Enterocytozoon bieneusi is the most prevalent microsporidian species that can cause zoonotic diseases in humans and animals. Despite receiving increasing attention in relation to domestic animals, there has been limited information on the infection burden of E. bieneusi in cervids. Altogether, 215 fecal samples collected from four deer species in Beijing, China were examined by nested- Polymerase Chain Reaction (PCR)targeting the internal transcribed spacer (ITS) region. The overall prevalence of E. bieneusi in deer was 21.9% (47/215), with 30.0% (24/80) in Pere David’s deer, 27.3% (15/55) in fallow deer, 12.5% (5/40) in sika deer, and 7.5% (3/40) in Chinese water deer. Thirteen E. bieneusi genotypes were identified, including six known (HLJD-V, MWC_d1, BEB6, CGC2, JLD-XV, and HND-I) and seven novel genotypes (BJED-I to BJED-V, BJFD, and BJCWD). A phylogenetic analysis showed that 38.3% of the isolates belonged to zoonotic Group 1. In addition, E. bieneusi infection was first detected in fallow deer and Chinese water deer, which could act as potential zoonotic reservoirs. Our findings suggest that E. bieneusi circulates in deer and might be of importance to public health.

The reintroduction of rare and endangered species is one of the most important approaches to conservation and ecosystem restoration, but it has still proven to be an adventurous undertaking and most reintroduction programmes fail, so successful demonstrations are needed. Père David's deer (Elaphurus davidianus, Milu in Chinese) could be considered one of conservation's great success stories, as this species' path on the road to extinction has been reversed by a combination of ex-situ conservation and successful re-introduction in China. The species had been consigned to an imperial hunting ground when the last Chinese herds were exterminated during the fall of the Qing Dynasty (1644–1912). Fortunately, a few of the last remaining individuals were sent to European zoos. From these animals, a herd was bred on the 14th Duke of Bedford's estate, Woburn Abbey, and between 1985 and 1987, and 38 Milu were donated back to China for re-introduction in Beijing Milu Park (BMP), the former imperial hunting ground. An additional 39 deer were released at Dafeng National Nature Reserve (DFNNR), Jiangsu Province in 1986. In both of these safe and protected locations, the Milu thrived allowing for over 700 Milu to be sent to a further 82 sites throughout the species' original Chinese range over the last 36 years. As a result, the Milu population totaled 9136 by 2021, with 2855 individuals now living back in the wild; while another 5681 individuals inhabit the DFNNR, and 186 reside in BMP. Wild Milu, however, still face significant conservation challenges. The population lacks genetic diversity, leading to severe inbreeding depression and carrying multiple risks, such as high miscarriage rates, a reduced lifespan, and susceptibility to disease. Environmental constraints such as pollution and habitat fragmentation further result in small, fragmented wild populations. Moreover, the species currently lacks a national level conservation master plan, the associated coordinated monitoring platforms, and breeding plans for China's captive populations. Finally, there is now a lack of international cooperation in the conservation of this species. We therefore call for both a national-level conservation master plan in China and international cooperation to develop a shared database and germplasm databank covering Milu across all countries with ex-situ populations, as crucial steps for securing the long-term conservation of Milu and preventing it from ever becoming “extinct in the wild” again.

Antlers are the sole mammalian organs capable of continuous regeneration. This distinctive feature has evolved into various biomedical models. Research on mechanisms of antler growth, development, and ossification provides valuable insights for limb regeneration, cartilage-related diseases, and cancer mechanisms. Here, ribonucleic acid sequencing (RNA-seq) and four-dimensional data-independent acquisition (4D DIA) technologies were employed to examine gene and protein expression differences among four tissue layers of the Chinese milu deer antler: reserve mesenchyme (RM), precartilage (PC), transition zone (TZ), cartilage (CA). Overall, 4611 differentially expressed genes (DEGs) and 2388 differentially expressed proteins (DEPs) were identified in the transcriptome and proteome, respectively. Among the 828 DEGs common to both omics approaches, genes from the collagen, integrin, and solute carrier families, and signaling molecules were emphasized for their roles in the regulation of antler growth, development, and ossification. Bioinformatics analysis revealed that in addition to being regulated by vascular and nerve regeneration pathways, antler growth and development are significantly influenced by numerous cancer-related signaling pathways. This indicates that antler growth mechanisms may be similar to those of cancer cell proliferation and development. This study lays a foundation for future research on the mechanisms underlying the rapid growth and ossification of antlers.

Background: Clostridium perfringens (C. perfringens) type A is a major cause of enteritis in farmed and wild deer populations, leading to significant economic losses in the deer industry. This bacterium produces toxins that damage the intestine. Methods: In this study, we performed transcriptome analysis by establishing an intestinal circulation model of the intestines of fallow deer (Dama Dama) inoculated with C. perfringens type A versus those not inoculated with C. perfringens type A. In a further step, we determined the protein content of immunoinflammation-related molecules by ELISA and the antioxidant capacity of the intestine to investigate the molecular mechanisms of C. perfringens type A-induced enteritis. Results: Transcriptome analysis revealed significant enrichment of pathways related to the haematopoietic system, oxidative stress, the immune system and intestinal tight junctions. Additionally, C. perfringens α-toxin enters the intestine and may be recognized by TLR6, activating the immune system, increasing the secretion of various cytokines and inflammasome components, inducing oxidative stress and damaging the intestine. Conclusions: This study provides a comprehensive transcriptomic basis for understanding the selective differential expression of genes in deer enteritis induced by C. perfringens type A and provides a broader guide for finding therapeutic approaches to deer enteritis.

Species rewilding, as a key strategy for rescuing endangered species and rebuilding wild populations, fundamentally relies on the behavioral plasticity of specific wildlife species. Although most current rewilding initiatives select optimal habitats, research on behavioral adaptation mechanisms in more challenging, extreme environments remains lacking. The Milu (Elaphurus davidianus), a typical wetland and plain species, naturally inhabits the warm marshlands of the Yangtze and Yellow River basins. In this study, using GPS tracking data, we focused on a population of rewilding Milu on the Inner Mongolia Plateau to investigate behavioral plasticity in terms of home range area, activity rhythm, and movement distance, aimed to elucidate their survival adaptation strategies within mid-elevation and cold environments. The results indicated significant seasonal and sex-based differences in both home range and movement distance: home ranges contract and movement distances are minimized during winter, while spatial activity expands markedly in summer—and continues to increase year by year following rewilding. During the study period, the number of daily activity peaks per individual ranged from zero to four. Furthermore, peak timing exhibited clear seasonal variation, with crepuscular patterns—morning and evening activity peaks—predominant across most months. Approximately three months after release, the activity rhythms of both males and females stabilized. These findings reveal key behavioral adjustments of Milu translocated to a mountainous, cold-temperate environment outside its original distribution range, and provide a scientific basis for long-term management and for assessing the ecological adaptability of this introduced population.

Reintroduction has been recognized as a vital approach to protecting and restoring wild populations of rare and endangered species. Although numerous reintroduction programs have been launched worldwide, in-depth studies on population establishment, dynamics, distribution patterns, and challenges remain limited. The Milu (Elaphurus davidianus), endemic to China and once declared Extinct in the Wild by the IUCN, has become one of the most successful examples of global endangered species reintroduction since the initiation of its recovery program in 1985. Focusing on the reintroduction project in the Poyang Lake basin—China’s largest freshwater lake—this study analyzed 14 years of monitoring data to examine the processes of population re-establishment, demographic trends, and spatiotemporal distribution of the species, while also identifying major ongoing challenges. Findings reveal the following: (1) the acclimatization process was essential for 10 individuals first reintroduced in 2013, and then 30 individuals joined to the growing population, followed by the largest-scale release of 47 in 2018, which finally led to eight consecutive years of natural reproduction, with a theoretically estimated population of 89 individuals until August 2025; (2) among 1697 individual sightings in 238 monitoring events, 952 records can be distinguished between male and female individuals (sex ratio = 1:1.63), yielding a mean herd size of 7.28 ± 0.68 individuals per sighting event—although numbers rose slightly in 2024, a declining trend was observed from 2019 to 2023 (from 11.26 to 5.13); (3) the Milu have expanded their range across eastern Poyang Lake, demonstrating a behavioral patterns of migrating out of the lake zone during flood seasons and returning in dry season; (4) the restoration of the Milu population is a systematic endeavor, in which government support and the participation of conservation professionals, scientists, volunteers, media, and the public are critical factors; and (5) ongoing threats such as human disturbance (e.g., habitat degradation) and climate change continue to jeopardize long-term population viability. This study offers important scientific insights into the recovery of endangered wildlife globally and underscores the essential role of governmental commitment, long-term monitoring, and multi-stakeholder collaboration in species reintroduction efforts.