Animals

26 pages, 514 KB

Open AccessReview

The Equine Reproductive Microbiota: Composition, Dynamics, Dysbiosis, and Implications for Fertility in Mares and Stallions

by Urtė Pelenė, Artūras Šiukščius, Rasa Nainienė, Inga Merkelytė and Rūta Šveistienė

Animals 2026, 16(9), 1414; https://doi.org/10.3390/ani16091414 - 5 May 2026

Abstract

The equine reproductive microbiota has emerged as an important factor influencing reproductive health and fertility in both mares and stallions. Traditionally, the equine uterus was considered sterile, and microbial presence was interpreted primarily in the context of infection. However, sequencing-based studies have demonstrated [...] Read more.

The equine reproductive microbiota has emerged as an important factor influencing reproductive health and fertility in both mares and stallions. Traditionally, the equine uterus was considered sterile, and microbial presence was interpreted primarily in the context of infection. However, sequencing-based studies have demonstrated that the reproductive tract, including the uterus and semen, contains detectable microbial communities or microbial DNA signatures, challenging this traditional paradigm. In mares, the vaginal microbiota is consistently dominated by Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria, whereas the uterine environment represents a low-biomass niche in which interpretation is complicated by contamination risk and the inability of sequencing-based methods to distinguish viable from nonviable microorganisms. Culture-based studies consistently identify opportunistic pathogens such as Streptococcus equi subsp. zooepidemicus, Escherichia coli, and Pseudomonas aeruginosa in association with endometritis and persistent breeding-induced endometritis, while sequencing-based studies suggest broader community-level dysbiosis rather than simple pathogen presence. In stallions, semen is not sterile and commonly contains taxa such as Porphyromonas, Corynebacterium, Peptoniphilus, and other opportunistic bacteria that may influence sperm quality and microbial transmission to mares during breeding. However, most reported associations remain correlative, and direct longitudinal evidence for persistent stallion-to-mare microbial transmission is limited. This review synthesizes current evidence on microbial composition, hormonal influences, dysbiosis, and reproductive implications of the equine reproductive microbiota, integrating culture-based and sequencing-based findings while emphasizing methodological limitations associated with low-biomass samples. Improved understanding of these microbial ecosystems may support more evidence-based reproductive diagnostics and microbiome-informed fertility management in horses. Full article

(This article belongs to the Special Issue The Role of Reproductive Microbiota in Animal Fertility and Reproductive Health)

► Show Figures

Figure 1

20 pages, 8307 KB

Open AccessArticle

Effects of RNA Interference-Mediated Silencing of the Insulin-Like Androgenic Gland Hormone Gene on Growth and Gonad Development in the Swimming Crab (Portunus trituberculatus)

by Weiren Zhang, Ronghua Li, Chuan He, Changkao Mu, Chunlin Wang, Ce Shi and Weiwei Song

Animals 2026, 16(9), 1413; https://doi.org/10.3390/ani16091413 - 5 May 2026

Abstract

The insulin-like androgenic gland (IAG) gene is considered a crucial factor in the process of sexual differentiation in decapod crustaceans. In this study, we characterized the structural features and ontogenetic expression profile of the IAG gene in the swimming crab P. trituberculatus ( [...] Read more.

The insulin-like androgenic gland (IAG) gene is considered a crucial factor in the process of sexual differentiation in decapod crustaceans. In this study, we characterized the structural features and ontogenetic expression profile of the IAG gene in the swimming crab P. trituberculatus (Pt-IAG). To further elucidate its biological roles, we performed long-term RNA interference (RNAi) to evaluate the physiological impacts of sustained Pt-IAG suppression. Results showed that the gene structure of Pt-IAG is conserved with the characteristic B-C-A polypeptide arrangement that is representative of decapod IAGs. Transcripts of Pt-IAG were detectable as early as the zygote stage, which may imply its potential role during early-stage development. Although no completesex reversal was observed, continuous knockdown of Pt-IAG resulted in a decrease in body weight and a delay in gonad development in both sexes, underscoring its pleiotropic role in coordinating growth and maturation. Furthermore, the silencing of Pt-IAG led to a significant downregulation of insulin-like growth factor-binding protein (Pt-IGFBP), and a decrease in insulin-receptor (Pt-IR) expression was observed in males. Notably, the Pt-IR gene was not detected in female ovaries. These findings suggest that IAG may modulate male development through an insulin-like signaling axis; however, the absence of ovarian Pt-IR expression implies the potential existence of alternative regulatory pathways in females. Collectively, this study identifies a dual regulatory role of IAG in both growth and reproduction, providing a specific theoretical basis for developing sex-control and growth-optimization strategies in crab aquaculture. Full article

(This article belongs to the Section Aquatic Animals)

► Show Figures

Figure 1

15 pages, 769 KB

Open AccessArticle

Evaluation and Selection of Stable Reference Genes for qRT-PCR Analysis in Different Tissues of Mugilogobius chulae Under Pollutant Exposure

by Zhongdian Dong, Jiahao Gao, Xiaobin Li, Zhishan Chen, Jianjun Li, Jian Liao, Yanping Zhang, Zhongduo Wang, Yusong Guo and Ning Zhang

Animals 2026, 16(9), 1412; https://doi.org/10.3390/ani16091412 (registering DOI) - 5 May 2026

Abstract

Reliable normalization is essential for accurate quantitative real-time PCR (qRT-PCR) analysis, yet suitable reference genes have not been systematically evaluated in Mugilogobius chulae, an emerging marine experimental fish used in physiological and environmental research. In this study, 17 candidate reference genes were [...] Read more.

Reliable normalization is essential for accurate quantitative real-time PCR (qRT-PCR) analysis, yet suitable reference genes have not been systematically evaluated in Mugilogobius chulae, an emerging marine experimental fish used in physiological and environmental research. In this study, 17 candidate reference genes were evaluated in five tissues (brain, gill, gonad, intestine, and liver) of sexually mature male and female M. chulae under solvent control (DMSO), bisphenol A (BPA), cadmium (Cd), and sulfamethazine (SMX) treatment conditions. Gene-expression stability was assessed using the comparative ΔCt method, NormFinder, geNorm, BestKeeper, and the integrated RefFinder ranking. The results showed that reference-gene stability was strongly tissue-specific and analysis-dependent. The integrated RefFinder analysis identified eif3h, rpl7, rps4x, stau1, and ef1y as the most stable genes in the pooled dataset, whereas ube2, hprt1l, and aldob were the least stable. geNorm analysis indicated that two reference genes were sufficient for brain, gill, intestine, and liver, whereas four were required for the gonad and six for cross-tissue comparisons. These findings provide the first systematic basis for reference-gene selection in M. chulae and establish an important methodological foundation for future qRT-PCR studies in this species, particularly in research on endocrine disruption, reproductive physiology, and marine ecotoxicology. Full article

(This article belongs to the Special Issue Sustainable Aquaculture: A Functional Genomic Perspective)

► Show Figures

Figure 1

19 pages, 6457 KB

Open AccessArticle

Protective Effect of Synbiotic Supplementation Against Salmonella Typhimurium Infection in Young Broiler Chickens

by Walter Rivera Pérez, Elías Barquero Calvo, Aida Chaves Hernández and Catalina Salas Duran

Animals 2026, 16(9), 1411; https://doi.org/10.3390/ani16091411 - 5 May 2026

Abstract

Salmonella infection in poultry remains a major concern due to its economic impact and public health risks. Synbiotics have emerged as a natural strategy to improve gut health and resistance to enteric pathogens. This study evaluated the immune response and early protective effects [...] Read more.

Salmonella infection in poultry remains a major concern due to its economic impact and public health risks. Synbiotics have emerged as a natural strategy to improve gut health and resistance to enteric pathogens. This study evaluated the immune response and early protective effects of a synbiotic in broiler chickens using a reduced in vivo model of Salmonella Typhimurium infection. A total of 44 broiler chickens were randomly assigned to four dietary treatments: control (CT), control plus synbiotic (CT + Syn), challenged (ST), and challenged plus synbiotic (ST + Syn). Birds were challenged at 7 days of age and euthanized at day 12 for sample collection. Synbiotic supplementation reduced bacterial colonization and adhesion in the ileum, as assessed by intestinal content isolation and immunofluorescence analysis. Additionally, the synbiotics mitigated lesion severity in the intestine, liver, and heart, increased anti-inflammatory IL-10 expression, and reduced pro-inflammatory cytokines IL-1β and TNF-α. Ileal histomorphometry showed increased epithelial height in the ST + Syn birds, while intestinal permeability was not affected. Improved body weight was also observed compared to the challenged birds without supplementation. In conclusion, synbiotic supplementation provided early protection against S. Typhimurium infection by modulating immune responses, preserving intestinal morphology, and supporting weight gain in broiler chickens. Full article

(This article belongs to the Special Issue Probiotics and Synbiotics in Poultry: Impacts on Gut Microbiota)

► Show Figures

Figure 1

14 pages, 902 KB

Open AccessFeature PaperArticle

Birth Weight and Early Weight Changes in Newborn Dogs: Analyzing Key Influencing Factors in Dobermann Puppies

by Jasmine Fusi, Roberta Bucci, Claudia Scabrosetti, Massimo Faustini and Maria Cristina Veronesi

Animals 2026, 16(9), 1410; https://doi.org/10.3390/ani16091410 - 5 May 2026

Abstract

Birthweight (BW) and early weight changes are important prognostic factors in dog neonatology, but are influenced by the breed. The present study aimed to evaluate BW and early growth in a single breed, Dobermann, and single breeding facility for a better evaluation of [...] Read more.

Birthweight (BW) and early weight changes are important prognostic factors in dog neonatology, but are influenced by the breed. The present study aimed to evaluate BW and early growth in a single breed, Dobermann, and single breeding facility for a better evaluation of data and analysis of influencing factors. In 364 puppies born by elective cesarean section, the ROC curve and cut-off weight values associated with the risk for death within 15 days after birth were defined for BW and Day 1 weight (D1W). Both BW and D1W were influenced by newborn’s sex (p < 0.05), maternal age (p < 0.05) and maternal bodyweight (p < 0.05), litter size (p < 0.05), and “litter effect” (p < 0.05). The weight charts for the first 15 days after birth were constructed for female and male puppies, and weight percentage variation analysis of the first 5 days after birth showed that the nadir of weight loss occurred around 1 day after birth, followed by BW recovery within 3 days, and doubling BW around 12–14 days. Therefore, BW (p < 0.001), D1W (p < 0.001) and early weight changes are important factors for prognosis and growth monitoring, allowing the prompt detection of those puppies needing special care. However, the influences of sex-related differences and maternal factors must be considered. Full article

(This article belongs to the Section Veterinary Clinical Studies)

► Show Figures

Figure 1

17 pages, 1665 KB

Open AccessCommunication

Preoperative Cardiac Risk Stratification in Dogs with Mammary Tumors Using Two-Dimensional Speckle Tracking Echocardiography: A Pilot Study

by Didem Algan, Tuğba Varlik, Hüseyin Tan, Pelin Erden, Lina Hamabe, Ryou Tanaka and Zeki Yilmaz

Animals 2026, 16(9), 1409; https://doi.org/10.3390/ani16091409 - 4 May 2026

Abstract

Although breast cancer has been associated with subclinical left ventricular dysfunction in humans, the cardiac effects of CMTs remain poorly defined. This pilot, exploratory (communication) study compared clinical and echocardiographic parameters between dogs with CMTs and healthy controls and assessed the feasibility of [...] Read more.

Although breast cancer has been associated with subclinical left ventricular dysfunction in humans, the cardiac effects of CMTs remain poorly defined. This pilot, exploratory (communication) study compared clinical and echocardiographic parameters between dogs with CMTs and healthy controls and assessed the feasibility of combining myocardial deformation imaging with exploratory data-driven analysis for preoperative cardiac assessment. All dogs underwent a standardized clinical and echocardiographic assessment, including two-dimensional speckle-tracking echocardiography (2D-STE). Given the limited sample size, analyses were designed to generate hypotheses rather than to provide definitive predictive conclusions. Exploratory machine learning modeling (XGBoost), receiver operating characteristic (ROC) analysis, calibration, and decision curve analysis were performed as proof-of-concept approaches without external validation. Despite normal conventional systolic indices, dogs with CMTs exhibited reduced global longitudinal strain (GLS) and mitral annular plane systolic excursion (MAPSE) (p < 0.01), suggesting subclinical systolic dysfunction. Deformation-derived parameters appeared more sensitive for detecting subtle myocardial alterations within this cohort. The exploratory machine learning model demonstrated moderate discrimination (AUC-ROC = 0.75); however, these findings are preliminary and should not be interpreted as evidence of clinical predictive performance. Overall, these results suggest that conventional systolic indices may underestimate early myocardial changes in dogs with CMTs. This communication highlights the feasibility of integrating deformation imaging with exploratory analytical approaches and provides a basis for future large-scale, validated studies in veterinary cardio-oncology. Full article

(This article belongs to the Section Veterinary Clinical Studies)

► Show Figures

Figure 1

24 pages, 9986 KB

Open AccessArticle

Tea Saponin Exerts Dose-Dependent Dual Effects on Growth and Hepatic Health in Hybrid Grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) Fed a High-Lipid, Low-Protein Diet via Redox-Immune Regulation

by Shengrong Guo, Jun Yu, Lili Shi, Beiping Tan, Shuang Zhang and Xiaobo Yan

Animals 2026, 16(9), 1408; https://doi.org/10.3390/ani16091408 - 4 May 2026

Abstract

High-lipid, low-protein diets are economically advantageous in aquaculture costs but often induce hepatic damage, immunosuppression and metabolic disorders in carnivorous fish like hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂). Tea saponin (TS) is a bioactive triterpenoid from camellia seed meal [...] Read more.

High-lipid, low-protein diets are economically advantageous in aquaculture costs but often induce hepatic damage, immunosuppression and metabolic disorders in carnivorous fish like hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂). Tea saponin (TS) is a bioactive triterpenoid from camellia seed meal with excellent lipid-lowering and anti-inflammatory effects. The purpose of the current study was to investigate the dose-dependent impacts of TS supplementation at 0% (control, T0), 0.05% (T5), 0.10% (T10), 0.15% (T15), and 0.20% (T20) in diets formulated to contain 42% crude protein and 16% crude lipid on juvenile hybrid grouper (17.51 ± 0.03 g), with three replicate tanks per treatment, over a 4-week feeding trial. The results showed that low TS supplementation (0.05%) improved growth, with the effect limited to final average weight (FAW), whereas higher doses (≥0.15%) reduced weight gain. The T5 group exhibited the highest hepatic total antioxidant capacity and superoxide dismutase activity, consistent with the corresponding gene expression, and the lowest malondialdehyde and reactive oxygen species levels. Lysozyme activity and immunoglobulin M content were significantly higher in T5–T15 groups (p < 0.05). Furthermore, appropriate TS significantly upregulated anti-inflammatory cytokines (p < 0.05) and downregulated pro-inflammatory factors. Histologically, 0.10% TS reduced inflammatory infiltration, while high doses caused hepatocyte rupture and lipid vacuolation. Transcriptomic analysis further elucidated that the beneficial effects of low-dose TS were linked to the activation of PPAR signaling, fatty acid catabolism, and cellular quality control pathways, while high-dose TS triggered stress-related and biosynthetic programs. In conclusion, moderate TS supplementation (0.05–0.10%) ameliorated diet-induced oxidative stress and immunosuppression, improved growth performance and anti-inflammatory factor expression, whereas over-addition inhibited growth and exacerbated hepatic damage. Based on a quadratic model, the optimal dietary TS level for maximizing growth under this low-protein, high-lipid regimen is estimated at 0.055%. Full article

(This article belongs to the Special Issue Genomics, Evolution, and Biodiversity of Fishes)

► Show Figures

Figure 1

18 pages, 55736 KB

Open AccessArticle

Developmental Comparative Analysis of Enteroendocrine Hormone Immunoreactive Cells in the Abomasum and Small Intestine of Holstein–Friesian Bulls

by Ligia Janicka, Aleksandra Dajnowska, Katarzyna Woźniak, Cezary Osiak-Wicha, Katarzyna Kras, Iwona Łuszczewska-Sierakowska and Marcin B. Arciszewski

Animals 2026, 16(9), 1407; https://doi.org/10.3390/ani16091407 - 4 May 2026

Abstract

Within the complex regulatory network of the gastrointestinal tract, enteroendocrine cells play a fundamental role in coordinating digestive processes and maintaining metabolic balance. These cells produce a wide range of hormones that influence secretion, motility, and nutrient utilization, constituting an essential component of [...] Read more.

Within the complex regulatory network of the gastrointestinal tract, enteroendocrine cells play a fundamental role in coordinating digestive processes and maintaining metabolic balance. These cells produce a wide range of hormones that influence secretion, motility, and nutrient utilization, constituting an essential component of gastrointestinal physiology in ruminants. Despite the growing interest in the role of endocrine regulation in digestive system function, comprehensive studies evaluating enteroendocrine cell populations across different segments of the gastrointestinal tract in cattle remain limited. In particular, the organization of these cell populations in key digestive segments such as the abomasum and small intestine requires further investigation to better understand their functional significance. The aim of the present study was to provide a comparative characterization of selected enteroendocrine cell populations in the abomasum and small intestine of young and adult Holstein–Friesian bulls. Tissue samples collected from the abomasum, duodenum, jejunum, and ileum were subjected to histological and immunohistochemical analyses. Chromogranin A (CgA) was used as a general marker of enteroendocrine cells, and the number of cells immunoreactive to CgA as well as to gastrin, secretin, somatostatin (SOM), glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-1 (GLP-1) was quantified in the examined segments of the gastrointestinal tract. All types of immunoreactive cells were counted using a standardized quantitative method based on the assessment of positively stained cells in randomly selected microscopic fields of histological sections. The results revealed clear differences in the number of enteroendocrine cells between the analyzed segments of the gastrointestinal tract as well as between the studied age groups. These findings indicate regional and age-related variation in enteroendocrine cell populations within the gastrointestinal tract and highlight their association with the functional organization of individual segments of the digestive system. Full article

(This article belongs to the Special Issue Feed Additives for Farm Animals: Gut Microbiome, Metabolism, Neuroendocrine Regulation, and Product Quality)

► Show Figures

Figure 1

29 pages, 3688 KB

Open AccessReview

Research Progress on Mammalian Oocyte Vitrification: From Damage Mechanisms to Optimization Strategies

by Kelin Song, Li Wang, Feng Yang, Hongqian Zhu, Qiuyu Meng, Xuelei Han, Ruimin Qiao, Jun Bai, Shuangbao Gun, Tong Yu and Xinjian Li

Animals 2026, 16(9), 1406; https://doi.org/10.3390/ani16091406 - 3 May 2026

Abstract

With the continuous advancement in reproductive biology, oocyte vitrification has become a critical technology for preserving female germplasm and protecting it from environmental disruptions. This technique also eliminates temporal and spatial constraints in animal embryo engineering research. However, during the vitrification of animal [...] Read more.

With the continuous advancement in reproductive biology, oocyte vitrification has become a critical technology for preserving female germplasm and protecting it from environmental disruptions. This technique also eliminates temporal and spatial constraints in animal embryo engineering research. However, during the vitrification of animal oocytes, exposure to low temperatures and high concentrations of cryoprotectants can cause various forms of damage, including cytoskeletal disruption, spindle abnormalities, mitochondrial dysfunction, apoptosis, oxidative stress and epigenetic modifications. These issues are now understood to severely restrict the subsequent developmental competence of oocytes, resulting in lower cleavage and blastocyst formation rates than those of fresh oocytes. Currently, the mechanisms of cryodamage in vitrified oocytes remain poorly understood, and standardized strategies to enhance vitrification efficiency have yet to be firmly established. This review provides a formal overview of the physiological factors underlying oocyte sensitivity to vitrification, alongside the mechanisms of cryodamage and the variables influencing post-thaw survival and reproductive success. It evaluates strategies for mitigating vitrification-induced stress, compares interspecies differences, and addresses current research limitations. By identifying future directions, this review offers new insights for optimizing mammalian oocyte cryopreservation techniques. Full article

(This article belongs to the Special Issue Advances in Cryopreservation of Livestock Oocytes and Embryos)

14 pages, 485 KB

Open AccessArticle

Pre-Intervention Assessment of Toxocara Infection in Dogs in Vietnam: A Community-Based Cross-Sectional Study

by Minh-Trang Thi Hoang, Dinh Ng-Nguyen, Ketsarin Kamyingkird, Van-Phuong Ngo and Tawin Inpankaew

Animals 2026, 16(9), 1405; https://doi.org/10.3390/ani16091405 - 3 May 2026

Abstract

Dogs are key reservoirs of zoonotic infections, including Toxocara canis, a widely distributed parasite of major public health concern. In Vietnam, the parasite is highly prevalent in dog populations and humans. Epidemiological studies assessing infection and associated factors are essential to better [...] Read more.

Dogs are key reservoirs of zoonotic infections, including Toxocara canis, a widely distributed parasite of major public health concern. In Vietnam, the parasite is highly prevalent in dog populations and humans. Epidemiological studies assessing infection and associated factors are essential to better understand transmission and to inform effective control strategies. We conducted a cross-sectional baseline survey to assess Toxocara infection in dogs in rural Vietnam. Fecal samples from 371 dogs were examined using centrifugal flotation (Sheather’s solution, specific gravity 1.2) and conventional polymerase chain reaction (PCR), alongside structured questionnaires on dog demographics and management. Using combined copromicroscopic and molecular methods, the overall prevalence of Toxocara infection was 44.7% (95% CI: 39.6–50.0). By microscopy alone, 29.9% (95% CI: 25.4–34.9) of samples were positive, while PCR detected Toxocara DNA in 41.2% (95% CI: 36.2–46.5) of dogs. Molecular analysis identified T. canis in 35.9% (95% CI: 31.0–41.0) and T. cati in 10.5% (95% CI: 7.7–14.2) of tested dogs. Dog age and deworming status were independently associated with PCR-detected T. canis infection. The elevated likelihood of infection among dogs that have never been dewormed highlights the importance of canine deworming. Questionnaire findings indicating suboptimal dog care and management highlight the need for community public health education to promote responsible ownership and reduce transmission risk. This baseline assessment provides essential evidence to inform targeted interventions and improve understanding of Toxocara transmission in endemic settings. Full article

(This article belongs to the Special Issue Zoonotic Parasites at the Human-Animal Interface: Advances in Epidemiology, Transmission, Diagnosis, and Treatment)

15 pages, 840 KB

Open AccessFeature PaperArticle

Native Fish Inclusion Promotes Nutrient Retention and Productivity in a Biofloc-Based Aquaponic System

by Adolfo Jatobá, Bruno Corrêa da Silva, Felipe Boéchat Vieira, Marco Shizuo Owatari, Leonardo Alexander Krause, Amanda Dartora, Maísa de Lima Lasala, Keren Fagundes Morais and Jaqueline I. A. de Andrade

Animals 2026, 16(9), 1404; https://doi.org/10.3390/ani16091404 (registering DOI) - 3 May 2026

Abstract

The integration of multiple species has been proposed as a strategy to improve resource use efficiency in intensive aquaculture systems. This study evaluated the inclusion of a native fish species, yellowtail lambari (Astyanax bimaculatus), in a biofloc-based aquaponic system co-cultivating Nile [...] Read more.

The integration of multiple species has been proposed as a strategy to improve resource use efficiency in intensive aquaculture systems. This study evaluated the inclusion of a native fish species, yellowtail lambari (Astyanax bimaculatus), in a biofloc-based aquaponic system co-cultivating Nile tilapia (Oreochromis niloticus) and lettuce (Lactuca sativa var. capitata). The experiment was conducted over 35 days using eight experimental units with two treatments (with and without lambari) and four replicates. Water quality, zootechnical performance, lettuce growth, hematological parameters of tilapia, and nitrogen and phosphorus retention were assessed. The presence of lambari was associated with lower total ammonia nitrogen, toxic ammonia, and total suspended solids, particularly during the final stage of the experimental period (p < 0.05), as well as reduced pH and alkalinity, likely reflecting increased microbial activity. Lettuce cultivated in the lambari treatment showed higher final weight, leaf height, and total biomass (p < 0.05), resulting in increased system productivity. No significant differences were observed in growth performance or hematological parameters of Nile tilapia (p > 0.05). In addition, nitrogen and phosphorus retention at the system level were higher in the lambari treatment (p < 0.05), although no differences were detected when fish and plants were evaluated separately. These results indicate that the inclusion of a native fish species can influence nutrient retention and productivity in biofloc-based aquaponic systems without compromising the performance of the primary cultured species. Full article

(This article belongs to the Special Issue Innovations in Aquaculture: New Technologies, Culture Systems and Integration of Emerging Species)

► Show Figures

Figure 1

15 pages, 2006 KB

Open AccessArticle

Sustainable Upcycling of Swine Wastewater Sludge: Using Thermal and Citrate Pretreatment to Enhance Volatile Fatty Acid Production

by Wei-Chen Chen and Jung-Jeng Su

Animals 2026, 16(9), 1403; https://doi.org/10.3390/ani16091403 - 3 May 2026

Abstract

The sustainable management of intensive swine farming is currently bottlenecked by the difficult valorization of metal-rich wastewater sludge. The structural rigidity of this sludge, stabilized by divalent cation bridging, severely limits its anaerobic digestion and overall resource recovery. To optimize the manure management [...] Read more.

The sustainable management of intensive swine farming is currently bottlenecked by the difficult valorization of metal-rich wastewater sludge. The structural rigidity of this sludge, stabilized by divalent cation bridging, severely limits its anaerobic digestion and overall resource recovery. To optimize the manure management chain, this study comprehensively evaluated various physical and chemical pretreatments to identify the most effective disintegration strategy for enhanced volatile fatty acid (VFA) production. Among the tested conditions, the coupling of thermal hydrolysis with citrate chelation (T/SC) was the most effective, achieving the highest disintegration degree (12.37%) and biopolymer solubilization. Mechanism analysis revealed that, unlike traditional alkaline treatments, which are limited by the severe reprecipitation of magnesium and phosphate, citrate effectively sequestered bridging cations (Ca²⁺ and Mg²⁺) via ligand exchange. This synergistic disintegration accelerated the fermentation kinetics, enhancing the total VFA yield 2-fold (1293 mg/L) compared to the control group while maintaining a high-value, butyrate-dominant product profile. These findings demonstrate that targeting ionic bridges via ligand-promoted dissolution provides a highly practical and sustainable strategy to maximize resource recovery and nutrient cycling from metal-laden livestock wastes. Full article

(This article belongs to the Special Issue Strategies for Integrating Waste Recycling and Resource Recovery in Animal Farming)

► Show Figures

Figure 1

16 pages, 9331 KB

Open AccessArticle

Molecular Characterization of Representative CPV-2c Isolates and Establishment of VP2-Targeted Nanobody-Based Immunodetection Tools

by Liangkai Liu, Maohua Xia, Chengyao Hou, Danyu Chen, Chengyao Li, Xinggui Chen, Qinyuan Chu, Yue Sun, Shujun Liu, Yuqing Li, Hanlin Wang, Yan Zhu, Mengfang Yang, Hongning Wang, Caiwu Li and Xin Yang

Animals 2026, 16(9), 1402; https://doi.org/10.3390/ani16091402 - 3 May 2026

Abstract

Although canine parvovirus (CPV) vaccination has been widely implemented, CPV continues to circulate in dog populations and poses a potential cross-species transmission risk to wildlife, including giant pandas. Recent increases in CPV-2c detection in China highlight the need for molecular surveillance and standardized [...] Read more.

Although canine parvovirus (CPV) vaccination has been widely implemented, CPV continues to circulate in dog populations and poses a potential cross-species transmission risk to wildlife, including giant pandas. Recent increases in CPV-2c detection in China highlight the need for molecular surveillance and standardized immunoreagents for diagnosis and epitope mapping. This study aimed to isolate a representative CPV-2c strain from China and develop VP2-targeted nanobody-based recognition molecules to support antigen monitoring and detection optimization. Canine and giant panda samples were collected in Sichuan Province, and CPV was isolated in F81 cells, followed by VP2 gene sequencing and phylogenetic analysis. A secretion expression system in Bacillus subtilis was established to produce VP2-targeting nanobodies, and a canine Fc-fused format of Nb10 (Nb10-Fc) was constructed. Immunoreactivity was evaluated via immunoassays, and structural modeling and molecular docking were performed to predict binding interfaces. The results showed that CPV-2c was the dominant genotype in Sichuan, with CPV L4 being a representative strain that exhibited 100% identity in VP2 with a giant panda-derived CPV-2c strain. Nb10 and Nb10-Fc demonstrated strong reactivity in Western blotting and immunofluorescence assays. The Fc-fusion improved detection sensitivity, offering potential in vivo application benefits. This study provides a standardized VP2-specific nanobody and molecular system for CPV-2c surveillance, antigenic studies, and diagnostic optimization. Full article

(This article belongs to the Section Companion Animals)

► Show Figures

Figure 1

30 pages, 6172 KB

Open AccessArticle

Negative Phonotaxis Behavior of Juvenile Grass Carp (Ctenopharyngodon idella) to Different Acoustic Stimuli in Natural Aquatic Environments

by Jiaxin Li, Shenwei Zhang, Xuan Wang, Ji Yang, Guoyong Liu and Lixiong Yu

Animals 2026, 16(9), 1401; https://doi.org/10.3390/ani16091401 - 3 May 2026

Abstract

Hydraulic engineering structures can threaten freshwater fish by entraining them into hazardous areas. Acoustic barriers have been proposed as a non-physical method to guide fish away from these zones. In this study, we investigated the behavioral responses of juvenile grass carp to different [...] Read more.

Hydraulic engineering structures can threaten freshwater fish by entraining them into hazardous areas. Acoustic barriers have been proposed as a non-physical method to guide fish away from these zones. In this study, we investigated the behavioral responses of juvenile grass carp to different acoustic stimuli under semi-natural conditions using outdoor net cages. Four sound types were tested: a 1000 Hz pure tone and three broadband sounds, including Alligator sinensis hissing, pile-driving noise, and outboard motor noise. Behavioral responses were quantified using response frequency, total midline crossings, first-response time, maximum swimming speed, and average swimming speed. The results showed that Alligator sinensis hissing elicited the highest number of midline crossings, representing the strongest behavioral response among all tested sounds. In addition, both Alligator sinensis hissing and outboard motor noise induced significantly stronger avoidance responses than the pure tone or pile-driving noise, as indicated by higher response frequency and faster swimming speeds. Furthermore, manipulation of pulse repetition intervals in the most effective deterrent sounds generated a novel broadband sound, which altered fish distribution patterns and elicited avoidance behavior. These findings indicate that both sound type and temporal structure influence negative phonotaxis behavior in grass carp and provide experimental evidence for the optimization of acoustic barriers in fish management. Full article

(This article belongs to the Section Aquatic Animals)

► Show Figures

Figure 1

13 pages, 8649 KB

Open AccessFeature PaperArticle

Impact of Dietary Inclusion with Cocrystal Essential Oil on Growth Performance, Nutrient Digestibility, Intestinal Morphology, and Antioxidant Status in Weaned Piglets

by Yifei Sun, Jun Chen, Qiuting Yin, Pengbo Liang, Jinming You and Tiande Zou

Animals 2026, 16(9), 1400; https://doi.org/10.3390/ani16091400 - 3 May 2026

Abstract

This study assessed the impact of cocrystal essential oil (CEO) inclusion on growth performance, nutrient digestibility, intestinal morphology, and antioxidant status in weaned piglets. Ninety-six weaned piglets were assigned to four groups (n = 8, three piglets per pen). The piglets in the [...] Read more.

This study assessed the impact of cocrystal essential oil (CEO) inclusion on growth performance, nutrient digestibility, intestinal morphology, and antioxidant status in weaned piglets. Ninety-six weaned piglets were assigned to four groups (n = 8, three piglets per pen). The piglets in the four groups were fed basal diets added with 0, 120, 180, or 240 mg/kg of CEO, respectively, over a 28-day trial period. Results showed that during weeks 1–2, piglets in the 240 mg/kg CEO group exhibited a lower diarrhea rate and diarrhea index compared to the control group (p < 0.05). In weeks 3–4, the 180 and 240 mg/kg CEO groups demonstrated a reduced diarrhea rate and diarrhea index compared to the control group (p < 0.05). Relative to the control group, the apparent total tract digestibility (ATTD) of dry matter was elevated in piglets fed diets added with 120, 180, or 240 mg/kg CEO at both day 14 and day 28 (p < 0.05). Additionally, the ATTD of crude protein was elevated in the 120 mg/kg CEO group at day 14 and in the 180 mg/kg CEO group at day 28 (p < 0.05). Regarding intestinal morphology, supplementation with 180 or 240 mg/kg CEO increased jejunal villus height (VH) and the villus height to crypt depth (VH/CD) ratio compared with the control group (p < 0.05). Furthermore, 240 mg/kg CEO supplementation augmented the ileal VH/CD ratio relative to the control group (p < 0.05). For antioxidant status, 180 mg/kg CEO supplementation elevated serum glutathione peroxidase (GSH-Px) activity in piglets relative to the control group (p < 0.05). Importantly, no differences were found between the 180 mg/kg and 240 mg/kg CEO groups across all measured parameters (p > 0.05). In conclusion, dietary inclusion with 180 mg/kg CEO is recommended for weaned piglets, given its comprehensive benefits in alleviating diarrhea, improving nutrient digestibility, enhancing intestinal morphology, and bolstering antioxidant status. Full article

(This article belongs to the Section Pigs)

► Show Figures

Figure 1

19 pages, 2134 KB

Open AccessArticle

Multiscale Structural Evolution and Digestion Kinetics of Starch in Commercial Swine Compound Feed as Affected by Steam Conditioning Temperature and Retention Time

by Junhua Wu, Fanglei Zou, Wei Wang, Liangju Wang and Hongying Wang

Animals 2026, 16(9), 1399; https://doi.org/10.3390/ani16091399 - 3 May 2026

Abstract

Steam conditioning is a key hydrothermal process for ensuring the quality of pelleted commercial swine compound feed. However, the molecular evolution of starch during processing remains poorly understood, particularly under the industrial constraints of limited moisture and complex substrates. This study quantified the [...] Read more.

Steam conditioning is a key hydrothermal process for ensuring the quality of pelleted commercial swine compound feed. However, the molecular evolution of starch during processing remains poorly understood, particularly under the industrial constraints of limited moisture and complex substrates. This study quantified the effects of conditioning temperature (60–90 °C) and retention time (2–4 min) on starch structural reorganization across multiple length scales and in vitro digestion kinetics in pig diets. Structural evolution exhibited a nonlinear, temperature-driven pattern, with the temperature region around 80 °C representing a critical transition in structural reorganization. Although high-temperature conditioning (90 °C) increased the initial digestion rate, a nonlinear structure–digestion response was observed: final digestibility decreased, and resistant starch content rebounded. Microstructural analyses revealed that severe heat treatment was associated with the possible formation of amylose–lipid complexes (V-type crystallinity) and a more continuous protein-associated matrix, which may have imposed additional physical constraints on enzymatic hydrolysis. Consequently, maximizing starch gelatinization does not necessarily guarantee optimal in vitro digestibility. These findings integrate multiscale structural analysis with digestion kinetics, providing a mechanistic basis for balancing energy consumption, pellet quality, and nutritional value in the feed industry. Full article

(This article belongs to the Section Animal System and Management)

► Show Figures

Figure 1

27 pages, 4942 KB

Open AccessArticle

Ancestral BG1 Alleles and Structural Conservation Ensure Immune-Related Genetic Resilience in Southeast Asian Chicken Lineages

by Anh Huynh Luu, Trifan Budi, Worapong Singchat, Chien Tran Phuoc Nguyen, Thitipong Panthum, Nivit Tanglertpaibul, Kanithaporn Vangnai, Aingorn Chaiyes, Chotika Yokthongwattana, Chomdao Sinthuvanich, Orathai Sawatdichaikul, Kyudong Han, Narongrit Muangmai, Darren K. Griffin, Prateep Duengkae, Ngu Trong Nguyen and Kornsorn Srikulnath

Animals 2026, 16(9), 1398; https://doi.org/10.3390/ani16091398 - 3 May 2026

Abstract

Chicken (Gallus gallus domesticus) domestication, likely associated with dry-rice farming in central Thailand, has led to substantial loss of ancestral immune-related genetic diversity in commercial chicken lineages. This study addresses allelic loss by providing the first comprehensive analysis of the highly [...] Read more.

Chicken (Gallus gallus domesticus) domestication, likely associated with dry-rice farming in central Thailand, has led to substantial loss of ancestral immune-related genetic diversity in commercial chicken lineages. This study addresses allelic loss by providing the first comprehensive analysis of the highly polymorphic BG1 gene, an MHC-linked marker across the wild–domestic interface in Thailand and Vietnam, using high-depth Illumina amplicon sequencing. Genomic DNA from 47 Thai and Vietnamese chicken populations was extracted using a salting-out protocol following ethical sampling. Allelic variation was examined by targeting the BG1 intron 15–exon 16 region using triplicate PCR and Salus Pro NGS sequencing. Evolutionary dynamics and selection pressures were analyzed using AmpliSAS, MrBayes, and Datamonkey, while AlphaFold 3 was used to predict and validate 3D protein structures. We identified 98 novel alleles and 172 polymorphic sites within the BG1 intron 15–exon 16 region encoding an Ig-like domain. Extensive allele sharing between indigenous chickens and red junglefowl indicated strong balancing selection and trans-species polymorphism. Selection analyses showed that purifying selection conserved structural integrity at codons 9, 13, and 18, while variation at other sites enhanced immune recognition. AlphaFold 3 modeling confirmed conservation of the β-sandwich fold across variants, maintaining stability of the Immunoreceptor Tyrosine-based Inhibition Motif (ITIM). Thus, despite the regional gene flow, geographic isolation has shaped distinct signatures, as evidenced by the presence of 38 unique Thai and 9 unique Vietnamese alleles in addition to breed-specific private markers in the Betong (BG1*TH88), Decoy (BG1*TH91), and Tre (BG1*VN54) populations. A notable adaptive outlier under positive selection (ω = 1.357) was detected in the Dong Tao population, suggesting a recent selective sweep. These findings support the mission of the Siam Chicken Bioresource Project (SCBP) to utilize indigenous breeds as genetic reservoirs and provide a molecular basis for restoring resilience traits in domestic poultry to enhance global food security. Full article

(This article belongs to the Section Animal Genetics and Genomics)

► Show Figures

Figure 1

18 pages, 4618 KB

Open AccessArticle

Establishment of a Quadruplex RT-qPCR Method for the Detection of All Lineages of PPRV

by Jiao Xu, Jiani Li, Qinghua Wang, Jiamin Zhou, Shuang Liu, Yingli Wang, Jiarong Yu, Jingyue Bao and Lin Yang

Animals 2026, 16(9), 1397; https://doi.org/10.3390/ani16091397 - 3 May 2026

Abstract

Peste des petits ruminants (PPR) is an infectious disease with high morbidity and mortality rates, and four distinct lineages have been discovered in different regions globally. In this study, a quadruplex RT-qPCR method capable of differentiating all four lineages of PPRV was established. [...] Read more.

Peste des petits ruminants (PPR) is an infectious disease with high morbidity and mortality rates, and four distinct lineages have been discovered in different regions globally. In this study, a quadruplex RT-qPCR method capable of differentiating all four lineages of PPRV was established. By screening specific conserved regions across all viral genomes, we designed primers, as well as four TaqMan probes capable of distinguishing all lineages. The established method underwent validation of its relevant characteristics. The sensitivity of the detection method was determined by testing plasmid serial dilutions ranging from 10⁸ to 10⁰ copies/μL; results showed that the method could detect as few as 10 copies per microliter of PPRV. No cross-reactivity was observed among the four probes or with other common pathogens of goats and sheep. The coefficient of variation (CV) values for inter-assay and intra-assay repeatability of each probe were both below 2% (intra-assay: 0.11% to 0.98%; inter-assay: 0.18% to 1.95%), demonstrating excellent repeatability. Testing of 62 clinical samples also confirmed that the method could effectively detect and differentiate clinical samples of different PPR lineages. This method, for the first time, enabled the differentiation of all PPRV lineages in a single reaction, improving the detection efficiency of the PPR virus and providing robust technical support for the global PPR eradication program. Full article

(This article belongs to the Collection Diseases of Small Ruminants)

► Show Figures

Figure 1

18 pages, 6275 KB

Open AccessReview

Respiratory Anatomy and Physiology of Reptiles

by Javier G. Nevarez

Animals 2026, 16(9), 1396; https://doi.org/10.3390/ani16091396 - 2 May 2026

Abstract

Reptiles have varied lung anatomy with three main lung types: unicameral, transitional, and multicameral. Crocodilians have a well-developed bronchial tree, while all other species have either a limited number of bronchi or no bronchi at all. The primary gas exchange structures are the [...] Read more.

Reptiles have varied lung anatomy with three main lung types: unicameral, transitional, and multicameral. Crocodilians have a well-developed bronchial tree, while all other species have either a limited number of bronchi or no bronchi at all. The primary gas exchange structures are the faveoli and ediculae, which can have either homogeneous or heterogeneous distribution within the lung parenchyma. The physiology of reptile respiration is also complex, varied, and at times contradictory across species. A basic understanding of anatomy and physiology is essential for proper diagnostic and therapeutic approaches to reptile patients. Therefore, a paradigm shift is needed to start thinking of the anatomy and physiology of individual species rather than believing that a single concept applies to all reptiles equally. As such, future research should aim to duplicate concepts across the more common species encountered in clinical practice. Full article

(This article belongs to the Special Issue Advances in Exotic Pet Medicine)

► Show Figures

Figure 1

Journal Description

Animals

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI