUC 0.825) indicated high predictive performance of the model. A jackknife test revealed that all seven biophysical factors were important (scores greater than 0.1). The contribution of forest pattern, normalized difference vegetation index, elevation, slope, distance from cropland, normalized difference built-up index and distance from roads were found to be 35.3%, 34.9%, 9.3%, 5.9%, 5.7%, 4.6%, and 4.3%, respectively. Based on thresholds including minimum training presence, tenth percentile training presence, and equal training sensitivity and specificity, this model indicates that 49.91%, 38.30% and 20.37% of the land, respectively, was suitable for the slow loris in southern Assam. This finding regarding habitat distribution and suitability is essential for identifying priority areas for future research and for focusing survey efforts for the long-term conservation of the species.

The sticky tasty: the nutritional content of the exudativorous diet of the Javan slow loris in a lowland forest.

Plant exudates are an important food source for many primates. The Critically Endangered Javan slow loris (Nycticebus javanicus) was previously found to prefer Acacia decurrens exudate in an anthropogenically disturbed site, while its feeding habits in secondary natural forest remain unknown. Knowledge of the chemical characteristics of the plant exudates that Javan slow lorises consume is limited, especially with respect to those that they feed on in natural forests. As plant exudates may contain plant secondary metabolites (PSM), which are considered unpalatable in high concentrations, differences in PSM composition may drive feeding preferences. This research aims firstly to confirm exudate consumption by the Javan slow loris in a lowland tropical forest in Central Java, and secondly to identify the chemical characteristics of the exudates consumed. We followed wild slow lorises in Kemuning Forest, Central Java and observed their behaviour. We investigated the gum-producing trees that were utilized by the slow lorises by tapping the exudates and examining their nutritional and PSM contents. We found that exudates are the predominant food source for the Javan slow loris in this lowland forest, and that their nutritional contents are similar to those of exudates consumed by lorises in anthropogenically disturbed areas. Significant differences in polysaccharide and flavonoid contents were found between consumed and unconsumed exudates. Knowledge of the diet of the Javan slow loris is crucial to its conservation, and our findings confirm the importance of exudates in its diet. We also highlight the need to preserve natural slow loris habitat, and to manage the diets of these species in captivity. The results of this study indicate that plant exudates should constitute a significant portion of the diet of captive slow lorises, and that the presence of exudate-producing trees is vital in areas into which slow lorises are to be translocated.

Slow loris (Nycticebus borneanus) consumption by a wild Bornean orangutan (Pongo pygmaeus wurmbii).

Vertebrate predation and consumption by wild Bornean orangutans (Pongo pygmaeus spp.) is rare. In contrast to recorded observations of slow loris consumption by Sumatran orangutans (Pongo abelii), no cases of this have been previously published for Bornean orangutans in the wild. In 2017, we observed the capture and consumption of a slow loris (Nycticebus borneanus) by an adult unflanged male Bornean orangutan at Tuanan Orangutan Research Station, which is located in the Kapuas region of Central Kalimantan. The unflanged male was together with an adult female and her 3.5-year-old offspring throughout the event. However, despite the mother and her offspring watching the male closely and occasionally begging while he consumed the loris, he resisted all food-taking attempts. This study reports, to the best of our knowledge, the first documented case of slow loris predation and consumption by a Bornean orangutan, and thus provides an important data point for understanding primate predation on other primate species.

Bioacoustics as a tool to monitor the estrus cycle in a female slow loris (Nycticebus sp.).

Evidence-based husbandry leading to increased reproductive success and strengthening of ex situ populations of slow lorises (Nycticebus spp.) living in zoos is highly important. Better fulfillment of their social needs is one of the main priorities in achieving these objectives. We performed 21-month long acoustic monitoring of a zoo-kept female slow loris (Nycticebus sp.) housed either singly or with one of two males to examine whether her estrus cycle potentially could be detected based on her vocal activity. We found a regular cycle of remarkably increased whistle production that lasted approximately 31.2 days in a nocturnal exhibit and approximately 39 days in an off-show room. The regular cycle of increased vocal activity corresponded to a previously described estrus cycle of slow lorises and was observable in the presence of both males as well as when the female was housed singly. Additionally, vaginal smears collected from the female close to the peak period of her vocal activity showed signs of proestrus and estrus. The acoustic properties of the whistles, specifically that they did not overlap with or were loud enough to exceed background noise commonly occurring in zoos, made them perfect candidates for analyses involving automatic processing of a large number of recordings. We conclude that bioacoustics represents a promising, completely noninvasive and relatively easily applicable tool that allows detection and anticipation of the estrus cycle in some females, thus improving the social management of slow lorises living in zoos.

Variation in predicted COVID-19 risk among lemurs and lorises.

The novel coronavirus SARS-CoV-2, which in humans leads to the disease COVID-19, has caused global disruption and more than 2 million fatalities since it first emerged in late 2019. As we write, infection rates are at their highest point globally and are rising extremely rapidly in some areas due to more infectious variants. The primary target of SARS-CoV-2 is the cellular receptor angiotensin-converting enzyme-2 (ACE2). Recent sequence analyses of the ACE2 gene predict that many nonhuman primates are also likely to be highly susceptible to infection. However, the anticipated risk is not equal across the Order. Furthermore, some taxonomic groups show high ACE2 amino acid conservation, while others exhibit high variability at this locus. As an example of the latter, analyses of strepsirrhine primate ACE2 sequences to date indicate large variation among lemurs and lorises compared to other primate clades despite low sampling effort. Here, we report ACE2 gene and protein sequences for 71 individual strepsirrhines, spanning 51 species and 19 genera. Our study reinforces previous results while finding additional variability in other strepsirrhine species, and suggests several clades of lemurs have high potential susceptibility to SARS-CoV-2 infection. Troublingly, some species, including the rare and endangered aye-aye (Daubentonia madagascariensis), as well as those in the genera Avahi and Propithecus, may be at high risk. Given that lemurs are endemic to Madagascar and among the primates at highest risk of extinction globally, further understanding of the potential threat of COVID-19 to their health should be a conservation priority. All feasible actions should be taken to limit their exposure to SARS-CoV-2.

Risky Business: The Function of Play in a Venomous Mammal-The Javan Slow Loris (Nycticebus javanicus).

Immature mammals require opportunities to develop skills that will affect their competitive abilities and reproductive success as adults. One way these benefits may be achieved is through play behavior. While skills in developing use of tusks, antlers, and other weapons mammals have been linked to play, play in venomous animals has rarely been studied. Javan slow lorises (Nycticebus javanicus) use venom to aid in intraspecific competition, yet whether individuals use any behavioral mechanisms to develop the ability to use venom remains unclear. From April 2012 to December 2020, we recorded 663 play events and studied the factors influencing the frequency of play and the postures used during play in wild Javan slow lorises. Regardless of the presence of siblings, two thirds of play partners of young slow lorises were older and more experienced adults. Young lorises engaged in riskier behaviors during play, including using more strenuous postures and playing more in riskier conditions with increased rain and moonlight. We found that play patterns in immature lorises bear resemblance to venom postures used by adults. We suggest that play functions to train immature lorises to deal with future unexpected events, such as random attacks, as seen in other mammalian taxa with weapons. Given the importance of venom use for highly territorial slow lorises throughout their adult lives and the similarities between venom and play postures, we cannot rule out the possibility that play also prepares animals for future venomous fights. We provide here a baseline for the further exploration of the development of this unique behavior in one of the few venomous mammals.

Severe Anaphylactic Shock Following a Slow Loris Bite in a Patient with Cat Allergy.

The slow loris monkey is one of the few venomous mammals. Its venom repels predators and can cause anaphylactic shock and even death in humans. The venom protein has been evaluated and has high sequence similarity to cat allergen; however, no studies involving subjects with cat allergy and who have been exposed to slow loris venom have been reported. We herein report the first case of severe anaphylactic shock following a slow loris bite in a patient with cat allergy.

Social relationships among captive male pygmy slow lorises (Nycticebus pygmaeus): Is forming male same-sex pairs a feasible management strategy?

Little is known about the social behavior of pygmy slow lorises, in particular, the social relationships of same-sex individuals have rarely been investigated. The Slow Loris Conservation Center was built at the Japan Monkey Center to enhance the welfare of confiscated slow lorises, promote their conservation, improve public education, and perform scientific research on the species. In the course of improving housing conditions, several same-sex pairs of pygmy slow lorises were formed. We monitored their behaviors and fecal glucocorticoid metabolite (FGM) levels to understand whether male same-sex pairings could be a feasible management strategy. The subjects were 10 male and 6 female lorises for comparison, all of whom were over 5 years old. We successfully formed five pairs of male lorises after eight formation attempts. Male pairs initially showed some aggressive behaviors; however, the rate decreased approximately 10 days after introduction. All of the male pairs eventually exhibited extensive affiliative social behaviors, including allogrooming and social play, during the dark (active) phase, and sleep site sharing during the light (inactive) phase. The rate of sleep site sharing during the light phase was higher than expected, suggesting that the pairs preferred to stay near each other. There was no evidence of increased stress after a long period of male-male social housing. Female same-sex pairs and male-female pairs demonstrated a high level of affiliative behaviors right after the introduction. These results highlight the flexibility and high sociability of this species and indicate that such same-sex pairings are a feasible option for their social management.

Detection of a Larva of Armillifer armillatus in a Potto (Perodicticus potto) from the Republic of the Congo.

We determined the complete sequence of the mitochondrial DNA (mtDNA) of a parasite discovered between the subcutaneous tissue and the peritoneum of an African nocturnal non-human primate (NHP). The parasite and host sequences were obtained by a combination of Sanger sequencing and nanopore MinION techniques. Analyses of mtDNA gene arrangements and sequences unambiguously showed that the parasite investigated was the pentastomid Armillifer armillatus, also commonly named the tongue worm. The full-length mitochondrial genome of A. armillatus, measuring 16,706 bp in length, contains 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes, an arrangement identical to that of previously described pentastomid mitochondrial genomes. We describe here the second full mitochondrial genome of A. armillatus to date. To identify the NHP host, maximum likelihood phylogenetic analyses of a 441-bp fragment on the 12S rDNA gene and of a 1,140-bp fragment of the mitochondrial cytochrome b strongly support clustering with the African lorisid Perodicticus potto, a species that has rarely been reported as an intermediate host of this parasite.

Slow lorises use venom as a weapon in intraspecific competition.

Animals have evolved an array of spectacular weapons, including antlers, forceps, proboscises, stingers, tusks and horns [1]. Weapons can be present in males and females of species needing to defend critical limiting resources, including food (rhinoceros beetles, Trypoxylus) and territories (fang blennies, Meiacanthus) [1-3]. Chemicals, including sprays, ointments and injected venoms, are another defence system used by animals. As with morphological weapons, venom can serve multiple purposes, including to facilitate feeding, in predation, and in defence when attacked [4]. Although rare, several taxa use venom for agonistic intraspecific competition (e.g. ghost shrimp, Caprella spp.; sea anemones, Actinia equina; cone snails, Conidae; male platypus, Ornithorhynchus anatinus) [4-6]. Another group of venomous mammals are the nocturnal slow lorises (Nycticebus) [7]. Slow loris bites often result in dramatic diagnostic wounds characterised by necrotic gashes to the head and extremities. Although these bites are the major cause of death of lorises in captivity, the function of this aggressive behaviour has never been studied in the wild [7]. Here, through an 8-year study of wounding patterns, territorial behaviour, and agonistic encounters of a wild population of Javan slow lorises (Nycticebus javanicus), we provide strong evidence that venom is used differentially by both sexes to defend territories and mates. VIDEO ABSTRACT.

Variation in Gut Microbiota of Captive Bengal Slow Lorises.

Gastrointestinal microbiome plays an important role in animal metabolism, immune system and pathology associated with health and disease. Many wild slow lorises were confiscated from illegal trade into captivities and experienced a range of changes in living environment and diet. Microbiome analysis contributes to improving captive management by identifying the alteration in their gastrointestinal microbial communities and aiding in determining the factors affecting the health of captive slow lorises. The fecal samples of eighteen Bengal slow lorises (Nycticebus bengalensis) were used to compare gut microbiota from four rescue centers located in Dehong, Gejiu, Nanning and Puer cities of China. The results showed a significant site-dependent difference in microbial community diversity. Similar to other Lorisinae species, the Phyla including Bacteroidetes, Firmicutes and Proteobacteria dominated their gut microbiome composition. The Gejiu group exhibited a higher overall diversity and the unique OTUs, which is resulted from long-term isolated husbandry and heavy human disturbances. The scarcity of gums in the captive diet was likely to cause a lower abundance of Prevotella associated with soluble fiber degradation. The variation of intestinal microbiota in different environments highlights the necessity to improve feed preparation and husbandry management for the captive Bengal slow lorises.