Captive Conditions Research Articles

Linking Gut Microbiota and Stereotypic Behavior of Endangered Species Under Ex Situ Conservation: First Evidence from Sun Bears

Integrative conservation research on animal behavior and nutritional health can contribute to the ex situ conservation of endangered species. Stereotypic behavior, a repetitive behavior without practical function, is associated with animal welfare in its manner and frequency for captive animals. Exploring the potential relationship between stereotypic behavior and internal factors, such as intestinal flora, could improve ex situ conservation, especially for endangered species. In this study, we analyzed the typical behavior characteristics of the endangered sun bears (Helarctos malayanus) under captive conditions based on the behavior sampling method. The seasonal and annual changes in the intestinal flora of H. malayanus in captivity were studied by 16S rDNA high-throughput sequencing technology based on non-invasive fecal sample collection. This study provides the first evidence of a potential association between the gut microbiota and stereotypic behavior characteristics of captive H. malayanus. The results can significantly improve our understanding of the stereotypical behavior of H. malayanus in captivity and contribute to the captive breeding and conservation efforts of this endangered species.

Comparative Efficacy of Synthetic Hormones, Wova-FH and Ovatide on Breeding Performance of a <i>Cypirinus carpio</i> Var. communis in the Captive Conditions of Kashmir

This study assessed the efficacy of two GnRH-based synthetic hormones, Ovatide and Wova-FH, in the induced breeding of common carp (Cyprinus carpio) under the environmental conditions of Kashmir. A Completely Randomized Design (CRD) with three treatments for each hormone and a control group, performed in triplicates, was employed. The latency period varied significantly, with Ovatide showing superior performance. The shortest latency period (38±0.38 hours) was recorded at the highest dosage of Ovatide (0.7 mL/kg), compared to 44±0.57 hours for Wova-FH (0.5 mL/kg) and 55.5±0.5 hours for the control. Ovatide also achieved the highest ovulation rate (88.8%), significantly outperforming Wova-FH (55.5%) and the control (22.2%). Fertilization rates were significantly higher in Ovatide-treated groups, ranging from 85.25%±0.98 to 86.20%±1.12, compared to 83.42%±0.69 to 84.04%±1.15 in Wova-FH groups. However, hatching rates ranged from 67.80%±0.66 to 71.08%±1.37 across all treatments with no significant differences (p>0.05) between hormone-treated and the control groups, indicating that hatching success is independent of hormone type and dosage. This study provides evidence supporting the use of Ovatide as a more effective inducing agent for carp breeding in Kashmir for sustainable aquaculture development in the region.

First documentation of a jaguar (Panthera onca) with otitis caused by Otobius megnini (Dugés 1883).

Otobius megnini (spinose ear tick) is a cosmopolitan soft tick that parasitizes domestic and wild mammals, as well as humans. The larval and nymphal stages are common parasites that feed on blood inside the canal ears of hosts, while adults are nonfeeding and live off the host. Different nymphal stages of O. megnini were collected from a jaguar (Panthera onca) suffering from otitis in captive conditions from Guerrero, Mexico. This is the first documentation worldwide of O. megnini in a jaguar with otitis. The presence of this tick species represents a risk of transmission to animals and humans exposed to the nymphal stages of the tick.

Changes in Blood Quality and Metabolites of Tachypleus tridentatus Under Captive Breeding Conditions

ABSTRACTTo reveal the effects of captive breeding on the physiology and metabolism of Tachypleus tridentatus, 90 T. tridentatus juveniles were selected, and blood samples were collected from each four times during a 90‐day experiment. The blood quality was analysed by measuring Cu content. The results showed that, on Days 0, 30, 60 and 90, the Cu content in the blood of male juvenile T. tridentatus was 37.15, 22.62, 10.15 and 16.63 mg/L, respectively, with Days 30, 60 and 90 being 39.10%, 72.69% and 55.23% lower than Day 0. The Cu content in the blood of female T. tridentatus on Days 0, 30, 60 and 90 was 39.89, 20.27, 7.33 and 7.53 mg/L, respectively, with decreases of 45.44%, 80.26% and 81.11% on Days 30, 60 and 90 compared with Day 0. This indicated that the blood quality of male and female T. tridentatus decreased under captive breeding conditions. To measure metabolites, three male and three female T. tridentatus were selected and cultured under captive breeding conditions, and blood samples were collected on Days 0 and 30 and analysed using nontargeted metabolomics. Thirteen differentially expressed metabolites were identified, among which six significantly increased and seven significantly decreased. Among metabolic pathways, the sphingolipid metabolic pathways were notably affected. Changes in significant metabolites and metabolic pathways revealed nutritional deficiencies in protein, fat and vitamins. Insufficient nutrient supply was an important reason for the decline in blood quality of T. tridentatus under captive breeding conditions. In addition, four significantly different metabolites, namely, sphingosine, heptadecasphingosine, D‐erythro‐imidazolyl glycerophosphate and stearic acid, were selected as future target metabolites to analyse the nutritional demand of T. tridentatus under captive breeding conditions.

Gene expression comparisons between captive and wild shrew brains reveal captivity effects.

Compared with their free-ranging counterparts, wild animals in captivity experience different conditions with lasting physiological and behavioural effects. Although shifts in gene expression are expected to occur upstream of these phenotypes, we found no previous gene expression comparisons of captive versus free-ranging mammals. We assessed gene expression profiles of three brain regions (cortex, olfactory bulb and hippocampus) of wild shrews (Sorex araneus) compared with shrews kept in captivity for two months and undertook sample dropout to examine robustness given limited sample sizes. Consistent with captivity effects, we found hundreds of differentially expressed genes in all three brain regions, 104 overlapping across all three, that enriched pathways associated with neurodegenerative disease, oxidative phosphorylation and genes encoding ribosomal proteins. In the shrew, transcriptomic changes detected under captivity resemble responses in several human pathologies, including major depressive disorder and neurodegeneration. While interpretations of individual genes are tempered by small sample sizes, we propose captivity influences brain gene expression and function and can confound analyses of natural processes in wild individuals under captive conditions.

A review of the reproduction and rearing of clownfish, Amphiprion clarkii, in captivity

Clownfishes are very popular among ornamental fish keepers due to their aesthetic appeal and easy adaptability to captive conditions. The captive breeding of these fish not only meets the market demand but also prevents the destruction of their natural habitats during fishing. In Iran, Amphiprion clarkii has been successfully bred and reared in the Bandar Lengeh mollusks research center. The broodfish were fed twice a day in the morning and the afternoon at 5% of body weight. The pot was used as a shelter for broodfish spawning in the aquarium. One indication of impending spawning was the male and female broodfish cleaning inside the shelter. In this species, the number of eggs per spawning was 300-400. The eggs were sticky and protected by their parents during the incubation period. At 28 ◦C, the eggs were hatched after six days. During the first two weeks after hatching, rotifer and Artemia nauplii were exclusively utilized to feed the larvae. The weaning process started 15 days after hatching (DAH), and on 25 DAH, all the larvae completely shifted to the microparticulate diet. To improve the color of farmed fishes, the formulated feed prepared for the larvae and juveniles was supplemented with 100 ppm and 200 ppm astaxanthin, respectively. During 2-4 months, the juveniles reached the size of 3-4 cm and were ready to be sold in the market. The survival rate during this period was more than 50%.

Comparative Metagenomic Analysis of the Gut Microbiota of Captive Pangolins: A Case Study of Two Species.

Pangolins, one of the most trafficked mammals, face significant health challenges in captivity, including digestive disorders and immune dysfunctions. These issues are closely linked to alterations in their gut microbiota, which play vital roles in the host metabolism, immunity, and overall health. This study investigated the differences in the gut microbiota composition and function between two pangolin species, Chinese pangolins (Manis pentadactyla) and Malayan pangolins (Manis javanica), under identical captive conditions to better understand their ecological adaptability and health implications. Using metagenomic sequencing, fecal samples from eight adult captive pangolins were analyzed, including four male Malayan pangolins and three male and one female Chinese pangolins. Comparative analyses of the alpha and beta diversities, microbial community structure, and functional profiles were performed. Both species harbored gut microbiota dominated by Firmicutes, Bacteroidetes, and Proteobacteria. However, the Chinese pangolins exhibited higher microbial diversity (Shannon index, p = 0.042; Simpson index, p = 0.037) and lower relative abundance of Proteobacteria compared with the Malayan pangolins. A functional analysis revealed significant differences in the metabolic pathways, where the Chinese pangolins demonstrated a higher potential for fiber degradation, whereas the Malayan pangolins exhibited elevated levels of antibiotic resistance genes and pathogenic taxa, such as Escherichia coli. These findings suggest that captivity duration and environmental stress likely contribute to the observed differences, with the Malayan pangolins experiencing greater dysbiosis due to longer captivity periods. This study provides valuable insights into the role of gut microbiota in pangolin health and offers a foundation for improving conservation strategies and captive care protocols.

Label-free quantitative proteomic analysis reveals the characteristics of ovarian development from stage II to III in Chinese sturgeon (Acipenser sinensis)

Chinese sturgeon (Acipenser sinensis) is an endangered anadromous and rare fish. The ovary development from stage II to III is being challenged by captive conditions, which seriously hinders the artificial reproduction of Chinese sturgeon. A comparative proteomic analysis on the ovaries at stage II and stage III of Chinese sturgeon was conducted in this study using the label-free quantitative method to uncover the intricate physiological processes. The findings revealed 200 up-regulated differentially expressed proteins (DEPs) and 150 down-regulated DEPs in the ovary at stage III compared with stage II, and 11 DEPs (including UCHL1, VTG, CTSD, and ZP, etc.) involved in the vitellogenesis and oocyte growth. Moreover, the up-regulated DEPs exhibited significant enrichment in the pathways linked to protein synthesis (ribosome, protein processing in the endoplasmic), metabolism and energy production (valine, leucine and isoleucine degradation, TCA cycle, oxidative phosphorylation, and fatty acid degradation), suggesting more active protein processing and energy metabolism at stage III. Meanwhile, APOB was down-regulated while VTG was up-regulated in stage III ovary, indicating the uptake of yolk protein and lipid through VTG at this stage. The parallel reaction monitoring (PRM) quantification of 16 DEPs solidly validated the outcomes of label-free analysis. This study provided powerful information for understanding the physiological processes of ovarian development in Chinese sturgeon, and potential biomarkers in predicting the vitellogenic stage.

Revisiting Linear Enamel Hypoplasia in Cayo Santiago Rhesus Macaques (Macaca mulatta): How a Stress Marker Relates to Environment and Maternal Lineage in a Rare Rhesus Colony With Known Life History.

Linear enamel hypoplasias (LEHs) are development defects appearing as lines or grooves on enamel surfaces. Forming when physiological stressors disrupt developing teeth, LEHs provide retrospective insight into stress experienced in early development. Here, LEHs in Cayo Santiago rhesus macaques (Macaca mulatta) were observed with respect to decade of birth, whether an individual was transferred from the free-ranging colony to the captive facility during probable crown formation periods, and matriline of birth. It was hypothesized that later decades would exhibit higher prevalence than earlier decades as climatic conditions in Puerto Rico worsened over time. Transfer was expected to affect LEH formation because the process of transfer, and subsequent restriction to captivity, is thought to be stressful. Matriline membership was hypothesized to relate to LEH formation because there is some evidence of a genetic influence on susceptibility to form LEH and because offspring of matrilines of different dominance ranks are known to experience different levels of aggression. Lower third premolars with minimal enamel surface wear were scored for LEH using a digital microscope, while a follow-up analysis of the two matrilines with the most extreme differences in LEH frequency was conducted using enamel surface profiles. Results were: (1) individuals born during the 1990s had significantly greater LEH prevalence than those born in the 1960s, (2) transferred individuals exhibited weak evidence of greater LEH prevalence than nontransferred comparison groups, and (3) matrilines did not differ in LEH expression in the initial or follow-up analysis. Although sample sizes were small for some comparisons, these results suggest that not all decades saw an equal prevalence of LEH, that there might be a small effect of transfer from free-ranging to captive conditions on LEH prevalence that is difficult to detect, and that the matriline into which an individual is born is not related to LEH expression.

An exploration of the postural, location- and social contact- related sub-characteristics of inactive but awake behaviour as a depression-like indicator in mice

Inactive behaviour is essential to life. However, specific forms of inactivity may be indicative of compromised welfare in certain captive conditions. Inactive but awake behaviour (IBA - spontaneous, motionless awake behaviour without interacting with the surroundings) has been documented in some species and may be associated with poor welfare and negatively valenced affective states. In our previous work in laboratory mice, we have identified environmental risk factors (non-enriched housing) and curative factors (antidepressant drug Venlafaxine) for IBA and we hypothesise that greater levels of IBA may represent a depression-like state in this species. Here we aimed to identify which specific sub-characteristics of IBA would show construct validity as a depression-like state by exploring the posture (i.e. lying, curled lying or sitting), social contact position (i.e. in physical contact with a cage mate or not) and location of mice while performing the behaviour during two experiments (respectively investigating the aetiology and the curative factors of IBA). In both experiments we expected that more IBA would be displayed in standard (non-enriched) laboratory cages, compared with large highly-enriched cages and that a move from a highly-enriched to a non-enriched cage would increase IBA, while the opposite treatment would result in a decrease. In our second experiment (curative factors investigation), we predicted that less IBA would be displayed by mice that voluntarily ingested an antidepressant (Venlafaxine) versus a placebo. Because we could not control the number of instances of each IBA sub-characteristic we measured and we had no a priori predictions about which IBA sub-characteristics would match our general IBA treatment predictions, we compared the effect size and the direction of the effect between our treatment groups to explore which of the sub-characteristics matched our general IBA predictions. Overall, we found little variation in the location IBA was performed, with the majority being seen in the nest. Across treatment comparisons in both experiments, overall, the largest effect sizes were measured for IBA performed when in contact with the cage mate and performed when lying and both characteristics generally matched the direction of our treatment-related predictions. We suggest that future work should perform more detailed analyses of the specific characteristics of IBA by identifying behavioural sequences and the co-occurrence of the sub-characteristics to obtain a more complete picture of IBA as a depression-like indicator.

Assessment of Gut Microbiome Variations in the Mother and Twin Infant of Captive White-handed Gibbons (Hylobates lar) Reveals the Presence of Beneficial and Pathogenic Bacteria

The white-handed gibbon (Hylobates lar) is one of the three Hylobatidae species found in the Peninsular Malaysia region. Studies on primate gut microbiota have yet to be conducted in Malaysian Hylobatidae, but previous studies have covered Cercopithecidae. Knowledge of the gut microbiota of endangered captive Malaysian Hylobatidae primates is important for health assessment and conservation management. Thus, the main objective of this study was to determine the gut microbiota profile of captive white-handed gibbons using the metabarcode 16S rRNA gene. Two H. lar fecal samples collected from the mother and twin infant at Zoo Melaka were used for DNA extraction. Next-generation sequencing (NGS) of the 16S rRNA gene was performed. The NGS data were analyzed on the basis of amplicon sequence variation. The gut microbiota of H. lar was dominated by Firmicutes and Bacteroidota because of their important roles in fermentation and nutrient assimilation from plant-based food sources. Predominance of Prevotella in the gut microbiota of H. lar indicates that the captivity condition causes the gut microbiota of gibbons to resemble that of humans. Treponema, a pathogenic bacterium, was also detected in the mother and twin infant. Variation in the bacterial community profile between the mother and the infant indicated differences in dietary adaptations and physiological state. This study provides an overview of gibbon health levels through gut microbiome screening and can be used when considering Malaysian primate health welfare and captive management.

Ontogeny and Growth of Early Life Stages of Barred Spiny Eel Macrognathus pancalus (Hamilton, 1822)

Background: The objective of the study was to examine the growth and development of M. pancalus larvae in captive conditions, including pigmentation patterns, yolk and oil globule utilization, growth rates and metamorphosis, as well as to identify suitable live food for larviculture. Methods: The larvae, produced through induced breeding, were kept unfed until the yolk-sac absorption and then fed with freshwater rotifer, mixed zooplankton and Tubifex worms at different stages of development. The larvae were reared in indoor glass tanks and outdoor reinforced plastic tanks to document their morphological and chronological development. Result: The findings showed that the larvae exhibited typical characteristics of eel. Notably, dentition was observed before yolk resorption, indicating the highly predatory nature of the larvae. The bands of melanophores, which were prominent at the beginning, disappeared between 5-7 days post-hatch. Additionally, the study identified distinct features of spiny eels, such as a trunk-like rostral projection at 14 days post-hatch and erectile dorsal spines at 21 days post-hatch. The growth pattern, morphological changes and adaptation to benthic burrowing habits indicated that the larvae metamorphosed into the fry stage between 28-45 days post-hatch. These results provide valuable insights into the ontogenetic development and rearing of M. pancalus and can be used to support future aquaculture and conservation programs.

Paternal behavior in captive fat-tailed dwarf lemurs (Cheirogaleus medius) is preserved under socially relevant conditions.

Fat-tailed dwarf lemurs (Cheirogaleus medius), primates endemic to Madagascar, are obligate hibernators that form stable, lifelong pairs in the wild. Given the temporal constraints imposed by seasonal hibernation, infant dwarf lemurs must grow, develop, and wean within the first two months of life. Maternal as well as paternal infant care, observed in the wild, has been deemed critical for infant survival. Given the importance of fathers' involvement in early infant care, we expect this behavior to persist even under captive conditions. At the Duke Lemur Center, in Durham NC, we observed two families of fat-tailed dwarf lemurs and focused on the behavior of adult males within the first two months of the infants' lives. We report evidence of paternal involvement, including babysitting, co-feeding, grooming, accompanying, and leading infants, consistent with observations from the wild. As expected, paternal babysitting decreased as infants gained independence, while co-feeding increased. Supplemental anecdotes, video recorded by observers, also highlight clear cases of involvement by both parents, and even older siblings, in safeguarding and socializing new infants. We argue that maintaining captive fat-tailed dwarf lemur populations under socially and ecologically relevant conditions facilitates the full expression of physiological and behavioral repertoires. Most importantly, it also allows dwarf lemurs to realize their species' potential and become robust proxies of their wild kin.

6DoF CFD Analysis for High-Speed Small Craft in Free Running Conditions

ABSTRACT CFD simulations of a high-speed small craft are performed with 6DoF motions. The hull form and propulsor are scaled to match a deep V fishing boat (DVFB). The on water experimental data of the DVFB was used for qualitative validation. Many captive and free running conditions are considered including some most critical conditions, such as 2DoF captive motion, free running self-propulsion, turning circles in calm water and waves, acceleration, and avoidance line tests. The present work is the first known CFD study for the free running of high-speed small craft with 6DoF motions and is exploratory in nature. The accuracy and performance of the gear case and propeller models are evaluated with the issues identified. Other issues are also discussed including the optimum grid sizes, submerged depth of the gear case, and instabilities. All of these can be provided as recommendations for the future research improvements.

Influence of humic acids on growth performance, bravery, stress resistance, antioxidant activity, and immune gene expression in male Siamese fighting fish (Betta splendens)

The current study investigated the effects of a humic acid supplement on the growth performance, antioxidant enzyme activity, immune-related genes, behavior and endocrinology of male Betta splendens fish. Fish species that are naturally exposed to high levels of humic substances in their environment are likely to perform better under captive conditions when given these substances. In this study, fish were fed a diet containing 0, 0.5 %, 1 %, and 1.5 % humic acid for six weeks. The results showed no significant differences in growth and feeding parameters between treatments (p > 0.05). The fish with a diet of 1.5 % humic acid showed more aggressive behavior in the mirror test than the control group (p < 0.05). In contrast, the fish fed a diet containing 1 % and 1.5 % humic acid showed a higher level of activity in the test with new objects than the control group (p < 0.05). The testosterone levels after aggression were significantly higher in the fish fed diets containing 1 % and 1.5 % humic acid than in the control group (p < 0.05). In addition, the humic acid-treated fish showed lower oxidative stress and cortisol production in common aquaculture stressors than the control (p < 0.05). Gene expression analysis showed upregulation of immune-related genes, including β-defensin 1, c-type lysozyme, interleukin-1β, and tumor necrosis factor-α, in response to humic acid supplementation compared to control (p < 0.05). Overall, the results of this study indicate that a diet containing 1 % humic acid has a positive effect on the physiology, immunology, and behavior of male B. splendens.

Variation on gut microbiota diversity of endangered red pandas (Ailurus fulgens) living in captivity acrosss geographical latitudes.

The gut microbiome plays important roles in metabolic and immune system related to the health of host. This study applied non-invasive sampling and 16S rDNA high-throughput sequencing to study the gut microbiota structure of red pandas (Ailurus fulgens) for the first time under different geographical latitudes in captivity. The results showed that the two predominant phyla Firmicutes (59.30%) and Proteobacteria (38.58%) constituted 97.88% of the total microbiota in all the fecal samples from north group (red pandas from Tianjin Zoo and Jinan Zoo) and south group (red pandas from Nanjing Hongshan Forest Zoo). The relative abundance of Cyanobacteria in north group was significantly higher than that in south group. At the genus level, Escherichia-Shigella (24.82%) and Clostridium_sensu_stricto_1 (23.00%) were common dominant genera. The relative abundance of norank_f__norank_o__Chloroplast, Terrisporobacter and Anaeroplasma from south group was significantly higher than that of north group. Alpha and Beta analysis consistently showed significant differences between north group and south group, however, the main functions of intestinal microbiota were basically the same, which play an important role in metabolic pathways, biosynthesis of secondary metabolites, microbial metabolism in different environments, and amino acid biosynthesis. The variations in gut microbiota between the northern and southern populations of the same species, both kept in captivity, which are primarily driven by significant differences in climate and diet. These findings provide a deeper understanding of the gut microbiota in red pandas and have important implications for their conservation, particularly in optimizing diet and environmental conditions in captivity.

Validation of the Lead Care II System in Cape vultures (Gyps coprotheres) in comparison to ICP-MS using pure standards

Lead toxicosis remains a concern in raptors, especially following feeding on carcasses sourced from hunting. Rapid diagnosis of lead exposure and easy field monitoring is desirable. The LeadCareII analytical system, validated for rapid diagnoses of lead toxicity in humans, has been described as a useful evaluation system in various species. For this study we attempt to validate the LeadCareII system in the Cape Vulture (CV) (Gyps coprotheres). Blood samples from CV housed under captive conditions and low background lead exposure, were pooled and spiked with known concentrations of a lead standard (0–60 µg/dL). Samples were analyzed by the LeadCareII system and by ICP-MS. The final results showed that despite good linearity the LeadCareII system underestimated lead concentrations by up to 50 %. While the results can be corrected by the derived equation, this is not supported due to the large underestimations evident. The reason for the underestimation is presently unknown.

Behavioral Diversity Among Odonata Larvae Increases in Water with Greater Turbidity Under Captivity Conditions.

Various factors, including environmental variables, influence the behavior of aquatic insects. However, our understanding of insect behavior and their relationships with these variables remains limited. One important variable is water turbidity, which may be exacerbated by soil erosion, directly impacting visibility in the water and potentially affecting the organism's behaviors. In this study, we investigated larval behavior across seven Odonata species under controlled conditions, examining variations in behavioral diversity (frequency and type) associated with sex and three levels of water turbidity. Our findings revealed that heightened water turbidity correlated with increased behavior frequency, possibly attributable to predator avoidance in darker, seemingly safer habitats. Furthermore, behavior diversity differed between sexes, being higher for males in certain categories and for females in others. Anisoptera species predominantly displayed behaviors like resting, eating, and prey capture, whereas Zygoptera larvae were often observed perching and walking, possibly indicative of distinct predator response strategies. Behaviors shared by Anisoptera larvae could be associated with similar responses to predators and capture of prey. Our study found an increased frequency of behaviors when the larvae are in water with higher turbidity. Behavior frequency disparities between the sexes were observed across various behaviors, likely influenced by species-specific activity levels and individual behavioral plasticity in response to environmental cues. Overall, individuals exhibited heightened behavioral activity in environments with elevated turbidity, potentially reflecting a perceived lower risk environment.

The impact of host development and density stress on the diversity of microbial communities in the gut and its surrounding environment of the Chinese alligator

AbstractThe Chinese alligator (Alligator sinensis) is currently an endangered species due to a combination of factors, including climate change, anthropogenic activities, and habitat fragmentation. Captivity plays a crucial role in mitigating the decline of the Chinese alligator population. Currently, there is a lack of clarity regarding the influence of host development and captive conditions on the gut microbiota of Chinese alligators. The aim of the study was to investigate the gut bacterial communities of Chinese alligators and their surrounding environmental bacterial communities using 16S rRNA sequencing. The primary gut flora of Chinese alligators consists of Proteobacteria, Bacteroidetes, and Firmicutes. Proteobacteria is the most abundant and efficient settler in the gut, water, and sediment. PCoA and Adonis test revealed significant differences in bacterial communities across these habitats. Venn analysis revealed overlap in OTUs among the gut, water, and sediment, varying with growth stage and density stress. Different growth stages of Chinese alligator guts harbor distinct pathogenic bacteria, requiring attention. Density stress leads to an increase in pathogenic bacteria, a decrease in gut absorption efficiency. PICRUst2 predicts more abundant metabolic pathways related to gut function during high‐density stress, possibly linked to Roseburia. SourceTracker Analysis indicated that water bacteria have a greater impact on Chinese alligator gut bacteria than sediment, and density stress significantly affects the contribution of environmental microorganisms to the gut microbes of Chinese alligator. BugBase analysis identified water body microbes as the main source of “potentially pathogenic” phenotypes in the gut microbiota. RDA analysis found dissolved oxygen (DO) in water to be the most significant factor influencing water microorganisms, positively correlated with certain pathogenic strains. These findings enhance our understanding of the significance of microbial communities in the gut and surrounding aquatic environment of the Chinese alligator. Furthermore, they provide theoretical support for environmental regulation, disease control, and healthy breeding.

Prevalence and Risk Factors of Bone and Dental Lesions in Neotropical Deer.

Bone and dental lesions have been documented in various deer species globally, affecting the efficiency of ingestion and digestion, consequently influencing their general health and leading to a decline in survival and reproductive performance. The present study aimed to characterize bone and dental lesions in the dry skulls of individual deer, estimate the prevalence of these lesions, and assess potential risk factors associated with the development of bone and dental alterations. This study assessed bone and dental lesions in 180 dry skulls of eleven neotropical deer species, originating from both captivity and wildlife conditions, through direct visual inspection. A high prevalence of bone and dental lesions was observed in all analyzed species. Dental calculus was the most common alteration (96.7%), followed by dental wear (71.1%). Animal age positively correlated with most bone and dental alterations, indicating that older animals showed more lesions. Additionally, the prevalence of these alterations was similar between sexes. Moreover, all lesions were more common in captive-bred animals, likely attributed to their older age and a less diverse diet. Blastocerus dichotomus and Mazama americana were most affected by bone resorption and dental trauma and had the highest dental calculus prevalence, along with Subulo gouazoubira and Passalites nemorivagus. All eleven species evaluated in the present study were susceptible to the occurrence of bone and dental lesions. Therefore, monitoring oral health and diet in captivity are fundamental practices for the conservation of these species.