Natural reproductive performance is associated with captive management in adult male giant pandas

Abnormal expression of natural mating behaviour of captive adult giant pandas is related to physiological stress

During ex situ conservation, the adaptability of giant pandas to environmental changes is greatly challenged. The issue of natural reproduction in captive giant pandas remains unresolved both domestically and internationally. It hypothesized that the restricted natural reproductive capacity may be linked to abnormal mating behavior expression due to physiological stress resulting from incompatible pairings in confined environments. To test this hypothesis, we utilized ultra-high performance liquid chromatographytandem quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) to analyse urine metabolites in captive adult giant pandas during their breeding period. Simultaneously, enzyme-linked immunosorbent assay was employed to measure the levels of cortisol and epinephrine in urine, providing insight into the psychological state of captive giant pandas during mate selection by examining all metabolites and related biochemical pathways. This comprehensive approach aims to fully elucidate the physiological mechanisms underlying the decline in natural reproductive capacity. The metabolomics findings indicate that the aberrant expression of natural mating behaviour in captive adult male and female giant pandas may be associated with dysfunction in amino acid metabolic pathways. The activation of these metabolic pathways is linked to psychological stress, such as the tryptophan metabolic pathway and GABAergic synapse pathway. The results of physiological indicators indicate a significant correlation between the expression of natural mating behaviour in captive adult pandas and the hormone urine cortisol, which is associated with physiological stress. These findings indicate that the atypical manifestation of natural mating behaviour in captive adult giant pandas may be associated with physiological stress induced by incompatible pairings within confined environments.

Monitoring the world-oldest zoo-housed male giant panda (Ailuropoda melanoleuca): A case-study on pathway utilization

Habitat use monitoring is necessary for a comprehensive understanding of the biological and psychological requirements of animals under human care, facilitating improved exhibit designs and promoting animal welfare. Current studies focused on the space use of the exhibit while limited studies examined the pathway use of the zoo-housed animals. This study aimed to investigate the habitat use of An An, the world-oldest male giant panda (Ailuropoda melanoleuca) at Ocean Park Hong Kong using a pathway utilization monitoring method. The result showed uneven utilization of pathways favoring the upper area near his den over the lower area which required longer walking in the hilly exhibit. Moreover, the comparisons of walking directions showed a preference for gentle slopes during uphill movement and a favor for steep slopes during downhill movement. Our study also compared the walking distance between uphill and downhill movements and the results showed that An An walked longer distances heading upward than moving downward due to his choice of pathways. Our results are in line with the findings in the wild population, showing a preference for gentle slopes, especially in uphill movement. Our study demonstrated the value of the pathway monitoring technique. Due to its easy and time-effective use, this technique can be incorporated into the care teams' operation, providing valuable information on daily activity (e.g. accessing the walking ability of the aged animals by investigating the pathway use and walking distance) and habitat use. Consequently, the pathway monitoring technique can help improve exhibit designs promoting welfare.

The resistance patterns and molecular characteristics of ESBL/AmpC-producing Escherichia coli from captive panda ecosystem in China

Escherichia coli (E. coli) plays an important ecological role, and is a useful bioindicator to recognize the evolution of resistance in human, animal and environment. Recently, extended-spectrum β-lactamases (ESBL) producing E.coli has posed a threat to public health. Generally, captive healthy giant pandas are not exposed to antibiotics; however, they still acquire antimicrobial resistant bacteria. In order to understand whether there is an exchange of resistance genes within the ecosystems of captive giant pandas, this study explored resistance characteristics of 330 commensal E. coli isolates from feces of giant pandas, the surroundings, and breeders. Isolates from different sources showed similar resistance phenotype, and ESBL/AmpC-producing isolates showed more profound resistance to antibiotics than non-ESBL/AmpC-producing isolates (P<0.05). Furthermore, the occurrence of broad-spectrum β-lactamase related resistance genes and colistin resistance genes was detected, and isolates phylogenetic typing and multilocus sequence typing (MLST) were applied in this study. Seven different β-lactamase resistance genes (blaCTX-M-55, blaCTX-M-15, blaCTX-M-27, blaCTX-M-65, blaTEM-1, blaOXA-1 and blaCMY) and mcr-1 were found in 68 ESBL/AmpC-producing isolates. blaCTX-M-55 (48.53 %) was found the most predominant resistance genes, followed by blaTEM-1 (19.12 %) and blaCTX-M-27 (16.18 %). Nonetheless, blaCTX-M-55 was commonly detected in the isolates from giant pandas (63.16 %), the surroundings (43.48 %), and breeders (33.33 %). However, there were no carbapenemase genes detected in this study. mcr-1 was harbored in only one isolate from giant panda. Forty-five tansconjugants were successfully obtained in the conjugation experiments. The presence of antimicrobial resistance and related resistance genes tested were observed in the transconjugants. The results indicated that 52.63 % of the isolates from giant panda 73.91 % of the isolates from surroundings, and 100 % of the isolates from breeders were phylogroup A. Total of 27 sequence types (ST) were recognized from the isolate by MLST and found that ST48 (19/68; 27.94 %) was the predominant ST type, especially in the isolates from giant pandas and the surroundings. In conclusion, commensal ESBL/AmpC-producing E. coli becomes a reservoir of ESBL resistance genes, which is a potential threaten to health of giant pandas. The interaction between giant pandas, surroundings and breeders contribute to development of resistant phenotypes and genotypes which might transfer across species or the surroundings easily; hence, strict monitoring based on a "One Health" approach is recommended.

Natural mating ability is associated with gut microbiota composition and function in captive male giant pandas

The issue of poor sexual performance of some male giant pandas seriously impairs the growth and the genetic diversity of the captive population, yet there is still no clear understanding of the cause of the loss of this ability and its underlying mechanism. In this study, we analyzed the gut microbiota and its function in 72 fecal samples obtained from 20 captive male giant pandas, with an equal allocation between individuals capable and incapable of natural mating. Additionally, we investigated fecal hormone levels and behavioral differences between the two groups. A correlation analysis was then conducted among these factors to explore the influencing factors of their natural mating ability. The results showed significant differences in the composition of gut microbiota between the two groups of male pandas. The capable group had significantly higher abundance of Clostridium sensu stricto 1 (p adjusted = .0021, GLMM), which was positively correlated with fatty acid degradation and two-component system functions (Spearman, p adjusted < .05). Additionally, the capable group showed higher gene abundance in gut microbiota function including purine and pyrimidine metabolism and galactose metabolism, as well as pathways related to biological processes such as ribosome and homologous recombination (DEseq2, p adjusted < .05). We found no significant differences in fecal cortisol and testosterone levels between the two groups, and no difference was found in their behavior either. Our study provides a theoretical and practical basis for further studying the behavioral degradation mechanisms of giant pandas and other endangered mammal species.

Intestinal acetic acid regulates the synthesis of sex pheromones in captive giant pandas

As a typical solitary animal, adult giant pandas rely on chemical signals (sex pheromones) to transmit reproductive information during oestrous. Although researchers have confirmed that the gut microbiota is related to the emission and reception of sex pheromones, there is no clear correlation between the gut microbes and the synthesis of sex pheromone of giant pandas, that is, which gut microbes and microbial metabolites are participate in the synthesis of giant panda's sex pheromone. As a mirror of gut microbiota, fecal microbiota can reflect the composition of gut microbiota and its interaction with host to some extent. The purpose of this study is to explore how the gut microbes affect the synthesis of sex pheromones in captive giant pandas by combining analysis of the fecal microbiome and metabolomics. The results of correlation and microbial function analysis show that intestinal microorganisms such as Veillonellaceae and Lactobacillilaceae are associated with the synthesis of short chain fatty acid (acetic acid) and volatile ester metabolites, such as 1-butanol, 3-methyl, acetate, acetic acid, hexyl ester and 3-hexen-1-ol, acetate, (Z). In summary, based on this study, we believe that volatile metabolites such as fecal acetate participate in the process of mate preference of captive giant pandas and affect their expression of natural mating behavior. The possible mechanism is that the gut microbes can promote the synthesis of key chemical signaling substances in perianal glands through mediated intermediate fecal metabolites, thus affecting the normal information exchange between giant pandas individuals. The results of this study have greatly enriched our understanding of gut microbes regulating the synthesis of sex pheromones in giant pandas.

Combined urine metabolomics and 16S rDNA sequencing analyses reveals physiological mechanism underlying decline in natural mating behavior of captive giant pandas

The decline in natural mating behavior is the primary reason underlying in the poor population growth of captive giant pandas. However, the influencing factors and underlying mechanisms remain unclear to data. It is speculated that the decline in natural mating behavior could be related to the psychological stress caused by captivity, which restricts their free choice of mates. In order to test this hypothesis, we performed urinary metabolomics analysis using Ultra-High-Performance Liquid Chromatography-Mass Spectrometry (UHPLC/-MS) combined with 16S rDNA sequencing for exploring the physiological mechanism underlying the decline in the natural mating behavior of captive giant panda. The results demonstrated that the decline in mating ability could be related to abnormalities in arginine biosynthesis and neurotransmitter synthesis. Additionally, the relative abundance of bacteria from the Firmicutes, Proteobacteria, and Actinobacteria phyla and the Acinetobacter, Weissella, and Pseudomonas genus was significantly reduced in the group with low natural mating behavior. These findings imply that the inhibition of arginine synthesis induced by environmental changes could be related to the poor libido and failure of mate selection in captive giant pandas during the breeding period. The results also demonstrate the relationship between the altered urinary microbes and metabolites related to arginine and neurotransmitter synthesis. These findings may aid in understanding the mechanism underlying environment-induced mate selection in captive giant pandas and propose a novel strategy for determining the sexual desire of giant pandas based on urinary microbes. The method would be of great significance in improving the natural reproductive success rate of captive giant pandas.

Successful captive breeding of a Malayan pangolin population to the third filial generation

Pangolins are threatened placental mammals distributed in Africa and Asia. Many efforts have been undertaken in the last century to maintain pangolins in captivity, but only a few of them succeeded in maintaining and keeping this species in a controlled environment. This study reports the first systematic breeding of the Critically Endangered Malayan pangolin (Manis javanica) in captivity. Our captive breeding approach successfully improved the reproductive rate for both wild and captive-born female pangolins. From 2016 to 2020, we had 33 wild pangolins and produced 49 captive-born offspring spanning three filial generations. The female offspring further bred 18 offspring, of which 14 (78%) were conceived during the first time of cohabitation with males, and four offspring were conceived during the second cohabitation event, suggesting that they may practice copulation-induced ovulation. We observed that captive-born female pangolins could reach sexual maturity at 7–9 months (n = 4), and male pangolins could mate and successfully fertilise females at nine months age (n = 1). We also observed a female pangolin conceiving on the eighth day after parturition (the fifth day after the death of its pup). Our captive pangolins had a female-biased sex ratio of 1:0.5 at birth, unlike other known captive-born mammals. Also, captive-born pangolins were generally more viable after successful weaning and had a similar gestation length (~185 days) to wild pangolins. Most importantly, we report the first self-sustaining captive population of Malayan pangolins, and this species has an efficient reproduction strategy. These advances provide more comprehensive information for people to understand pangolins, and have implications for conserving endangered Malayan pangolins and providing scientific guidance to the management of other pangolin species.

Yan et al. report on a successful captive breeding program for Critically Endangered Malayan pangolins, Manis javanica. Breeding pangolins in captivity is historically challenging and unsuccessful, highlighting the importance of this self-sustaining population.