The skin, wool, milk and meat of sheep and goats can be processed for people to produce livestock products with important economic benefits and loved by the people, prompting the demand for sheep and goats continue to increase. Sheep and goats farming occupies an important position in China′s animal husbandry industry. Maintaining the superior performance of the breed, phenotypic breeding and genotypic breeding provide effective and accurate data support for scientific selection and breeding, and through the traditional and emerging technology means of breeding to improve the production performance of the breed, thus improving the production traits of sheep and goats to increase their economic benefits. Epigenetics is a sub-discipline of genetics and an emerging field of study, which is the regulation and genetic expression of genes without altering the DNA sequence. The application of high throughput sequencing technology for genetic breeding of sheep and goats continues to be enhanced at the DNA methylation, chromatin accessibility, histone modification and 3D genomic levels. It plays an important role in the study of complex economic traits in sheep and goats such as growth traits, fleece traits, reproductive traits, lipid metabolism, as well as immunity and disease, identifying relevant candidate genes, regulatory elements and their loci of action. This review summarizes the latest research status and future directions in the field of sheep and goats genetic breeding from an epigenetic perspective.

The domestic rabbit (Oryctolagus cuniculus) is one of the most widely utilized domesticated animals globally in economic, scientific research, and applied fields. In-depth exploration of rabbit genomic information holds significant importance for assessing genetic diversity, identifying functional genes, advancing breed genetic improvement, and conserving rabbit resources. This review synthesizes critical advancements in recent years regarding rabbit origin and domestication, genomic resources, comparative genomics, and functional genomics. It examines published nuclear and mitochondrial genome reference sequences of domestic rabbits and summarizes research progress on candidate genes linked to key economic traits, with the aim of providing references for genetic breeding efforts in domestic rabbits.

Semen cryopreservation technology is of great significance to prolong the storage time of semen of fine breed male animals, promote the development of artificial insemination technology of livestock, give full play to the breeding value of fine breed male animals, and further improve the production performance of livestock. However, due to oxidative stress caused by changes in the external environment during cryopreservation of sperm, the structure of sperm cells is damaged, and the effect of cryopreservation of semen is reduced. Therefore, the methods and evaluation indexes of semen cryopreservation were reviewed in this paper, and the components of semen cryopreservation diluent were analyzed to provide reference for the research and development of semen cryopreservation technology.

Pigeons have a long history of breeding, as monomorphic birds, their sex identification has always been an important issue in breeding and scientific research. In recent years, pigeon meat has become an important source of meat for people, leading to a rapid expansion of the pigeon breeding industry and scale, making sex identification as a major issue constraining the development of the pigeon breeding industry. This paper organizes and summarizes the sex determination mechanism, genetic basis of sex, and the current status of sex identification methods in pigeons, and discusses the main issues in pigeon sex identification. It clarifies the future research direction of pigeon sex identification in conjunction with current research progress, providing a reference for the sex identification of pigeons and birds.

Intestinal dysfunctions are the most obvious association with gut dysbiosis, and restoring the homeostasis of intestinal microorganisms is the key to the treatment of these diseases. Using probiotics for treating intestinal diseases has become an emerging therapeutic strategy. This paper reviews the recent application progress of probiotics in the treatment of intestinal diseases, probiotics in maintaining intestinal health and their potential action mechanisms, aiming to guide the application of probiotics in feed additives and therapeutic drugs, so as to treat related diseases and ensure the health and welfare of canine.

Parasitic diseases in livestock and poultry are one of the major threats to agriculture and public health worldwide. These diseases not only lead to reduced productivity in animals but can also be transmitted to humans through the food chain, posing serious public health risks. Therefore, accurate diagnosis of parasitic infections in livestock and poultry is of paramount importance, as it enables timely identification and control of diseases, minimizes economic losses, and protects human health. However, traditional diagnostic methods often suffer from limitations in sensitivity and specificity, restricting their application in early diagnosis and disease surveillance. In recent years, advances in nanotechnology and CRISPR gene-editing technology have provided new tools and approaches for the precise diagnosis of parasitic diseases in animals. Nanotechnology, particularly the use of nanomaterials with high surface area and unique optical and electrical properties, has shown great potential in biosensing and molecular diagnostics. CRISPR-based diagnostic technology, known for its accuracy and efficiency, has emerged as a powerful tool in gene function research and disease detection. The integration of these two technologies can lead to the development of more sensitive, specific, and rapid diagnostic methods to deal with the challenges posed by parasitic infections in livestock and poultry. This review will explore the application of nanotechnology and CRISPR-based diagnostic techniques in the accurate diagnosis of animal parasitic diseases. By investigating their potential and prospects, this work aims to support early diagnosis, vaccine development, and effective control strategies of livestock parasitic diseases, ultimately contributing to animal health and improved agricultural productivity.

Resveratrol (RSV) is a natural stilbene polyphenol compound that has various biological functions such as antioxidant, anti-inflammatory, antibacterial effect and improving the quality of livestock products. At present, RSV has been widely studied as a feed additive in monogastric animal production, but less research has been done on ruminants. This paper reviews the role of RSV in regulating ruminant production performance, product quality and health, with an aim to provide reference for the rational use of RSV in ruminant production.

Short chain fatty acids (SCFAs) refer to a class of saturated fatty acids with less than 6 carbon atoms on the carbon chain, also known as volatile fatty acids. SCFAs not only regulate lipid metabolism and reduce the risk of obesity, but also closely related to the physicochemical properties and nutritional functions of milk and dairy products. In this paper, the pretreatment technology, instrumental detection technology and conventional quantitative methods for the analysis of SCFAs are comprehensively reviewed, so as to provide a theoretical reference for the establishment of detection methods for SCFAs.

Mycotoxins are highly toxic metabolites produced by fungi. They can enter animals and humans through feed and food, leading to acute or chronic toxicity reactions, which pose serious health risks to both humans and animals. Traditional detoxification methods for mycotoxins, such as physical and chemical methods, often suffer from low efficiency and may result in the loss of nutritional components in feed or food. Laccase, a biocatalyst with broad catalytic activity, has been increasingly applied in the degradation of various compounds in recent years. Studies have shown that laccase can effectively degrade aflatoxin B₁ and zearalenone, exhibiting high degradation efficiency and producing safe degradation products. Therefore, applying laccase for the degradation of aflatoxin B₁ and zearalenone is an excellent choice. This paper summarizes the sources, structure, and catalytic characteristics of laccase, and reviews recent advances in the degradation of mycotoxins such as aflatoxin B₁ and zearalenone by laccase. Aiming to provide theoretical support and reference for the more efficient, safe, and environmentally friendly application of laccase in the field of mycotoxin degradation.

Cell penetrating peptide (CPP) is a kind of short peptide sequence consisting of 5~30 natural or artificial amino acid residues, which has the ability to enhance cell uptake of antigens and promote crossing various biological barriers. Because of its efficient and unique transmembrane transport ability, CPP has become a research hotspot in the biomedical field in recent years. Phage display technology (PDT) is a molecular technology to display on the surface of phage by genetic modification of phage DNA, which contains genetic sequences that can connect phenotypes with genotypes. This technology allows different peptide libraries to be expressed on the surface of phage particles, and can select peptides that specifically bind to targets, and it has the advantages of simplicity, high efficiency and low cost.Therefore, it can be used to realize targeted therapy without damaging other normal cells, which lays a foundation for developing new carriers for targeted drug delivery and realizing targeted drug delivery. In this paper, the research progress of cell penetrating peptides and screening cell penetrating peptides by phage display technology is reviewed, which also provides more effective ideas and methods for the research and development of feed antibiotic substitutes, and further provides new strategies and research directions for the precise killing of intracellular pathogens.

Ferroptosis is a form of programmed cell death initiated by iron overload, lipid peroxidation and plasma membrane damage. It is intimately associated with physiological processes such as iron homeostasis and the redox system within the organism. Inflammation is an essential physiological mechanism within the organism, facilitating defensive responses to various injurious stimuli. Recent studies have demonstrated that ferroptosis is closely related to the inflammatory response process, and that these two processes are not merely unidirectional. The promotion of inflammation by ferroptosis is facilitated by the release of damage-associated molecular patterns (DAMPs), lipid oxidation products and chemokine pathways. Conversely, inflammatory pathways (JAK/STAT, NF-κB, inflammasome, cGAS-STING and MAPK) activated during inflammation and secreted cytokines (TNF-α, IL-1β and IL-10) can also trigger cellular ferroptosis. This article focuses on the molecular mechanisms of ferroptosis, the common inflammatory pathways activated during the inflammatory response and the secreted cytokines. The interactions between ferroptosis and inflammatory responses and the regulatory mechanisms are also analyzed in detail, which offers insights into the development of novel therapeutic strategies for inflammatory diseases.

Porcine deltacoronavirus (PDCoV) is a novel porcine enteropathogenic coronavirus that causes watery diarrhea, vomiting, and dehydrating death in lactating piglets, resulting in significant economic losses to the swine industry. The development of effective vaccines and drugs has become an important strategy to prevent and control the PDCoV. The PDCoV genome encodes several types of proteins that play important roles in viral replication and host antiviral immunity, and the study of the proteins encoded by PDCoV is conducive to revealing the mechanism of viral invasion into the host. In this paper, the structural characteristics and specific functions of structural proteins, nonstructural proteins and accessory proteins encoded by PDCoV are summarized based on the latest literature advances at home and abroad, so as to provide reference for the development of anticoronaviral drugs and vaccines.

Coccidiosis is one of the common intestinal parasitic diseases in animals, seriously threatening animal production and the healthy development of the livestock industry, causing huge economic losses every year. In the past, the prevention and control of coccidiosis mainly relied on chemical drugs and immunization methods, but with the continuous increase of coccidia′s drug resistance and the continuous promotion of the "reduction and replacement of antibiotics" policy, plant extracts, as a green and efficient alternative to antibiotics, have attracted widespread attention. This review summarizes the common plant extracts with anticoccidial activity and the anticoccidial mechanisms of plant extracts, in addition, it elaborates on the shortcomings of plant extract research in the field of anti-coccidiosis. These results provide basic informations for the application of plant extracts in the prevention and control of coccidiosis. This review proposes that the application of plant extracts as functional feed additives for anti-coccidiosis is one of the main development directions in the future, which will lay a solid foundation for the healthy development of anti-coccidiosis plant extracts industry.

Although traditional Chinese veterinary medicine (TCVM) has demonstrated efficacy and safety in clinical veterinary practice, the molecular mechanisms underlying its anti-inflammatory effects are not fully understood. With the continuous advancement and widespread application of network pharmacology, using this discipline to predict the pharmacological basis and mechanisms of action of TCVM in treating related diseases has become a new trend in research. This review aims to systematically collate the research progress on the mechanisms of action of TCVM in treating inflammatory diseases based on network pharmacology methods. We collected relevant Chinese and English literature from the CNKI, Wanfang, VIP, PubMed and Web of Science databases, and analyzed the number of publications, authors, publishers and keywords of them using CiteSpace software. Besides, we summarized the commonly used databases of TCVM research and the main active ingredients, targets and related signaling pathways of TCVM that exert anti-inflammatory effects. Further elaborate the problems existing in the research of network pharmacology, and to prospect the application potential of it in the field of TCVM research. It is expected to provide a scientific basis and new insights for the modernization research of TCVM.

This study aimed to investigate the effects of the aldo-keto reductase family 1 member b1 (AKR1B1) gene on the proliferation and differentiation of porcine skeletal muscle satellite cells (PSCs). Bioinformatics tools were used to predict and analyze the structure and physicochemical properties of the AKR1B1-encoded protein. RNA was extracted from 8 tissues, including the duodenum, longissimus dorsi, and subcutaneous fat of 3-day-old piglets, and quantitative real-time PCR (qRT-PCR) was performed to determine AKR1B1 expression levels in each tissue. PSCs were isolated from leg muscles and longissimus dorsi and cultured in vitro, with samples collected at specific time points during proliferation and differentiation. Small interfering RNA (siRNA) was used to suppress AKR1B1 expression, and qRT-PCR, immunofluorescence, and Western blot analyses were conducted to evaluate AKR1B1′s role in PSCs proliferation and differentiation. The AKR1B1 protein consisted of 316 amino acids, was predominantly expressed in the cytoplasm, and was predicted to be a stable, highly hydrophilic, acidic protein. qRT-PCR results showed that AKR1B1 expression was highest in the longissimus dorsi and duodenum. During PSCs proliferation, AKR1B1 expression gradually increased, peaking on day 5 of differentiation before declining. Knockdown of AKR1B1 during proliferation significantly reduced the mRNA and protein levels of proliferation markers Ki67 and cyclin D1 (ccnd1) (P < 0.05) and decreased the proportion of EdU⁺ cells (P < 0.05). During differentiation, AKR1B1 knockdown significantly upregulated the mRNA and protein levels of differentiation markers myogenin (MyOG) and myosin heavy chain (MyH3) (P < 0.05). Immunofluorescence results showed a highly significant increase in the proportion of MyOG⁺ cells (P < 0.01) and an elevated differentiation index (P < 0.05). AKR1B1 knockdown significantly reduced the phosphorylation of AMPK at Ser182 (P < 0.05) while significantly increasing the phosphorylation of TSC2, RAPTOR, and mTOR at Ser2448 (P < 0.05). This led to a significant increase in the expression of S6K1 and S6 proteins (P < 0.05). In summary, AKR1B1 knockdown inhibited PSCs proliferation and positively regulated differentiation. AKR1B1 was found to mediate the AMPK/mTOR/S6 signaling pathway to regulate PSCs differentiation. This study provides insights into the specific effects of AKR1B1 on porcine skeletal muscle growth and development, offering a theoretical basis and scientific clues for healthy livestock management.

This study aimed to establish a detection method for MSTN gene-edited pigs based on recombinase polymerase amplification (RPA) and the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 12 (CRISPR/Cas12a)system, to meet the needs of nucleic acid testing and genotype identification in the research and breeding of gene-edited animals. Standard plasmids containing the porcine MSTN gene mutant sequence and wild-type sequence were constructed, with crRNAs targeting these standard plasmids designed. Detection systems integrating fluorescence reporter or colloidal gold test strip were established based on RPA and CRISPR/Cas12a technologies. Through systematic screening of crRNAs specifically recognizing the standard plasmids, optimization of reaction conditions, and evaluation of detection sensitivity, the method′s analytical performance was characterized. Ultimately, the accuracy and stability of this approach were validated by detecting porcine ear tissue samples. The results demonstrated that the method could specifically identify the 2 bp deletion and wild-type sequences of the MSTN gene. The fluorescence reporter system could detect as low as 4.1×10¹ copies·μL^-1 of the standard plasmid, while the colloidal gold test strip system could detect as low as 4.1×10³ copies·μL^-1. The accuracy and reliability of the system were validated by testing porcine ear tissue samples. The RPA-CRISPR/Cas12a detection method for MSTN gene-edited pigs established in this study is characterized by its simplicity, high specificity, and high sensitivity. It provides important technical support for the detection of MSTN gene-edited pigs and holds broad application prospects.

This study aimed to analyze the population structure and genetic diversity of the Meihuaxing pig to promote the effective conservation and utilization of its genetic resources. SNP typing was performed on 307 Meihuaxing pigs by using the 'Porcine 80K Functional Variants Genotyping Array', and the population genetic structure and runs of homozygosity (ROH) analyses were performed based on the SNP chip data. Principal component analysis (PCA) and population ancestry component analysis showed that there was obvious genetic stratification in the Meihuaxing pig resource population, and kinship based G matrix and clustering analysis further revealed that the studied population could be divided into 4 lineages. Some of these individuals were closely related, and the degree of inbreeding in family line 2 was relatively high, which requires reasonable selection measures to prevent inbreeding decline. A total of 18 442 ROHs were detected by ROH analysis, with an average length of 4.65 Mb. In addition, a total of 13 ROH islands were identified, and 164 genes were annotated. Further comparison of the ROH island regions of different family lines and functional annotation with literature and tissue expression profiles identified a number of genes associated with reproduction (RAB23, PRKD1, G2E3, etc.), growth (RUNX1T1, TMEM8B, NPR2, etc.), meat quality (DECR1, NFKBIA), carcass (PPP1R9A, PEG10), adaptability (DST, SLC26A7, IRF9), immunity (SIT1), feed efficiency (SLC2A2, PHKB, GPT2), disease (AKAP6) and other trait-related candidate genes.This study systematically analyzes the genetic structure of the Meihuaxing pig population and its ROH distribution at the genome-wide level, which lays the foundation for the in-depth analysis of the population characteristics of this excellent local pig breed, the genetic basis for the development of important traits, and the scientific conservation and utilization of the core population.

The aim was to distinguish between Taihang chickens and Bashang long-tailed chickens using a small number of SNPs by screening characteristic SNPs molecular markers. The whole genome resequencing data from 61 Taihang and 56 Bashang long-tailed chickens were used to extract important SNPs through linkage disequilibrium and population differentiation index analyses. Six machine learning classification models were adopted to predict individual categories and evaluate the model performance. The random forest model was used to evaluate the importance of SNPs, and the minimum number of SNPs were selected according to the accuracy, recall rate and AUC value. The effect was validated using principal component analysis, phylogenetic tree, and a genomic relationship matrix. A total of 28 SNPs were identified that effectively discriminate between Taihang and Bashang long-tailed chickens. The SNPs were primarily located in intergenic and intronic regions and were significantly enriched in the GO biological processes related to immunity, histone acetylation, metabolism as well as in the KEGG signaling pathway for base excision repair. Additionally, we identified genes associated with immunity (BCL11B, AvBD13, KAT7), lipid metabolism (URI1, RREB1, ZBTB20), and adaptability (ZNF536). The identified molecular marker combinations with integration of population genetics and machine learning techniques could distinguish Taihang and Bashang long-tailed chicken breeds. This study provides valuable insights for the development of "molecular identity cards" for local breeds, contributing to the conservation and identification of germplasm resources.

This study aimed to elucidate the synergistic interplay between rumen tissue morphogenesis and gene expression regulation in Hu sheep across distinct developmental stages, and to preliminarily explore the molecular basis underlying rumen functional maturation. Therefore, this study used healthy female Hu sheep and their female lambs as research subjects, which were divided into 4 groups according to the embryonic period (85±5 d), fetal period (125±5 d), neonatal period, and mature period (120±5 d), with 5 individuals in each group. After standardized feeding management, the lambs were euthanized by electroshock, and rumen dorsal sac tissues were collected. Part of the samples were fixed and stained for HE observation to analyze morphological differences; the remaining samples were frozen for RNA extraction and transcriptome sequencing to explore gene expression patterns. The results showed that although the thickness of the rumen wall gradually increased with age, the critical period for rumen papilla development occurred from the neonatal period to the mature stage. Transcriptome results also indicated that the rumen gene expression pattern at the mature stage was significantly different from that of the other 3 stages. The expression patterns of differentially expressed genes could be divided into 21 typical modules, among which some modules in the mature stage were mainly involved in biological processes and signaling pathways such as fatty acid metabolism, immune barrier construction, and mineral absorption. The expression level of the PIP gene in the rumen at maturity was significantly higher than that in the other 3 developmental stages, thereby regulating signaling pathways such as ErbB2 and MAPK to complete immune barrier construction. At the mature stage, the expression levels of solute carrier family members such as MCT1 were significantly upregulated, promoting the transmembrane transport of short-chain fatty acids and their metabolites, maintaining intracellular pH, and improving the molecular basis of nutrient transport. Therefore, the present study found that the key process of rumen maturation occurs after birth, and the transformation of gene expression pattern supports the maturation of rumen morphology, which provides a new way of thinking to reveal the molecular mechanism of rumen development in lambs.

This study aimed to provide an in-depth understanding of its population structure, which can explore the genetic variation and differentiation within populations and genetic differences between populations as well as geographic distribution characteristics, and provide an important basis for germplasm resource utilization and development of this breed. Ear tissues of 18 Wuxue goats (WXG), 9 Xiangdong Black goats (XDB), 9 Hechuan White goats (HCW), 9 Dazu Black goats (DZB), 11 Maguan Poll goat (MGG), and 10 Yunling goats (YLG) were collected and used for whole genome resequencing, with an average sequencing depth of about 10×. In this study, principal component analysis, phylogenetic analysis, population genetic structure analysis, heterozygosity analysis, population differentiation analysis, and linkage disequilibrium analysis were performed on 6 populations based on genome-wide data using GCTA, Plink, Admixture, Vcftools, and PopLDdecay software, respectively. The results of principal component analysis showed that Wuxue goats and Xiangdong Black goats were clustered into the same category, indicating that these two goat breeds have similar genetic backgrounds. In the phylogenetic analysis, Wuxue goats and other breeds of goat populations could be clustered into a single cluster, and were genetically closer to Xiangdong Black goats in the evolutionary tree. The results of the analysis of the genetic structure of the population showed that when the CV value was the smallest (K=3), Wuxue goats and Xiangdong Black goats had the same genetic components, indicating that the degree of genetic differentiation index between the two populations was small and the genetic backgrounds were similar. The results of heterozygosity analysis showed that Wuxue goats had lower nucleotide polymorphism (π), the lowest observed heterozygosity (Ho) and lower than the expected heterozygosity (He); ROH (runs of homozygosity) analyses showed that the number and length of ROHs in Wuxue goats were also significantly higher than those in other breeds, and the genomic inbreeding coefficient (F_ROH) was significantly higher than that of the other 5 populations, which suggests that there was a significant accumulation of purity fragments and a decrease in genetic diversity at the genomic level in Wuxue goats. The results of linkage disequilibrium analyses showed that Wuxue goats exhibited the highest degree of linkage disequilibrium, which further illustrated the low genetic diversity of the population. In conclusion, this study systematically analysed the genetic characteristics and population structure of the Wuxue goat, and found that the genetic background of Wuxue goats is similar to that of Xiangdong Black goats, and that the genetic diversity of their populations is low and there is a certain tendency of inbreeding, which suggests that we should pay attention to the expansion of the population size and the control of the inbreeding coefficient in the subsequent work of breeding conservation. These findings not only provide a scientific basis for the in-depth understanding of the genetic background, but also provide an important theoretical reference for the conservation and rational development and utilization of genetic resources of this breed.

This study aimed to analyze the expression profiles of long non-coding RNAs (lncRNAs) in bovine muscle tissues during embryonic development, with the goal of identifying lncRNAs potentially involved in muscle development. Transcriptome sequencing was conducted on muscle tissue samples from 3 developmental stages (3-month-old fetuses, 6-month-old fetuses, and 9-month-old newborns obtained from genetically homogeneous Japanese Black cattle using embryo splitting techniques). Differential expression analysis was performed on the identified lncRNAs to screen key lncRNAs involved in embryonic muscle development. Subsequent bioinformatic analyses were carried out to predict the functions and target genes of these lncRNAs. Sequencing data revealed 9 913 differentially expressed lncRNAs and 3 079 differentially expressed mRNA transcripts across the developmental stages. Clustering analysis indicated that the highest number of differentially expressed lncRNAs and mRNAs occurred in the 3-month-old fetal muscle tissue. By identifying protein-coding genes located within 10 kb upstream or downstream of the differentially expressed lncRNAs, 2 064 cis-regulated target genes were predicted. A Venn diagram analysis comparing these target genes with the differentially expressed mRNAs identified 448 overlapping genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of these overlapping genes highlighted 99 lncRNAs and 27 candidate target mRNAs closely associated with muscle development. Short time-series expression miner (STEM) analysis of expression data revealed that both lncRNAs and mRNAs clustered into a significant profile characterized by an initial increase followed by a decrease in expression levels, encompassing 68 lncRNAs and 12 mRNAs. Finally, a regulatory network was constructed using Cytoscape based on cis-regulatory relationships based on the 68 lncRNAs and 12 mRNAs, suggesting that the majority of these lncRNAs may regulate genes such as SERP1, FXR1, and DVL3. The results showed that the 3-month-old period may be a critical period for bovine muscle development, and the 68 lncRNAs screened may affect the expression of corresponding target genes through competitive adsorption of corresponding miRNAs, thereby playing a regulatory role in the growth and development of bovine skeletal muscles at different stages.

Obtaining high-quality tenogenic mesenchymal stem cells(MSCs) through in vitro culture, providing seed cells for the treatment of sports injuries (including equine athletic injuries), various diseases, single-cell sequencing, multi-omics research, genomic library construction, cDNA library construction, mitochondrial DNA library construction, gene function research and other investigations, had important in-depth research value. In this study, tendon tissues were collected from the skeletal muscles of 63 healthy male Peking duck embryos at 26 days of age (average weight: 40.3 g). Tenogenic MSCs were isolated and cultured in vitro using the type Ⅳ collagenase digestion method and the tissue block adhesion culture methods. Meanwhile, comprehensive quality assessment of the cultured cells in vitro were conducted according to international cell quality inspection standards and parameters. The results of 20 quality tests, including cellular morphology, pre-cryopreservation viability, microbial contamination (bacteria, fungi, protozoa, mycoplasma, viruses), positive marker expression, clonogenic capacity, migration ability, post-thaw morphology, post-thaw viability, growth curve analysis, population doubling time, reverse transcription PCR (RT-PCR) for surface markers, immunohistochemistry, karyotype analysis, and multidirectional differentiation potential (adirogenic, osteogenic, and chondrogenic induction), indicated that all established cell lines met international standarda for high-quality cells. Through a large number of repeated experiments, a scientific system for the culture of tenogenic MSCs in vitro for sports injuries therapy has been established, and a substantial quantity of high-quality donor cells has been acquired. This achievement lays a solid theoretical, methodological, technical, and material foundation for successfully constructing medical models for sports injury treatment, as well as for related research in zoology, animal science, veterinary medicine, and the broader life sciences.

This study aimed to investigate the effect of betaine on the in vitro developmental ability of porcine parthenogenetic embryos. Porcine ovaries were collected from a local slaughterhouse. Cumulus-oocyte complexes were aspirated and selected. After in vitro maturation and parthenogenetic activation, the activated embryos were subjected to betaine treatment at a range concentrations (0, 0.25, 0.5, and 1.0 mmol·L^-1) during in vitro culture. The cleavage and blastocyst formation rates were recorded at 48 h and 168 h, respectively, in order to determine the optimal concentration of betaine. Hoechst 33342 staining was conducted to calculate the total cell number of blastocyst. The expression levels of pluripotency-related genes (OCT4, NANOG, and SOX2) in blastocysts were analyzed by RT-qPCR. Reactive oxygen species (ROS) and glutathione (GSH) levels in blastocysts were measured. m⁶A methylation levels in embryos at the 2-cell, 4-cell, 8-cell, morula, and blastocyst stages were measured by immunofluorescence staining. The expressions of genes encoding m⁶A methyltransferases and demethylases were also examined. All the experiments were repeated at least 3 times. The results showed that the blastocyst rates after parthenogenetic activation in the 0.25 and 0.5 mmol·L^-1 betaine groups were significantly higher than those of the control group and 1.0 mmol·L^-1 group (P < 0.05), with the highest blastocyst rate in the 0.5 mmol·L^-1 group. Compared with the control group, the 0.5 mmol·L^-1 treatment group showed a significant increase in the total blastocyst cell number (P < 0.01), upregulated expressions of OCT4, NANOG, and SOX2 associated with pluripotency (P < 0.05), decreased ROS levels (P < 0.01), and increased GSH levels (P < 0.000 1). Following 0.5 mmol·L^-1 betaine exposure, the m⁶A methylation levels and the expressions of m⁶A methyltransferase-related genes (WTAP, METTL3, and METTL14) in embryos at the 8-cell, morula, and blastocyst stages were significantly higher than those in the control group (P < 0.05). However, the expressions of m⁶A demethylase-related genes (ALKBH5 and FTO) were not significantly affected. In conclusion, enriching the in vitro culture medium with 0.5 mmol·L^-1 betaine improved the in vitro developmental competence and embryonic quality of porcine parthenogenetic embryos. The protective effects of betaine on embryonic development may be attained through the combine mechanisms of its anti-oxidative capacity and enhancement of m⁶A modification ability.

This study aimed to investigate the effects of selenium (Se, from sodium selenite) on the autophagy of ram leydig cells (LCs) and its underlying mechanism. In this study, the LCs collected from 3 healthy Dorper Hu crossbred ram aged 8 months were isolated and treated with different concentrations of Se (0, 2, 4 and 8 μmol·L^-1) for 18 h. The experiment was repeated 3 times and each treatment group included 6 replicates. The proliferation of LCs was detected by CCK-8 assay, autophagy level was detected by MDC, the expression of autophagy-related genes (ATG5, P62 and LC3) and key molecules of PI3K/AKT/FoxO1 signaling pathway were detected by qRT-PCR and Western blot. The AKT activator SC79 or FoxO1 siRNA were used to examine the mechanism of PI3K/AKT/FoxO1 pathway in excessive Se (8 μmol·L^-1) regulating the autophagy of LCs. The results showed that the highest and lowest (P < 0.05) cell viability was obtained in the 2 μmol·L^-1 and 8 μmol·L^-1 group, respectively. The ROS level in the 2 μmol·L^-1 group was significantly (P < 0.05) lower than those in other groups. The 8 μmol·L^-1 group had the highest (P < 0.05) autophagy level of LCs. Excessive Se (8 μmol·L^-1) induced ROS accumulation and significantly (P < 0.05) increased the expressions of ATG5 and LC3-Ⅱ/Ⅰ, and significantly (P < 0.05) decreased the expression of P62. Compared with the control group, the 8 μmol·L^-1 group significantly inhibited (P < 0.05) the activities of PI3K and p-Akt, significantly increased (P < 0.05) the expression of FoxO1 in nucleus and total, significantly reduced the abundance of p-FoxO1 (P < 0.05). In order to further investigate the role of PI3K/AKT/FoxO1 pathway in excessive Se-induced autophagy of LCs, the abundance of LC3-Ⅱ/Ⅰ ratio and ATG5 proteins significantly decreased (P < 0.05) after the cells were pre-treated with SC79 (15 mg·L^-1) for 1 h or the FoxO1 was downregulated by siRNA. P62 significantly (P < 0.05) upregulated the autophagy induced by excessive Se. The SC79 significantly (P < 0.05) inhibited the dephosphorylation of FoxO1 induced by excessive Se and reduce nuclear translocations. In summary, excessive Se (8 μmol·L^-1) regulates the phosphorylation of FoxO1 and its nuclear translocation by inhibiting PI3K/AKT pathway, inducing oxidative stress and autophagy of sheep leydig cells. The results provide some experimental evidences for elucidating the molecular mechanism of the negative effects caused by excessive Se in LCs.

The aim of this study was to investigate the effect of dietary rumen-protected fat (RPF) addition on growth performance, serum biochemistry, slaughter performance and meat quality of fattening yaks. Twenty-four male yaks with similar body weight (275.63±9.84 kg) were randomly assigned to three treatment groups (8 in each group) and were fed basal diet (CON), basal diet with 1.5% RPF (RPF 1.5) supplementation, and basal diet with 3.0% RPF (RPF 3.0) supplementation, respectively. The experimental period was 90 d. All yaks were weighed at the beginning and the end of the experimental period, blood samples were collected from the jugular vein of yaks before morning feeding on the last trial day to analyse the differences in blood biochemistry and hormone secretion. Three yaks from each group were selected to determine the slaughter performance including carcass characteristics, and the longissimus dorsi muscle were collected for meat quality analysis. The results showed no significant impact of RPF supplementation on the feed intake, the average daily weight gain of fattening yaks was significantly increased by RPF addition, the average daily weight gain of yaks in the RPF3.0 group reached 900.69 g ·d^-1 which reduced the feed to gain ration significantly as well (P < 0.05). Blood urea nitrogen concentration in PRF groups were significantly higher than that in CON group (P < 0.05). Serum lipid metabolites triglycerides, cholesterol, and non-esterified fatty acids were significantly increased in the RPF 3.0 group (P < 0.05), and the lipid transport molecules very low-density lipoprotein and apolipoprotein B100 were significantly elevated in the serum of RPF1.5 and RPF3.0 yaks (P < 0.05). Dietary supplementation with 1.5% and 3.0% RPF significantly increased serum insulin and leptin secretion levels in fattening yaks (P < 0.05). The carcass traits were higher in the RPF1.5 and RPF 3.0 groups than those in the CON group, but did not reach a significant level. The yak carcass weight, and net meat weight in RPF 1.5 group as well as ribeye area, carcass weight, net meat weight, dressing percentage and net meat percentage in RPF 3.0 group were significantly higher (P < 0.05) than those of the CON group. The RPF 3.0 treatment significantly increased the cooked meat percentage of the longissimus dorsi muscle compared to the CON group (P < 0.05), meanwhile significantly decreased the muscle shear force (P < 0.05). In conclusion, under the condition of the current experiment, dietary supplementation of RPF can enhance the growth performance of fattening yaks, and improve slaughter performance and meat quality by promoting regulation hormone secretion and lipid metabolism.

The aim of this study was to investigate the effects of different milking time on colostrum quality and the effects of colostrum quality on passive immunity and serum biochemical parameters of newborn calves. According to the time interval between delivery and milking, 329 cows on verge of delivery and at the second parity with good body condition were divided into four groups: Milking within 2 h after delivery, milking 2~4 h after delivery, milking 4~8 h after delivery and milking more than 8~12 h after delivery. The effect of different milking time after delivery on the content of immunoglobulin G (IgG) in colostrum was determined. Forty-five Holstein female calves (38 ±2 kg) with similar birth date were selected and randomly divided into three groups: High quality colostrum group, medium colostrum group and low quality colostrum group, with 15 calves in each group. Calves were fed with three different quality colostrum using the 4+2 feeding mode (4 L colostrum was given within 2 h after birth and 2 L colostrum was given 6 h after birth). The levels of IgG in colostrum were 63.8, 37.6 and 15.6 mg ·mL^-1, respectively. Blood samples were collected from all calves after birth(0 h), 24 h and 48 h after colostrum feeding (within 2 h after birth), and the contents of total protein (TP), IgG, albumin (ALB), C3 and C4 in serum were analysed. The results showed that: 1) The IgG content of colostrum milked within 2 h after delivery was significantly higher than that of colostrum milked at 2~4 h, 4~8 h and more than 8 h after delivery (P < 0.01). 2) There was no significant difference in serum TP and IgG content among the three groups before colostrum was fed. At 24 h and 48 h after colostrum was fed, the serum TP and IgG content of the high quality colostrum group were significantly higher than those of the medium colostrum group and the low quality colostrum group (P < 0.01). 3) The average serum IgG content at 24 h and 48 h in high quality colostrum group and medium colostrum group were more than 10 mg ·mL^-1 (the minimum IgG content for successful passive immunity of calves). In low quality colostrum group, the serum IgG content of 5 calves was less than 10 mg ·mL^-1 at 24 h, accounting for 33.3% of calves in this group, and the serum IgG content of 4 calves was less than 10 mg ·mL^-1 at 48 h, accounting for 26.7% of calves in this group. In conclusion, the shorter milking interval after delivery, the higher the quality of colostrum, and the highest content of IgG in colostrum was found when the milking interval was controlled within 2 h. High quality colostrum contributes to the successful passive immunity of newborn calves and has beneficial effects on serum biochemical parameters.

This study aims to systematically evaluate the effects of adding essential oils (EOs) to the diet on serum immune and biochemical indicators in suckling calves. A Meta-analysis was conducted by screening 537 published studies up until April 2024, with 17 studies involving and a total of 711 samples being included. A random effects model (REM) was used to calculate combined statistical measures, and subgroup analysis, sensitivity analysis, and publication bias analysis were also performed. The Meta-analysis results showed that adding EOs to the diet significantly increased the concentrations of immunoglobulin A (IgA) (SMD=0.66, 95% CI: 0.23-1.08, P < 0.002), immunoglobulin G (IgG) (SMD=0.70, 95% CI: 0.37-1.02, P < 0.001), and triglycerides (TG) (SMD=0.51, 95% CI: 0.10-0.92, P=0.01) in the serum of suckling calves. EOs also significantly increased the concentrations of immunoglobulin M (IgM) (SMD=0.49, 95% CI: 0.03-0.96, P=0.04) and total protein (TP) (SMD=0.45, 95% CI: 0.03-0.87, P=0.04), and significantly reduced the concentration of total cholesterol (TC) (SMD=-0.59, 95% CI: -1.07 to -0.11, P=0.02). Subgroup analysis, comparing effectiveness and stability, indicated that short-term feeding (≤56 days) of EOs is more effective than long-term feeding (>56 days), and adding EOs via solid feed (SF) is more effective than via liquid feed (LF). Sensitivity analysis and publication bias analysis confirmed the stability and reliability of the results. In conclusion, this study establishes a theoretical foundation for the application of EOs in calf production through Meta-analysis, demonstrating that adding EOs to the diet can effectively improve serum immune and biochemical indicators in suckling calves.

This study was conducted to investigate the effects of 6 drying methods on the determination of amino acid digestibility (AAD) and its additivity in pig feed by using the bionic digestion method, in order to provide a reference for the establishment of rapid evaluation method for the amino acid efficacy of feeds. Randomized block design was employed in this experiment. Five experimental diets, including 4 commonly used feed ingredients for pigs: corn, wheat, soybean meal, and wheat bran, and a complete diet formulated with the above 4 ingredients, were digested in simulated digestion system (SDS-Ⅲ). The residues from the in vitro digestion were dried by using 6 drying methods: Treatment 1 (Trt1): Air drying at 55 ℃ with concurrent moisture measurement; Treatment 2 (Trt2): Air drying at 55 ℃ followed by oven drying at 105℃; Treatment 3 (Trt3): Air drying at 65 ℃ with concurrent moisture measurement; Treatment 4 (Trt4): Air drying at 65 ℃ followed by oven drying at 105℃; Treatment 5 (Trt5): Air drying at 65 ℃ (add 2 mL 1 mol·L^－1 HCl) followed by oven drying at 105℃; Treatment 6 (Trt6): Freeze drying. Samples dried by different methods were weighed, the amino acid contents were determined, and dry matter digestibility (DMD) and AAD were calculated. The values were corrected to the true digestibility levels using endogenous losses measured with nitrogen-free diet. Each treatment had 5 replicates per diet, with 1 digestion tube per replicate. The results showed that: 1) There were no significant differences in DMD of corn, wheat, and complete diet among the 6 drying methods (P>0.05). However, the DMD of soybean meal in Trt6 was greater compared to Trt2, Trt4, and Trt5 (P < 0.05), the DMD of wheat bran in Trt3, Trt5 were greater than the other 3 treatments (P < 0.05); 2) On soybean meal and complete diet, no significant difference was observed in AAD among the 6 drying methods (P>0.05). On corn, the AAD in Trt3, Trt6 was lower than that in Trt5 (P < 0.05). On wheat, the AAD in Trt1 and Trt3 were greater than other 4 treatments (P < 0.05). On wheat bran, the AAD in Trt3, Trt4 and Trt5 were greater than other 3 treatments (P < 0.05). Additionally, the analysis results taken the test samples as block group showed that, there was no significant difference in AAD among the 6 drying methods (P>0.05). 3) The relative deviations between the calculated and determined values of digestible amino acid content in the complete diet were less than 5% for Trt2 and Trt6, and the slopes were not significantly different from Y=X (P>0.05). In conclusion, when evaluating the AAD of pig feeds using the biomimetic digestion method, the drying method of air drying at 55 ℃ followed by oven drying at 105℃ to treat the digestion residues is similar to freeze drying, and exhibits good additivity.

The study aimed to investigate the effects of glucosamine (GlcN) on serum antioxidant and inflammatory indexes and intestinal microbiota in weaned piglets. A total of 250 healthy 21-day-old weaned "Duroc×Landrace×Yorkshire" piglets, with similar body weights, were randomly allocated into five treatment groups. Each group consisted of five replicates with ten piglets per replicate. The trial duration was 14 days. The piglets were fed with the following diets: basal diet (NC group), basal diet + 75 mg·kg^-1 chlortetracycline (PC group), basal diet + 1 g·kg^-1 g GlcN (G1 group), basal diet + 2 g·kg^-1 GlcN (G2 group), and basal diet + 3 g·kg^-1 GlcN (G3 group). At the end of the 14-day trial, two replicates were randomly selected from each group to collect serum and fecal samples. These samples were then subjected to assessments of serum oxidative stress and inflammation-related biomarkers, analysis of fecal microbiota composition, and correlation analysis between serum indicators and microbial composition. The results indicated that: 1) GlcN supplementation can change serum oxidative stress-related index MDA (malondialdehyde), T-AOC (total antioxidant capacity), CAT (catalase), T-SOD (total superoxide dismutase) and index of immune function IL-10 (interleukin-10) and IL-1β (interleukin-1beta). 2) GlcN supplementation can influence intestinal microbial flora. At the phylum level, the top three most abundant bacterial phyla were Firmicutes, Bacteroidota, and Spirochaetota. At the genus level, compared to the NC group, the abundance of Ruminococcaceae UCG-002 was significantly reduced and showed a significant negative correlation with T-SOD (P < 0.05) in the G2 group, the abundance of norank_f_Eubacterium_coprostanoligenes_group was reduced in the G3 group (P < 0.05). The abundance of norank_f_Ruminococcaceae increased in the G1 group (P < 0.05). Specifically, Lachnospiraceae Dorea in the G2 group showed a significant positive correlation with T-SOD, whereas in the G3 group, it exhibited a significant negative correlation with IL-6 (P < 0.05). Additionally, Christensenellaceae_R-7_group was negatively correlated with TNF-α (tumor necrosis factor-α) in the G2 group (P < 0.05), while it displayed a significant positive correlation with T-SOD in the G3 group (P < 0.05). After GlcN supplementation, three genera including UCG-002, Dorea and Christensenellaceae_R-7_group in piglet intestine were closely related to both antioxidant and anti-inflammatory indexes. In summary, GlcN can enhance the antioxidant capacity and immune function, and regulate intestinal microbiota together to alleviate weaning stress in piglets.

The aim of this experiment is to investigate the improvement effect and mechanism of Lycium barbarum flavonoids (LBFs) on the muscle quality of meat ducks. Two hundred one-day-old male Cherry Valley ducks were randomly divided into four groups, with six replicates per group and ten ducks per replicate. The control group was fed a basal diet, while the experimental groups were fed the basal diet supplemented with 250, 500, or 1 000 mg ·kg^-1 of LBFs for 42 days. After slaughter, the quality of the breast muscle, intramuscular fat content, ROS levels, and antioxidant capacity were measured. The results showed that, regarding meat quality, compared with the control group, dietary 500 and 1 000 mg ·kg^-1 of LBFs significantly reduced cooking loss, drip loss after 24 hours post-slaughter, shear force values, improved meat color (redness), and increased pH_{24 h} (P < 0.05) in the breast muscles of ducks. Dietary 500 mg ·kg^-1 of LBFs had no sigaificant effect on the relative area of lipid droplets or the triglyceride content in the breast muscle (P>0.05). In terms of antioxidant function, compared with the control group, dietary 500 and 1 000 mg ·kg^-1 of LBFs significantly increased the activities of glutathione peroxidase (GSH-Px) and total superoxide dismutase (T-SOD), or decreased reactive oxygen species (ROS) and malondialdehyde (MDA) contents (P < 0.05) in the breast muscles. There were no significant differences in catalase (CAT), total antioxidant capacity (T-AOC), and glutathione (GSH) contents among the groups (P>0.05). Dietary 500 mg ·kg^-1 of LBFs significantly reduced the fluorescence intensity of ROS (P < 0.05) in the breast muscles. Dietary 500 and 1, 000 mg ·kg^-1 of LBFs significantly increased the relative mRNA expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 1 (SOD1), and heme oxygenase-1 (HO-1), and 500 mg ·kg^-1 of LBFs also significantly increased the relative mRNA expression level of NAD(P)H quinone oxidoreductase 1 (NQO1) (P < 0.05) in the breast muscles. There were no significant differences in the relative mRNA expression levels of CAT or GSH-Px among the groups (P>0.05). Dietary 500 and 1 000 mg ·kg^-1 of LBFs significantly increased the relative protein expression levels of Nrf2 and HO-1, and decreased the relative protein expression level of Kelch-like ECH-associated protein 1 (Keap1) (P < 0.05) in the breast muscles. In conclusion, dietary LBFs can improve duck meat quality by enhancing muscle water-holding capacity and pH, improving meat color, and reducing shear force. This improvement is likely closely related to the activation of the Nrf2/HO-1 signaling pathway, thereby enhancing antioxidant function. Under the conditions of this experiment, an appropriate level of LBFs supplementation is 500 mg ·kg^-1.

This study aimed to study the biological characteristics and the immunoprotective effect of DEV vaccine strain with UL35 gene deletion. A UL35 gene-deletion virus strain was constructed based on the bacterial artificial chromosome (BAC) clone pDEV-EF1 which carries DEV vaccine strain full-length genome. The BAC clone pDEV-ΔVP26 of UL35 gene deletion was generated by two-step Red/ET recombination in E. coli. The recombinant virus rDEV-ΔVP26 was rescued from chicken embryo fibroblasts (CEFs) by calcium phosphate precipitation. And then the biological characteristics and immunoprotective capacity of recombinant virus were evaluated. Growth curves show that the virus titer of rDEV-ΔVP26 was stable increasing from 24 to 84 h, up to the peak value 10^5.36 TCID₅₀·0.1 mL^-1. During this period, the titer of rDEV-ΔVP26 was slightly reduced compared to the parental strain rDEV-EF1, and the plaque size of rDEV-ΔVP26 was decreased 10.60% compared to the parental virus. Animal experiments showed that 10⁶ TCID₅₀ rDEV-ΔVP26 is safe to 30-day-old ducks, and pre-immune ducks with 10⁵ TCID₅₀ rDEV-ΔVP26 could completely protect ducks from high virulent DEV challenge, this is similar to the rDEV-EF1 control group. The results showed that UL35 was non-essential gene of DEV, and absence of UL35 did not affect the immune protection capacity of DEV vaccine strain. These studies have laid a foundation for developing differential diagnosis vaccine between infected and vaccinated animals.

Newcastle disease is an acute contact infectious disease caused by Newcastle disease virus (NDV), which is characterized by respiratory and digestive symptoms. The widespread epidemic of NDV has caused huge economic losses to the poultry industry. NP is a nucleocapsid protein of NDV, which plays an important role in viral replication, immune response and cellular autophagy, while the host proteins interacting with NP remains unclear. The study was aim to screen the host proteins interacting with NDV NP and explore the effects of the host proteins on the replication of NDV, as well as to provide a theoretical basis for disease-resistant drug development. The eukaryotic expression plasmid of NDV NP was successfully constructed with the eukaryotic expression vector pXJ40. The host proteins interacting with NDV NP were screened by co-immunoprecipitation, mass spectrometry, GST-pull down, and laser confocal microscopy. The effects of the host proteins on NDV replication were explored by overexpression and knockdown in DF1cells. A total of 211 potential host proteins interacting with NP were screened by mass spectrometry. Enrichment analysis of the differential proteins revealed their possible biological functions and involvement in biological processes. Further detailed analysis of the interaction between HSP70 and NP confirmed the direct interaction of the two proteins and mapped the domain responsible for this binding to the SBD region in HSP70. NDV infection down-regulates HSP70 expression in host cells. Overexpression of HSP70 significantly inhibited viral replication at both the protein and transcriptional levels. However, both knockdown of endogenous HSP70 and use of HSP70 inhibitors significantly promoted NDV replication. This study indicated that the host protein HSP70 interacts with NDV NP and the overexpression of HSP70 could significantly inhibit NDV replication and act as a negative regulator of NDV infection, which provided a new idea for the design of antiviral drug targeting HSP70.

To evaluate the protective efficacy of the attenuated vaccine against subtype B avian metapneumovirus on commercial layer chickens, the attenuated vaccine against subtype B avian metapneumovirus (LN16-A strain) prepared in the laboratory was used to immunize 21-day-old commercial layer chickens by intranasal administration at a dose of 400 TCID₅₀/chicken. Samples were collected on 7, 14, and 21 days post-immunization to separate the serum and measure the ELISA antibody and neutralizing antibody titers. At 21 days after immunization, the results showed the positive rate of ELISA antibody was 90% and the average neutralizing antibody titer was 7.51 log2 in the immunization group. At 21 days post-immunization, the commercial layer chickens were attacked by subtype B avian metapneumovirus (LN16-V strain) at a dose of 5 000 TCID₅₀ per chicken. The results indicated that chickens in the challenge control group had cloudy or viscous nose with an 80% incidence rate, while chickens in the immune group showed no clinical symptoms. RT-qPCR was used to measure virus copies in palatine swabs collected from chickens in each group from 1 to 7 days. The results showed that the viral loads in the immune group decreased by 175 folds compared with that in the challenge control group. And the histopathological examination results showed that varying degrees of pathological damage in tissues such as the turbinate bone and trachea of chickens were found in the challenge control group, while no obvious pathological changes of chickens were found in the immune group. The above results indicate that the attenuated vaccine against subtype B avian metapneumovirus (LN16-A strain) can provide protection for commercial layer chickens. And this study further provides a theoretical basis for controlling the prevalence of subtype B avian metapneumovirus in layer flocks and formulating an immunization program to prevent subtype B avian metapneumovirus disease.

In order to systematically evaluate whether the biological characteristics of infectious bronchitis virus (IBV) M41 strain will change after serial passages, we continuously passaged the IBV M41 strain (CVCC AV1511, abbreviated as AV1511-1979) introduced from France by the National Center for Veterinary Culture Collection in 1979 on SPF chickens for five times to evaluate its differences in genome variation, virus shedding, and tissue tropism. Illumina high-throughput sequencing method was used to sequence the genome sequences before and after passage, and an IBV challenge model was established. RT-PCR, RT-qPCR and tracheal ring cilia swing test were used to evaluate the differences before and after passage in tems of virus content, clinical symptom observation and tissue tropism. The results showed that the whole genome of the AV1511-1979 strain did not mutate after 5 generations of continuous passage on SPF chickens, but it was quite different from Mass strains from other sources in 1ab, 5a, 4b and N protein regions. In the virus challenge model, the inoculated chickens showed obvious clinical symptoms such as depression, mouth breathing and respiratory rales. The ciliary activity of the tracheal ring was examined by autopsy, and it was found that the ciliary activity was poor or stopped. The results of RT-qPCR showed that the virus could be replicated in the trachea, lung, kidney, glandular stomach, duodenum and cecal tonsil of infected chickens, especially in the trachea, kidney and glandular stomach. There was no significant difference in viral load before and after passage. The results showed that the biological characteristics of the IBV M41 strain, AV1511-1979, were stable and did not change within 5 generations on SPF chickens. As a standard virulent strain for the production of IBV inactivated vaccine and IBV vaccine testing, our work provides a reference for the generation control of production viruses and vaccine evaluation.

Clostridium perfringens is an important pathogen that endangers the deer breeding industry. In this study, a strain of Clostridium perfringens was isolated from clinical samples obtained from deer using selective identification media. The strain was identified through 16S rRNA sequencing, toxin-type polymerase chain reaction (PCR), and biochemical assays. An analysis of antimicrobial resistance was also performed. To establish a murine infection model, mice were subjected to intraperitoneal injection with the isolated strain, and subsequent observations were made regarding incidence rates, mortality, and histopathological alterations. The findings indicated that the isolated strain was identified as Clostridium perfringens type A, aligning with the biochemical characteristics of Clostridium perfringens. Furthermore, this strain exhibited resistance to the antibiotics amikacin, polymyxin B, streptomycin, kanamycin, clindamycin, and cotrimoxazole. The mice of the experimental group exhibited poor vitality, characterized by unkempt fur and reduced mobility. Examination revealed hepatosplenomegaly, thinning of the intestinal wall, and the presence of yellow material within the small intestine. The median lethal dose was determined to be 7.99×10⁷ CFU·mL^-1. Histopathological analysis indicated hyperemia and hemorrhage across various tissues and organs, infiltration of inflammatory cells, partial villous atrophy and loss in the small intestine, and structural disintegration.

Foot-and-mouth disease(FMD)caused by foot-and-mouth disease virus (FMDV) is a high infectious disease of pigs, cattle, sheep and other major livestock. In order to develop new strategies against FMDV to carry out comprehensive prevention and control of the disease, the heavy chain variable region (VH) sequences and light chain variable region (VL) sequences of 5 different IgA antibodies against type O and A FMDV were screened from the specific porcine BCR library of type O and A FMDV and linked with the gene sequences of the heavy chain constant region and the light chain (Kappa chain) constant region of porcine IgA, then, five heavy chain plasmids and five light chain plasmids were respectively constructed. The corresponding heavy chain plasmids and light chain plasmids were co-transfected into CHO-s suspension cells, after 7 days post transfection, the transfected supernatants were collected for antibody purification. The purified antibodies were identified by SDS-PAGE and Western blot. The ability of the five antibodies neutralizing types O and A FMDV was analyzed by virus neutralization test. The reactivity of the five antibodies with FMDV was detected by ELISA. Results showed that 5 IgA antibodies were successfully expressed in CHO-s cells and they all could not neutralize type O and A FMDV, but one of them (POA-A8) had the strongest ability to specifically bind with FMDV, which could be used for establishment of FMDV diagnostic methods in the future. This study lays a foundation for research of anti-FMDV nonneutralizing sIgA antibodies and development of diagnostic methods for FMDV in the future.

This study aimed to utilize a mutant library of Mycobacterium tuberculosis variant (M. tuberculosis var.) bovis C68001 for high-throughput screening to identify key genes affecting biofilm formation. The mutant library of M. tuberculosis var. bovis C68001 was cultured in Sauton′s medium to select mutants with significant differences in biofilm phenotype. The location of mutated genes was determined by resistance marker rescue and sequencing, and the impact of these mutated genes on the antioxidant capacity and SDS resistance of the bacteria was assessed. Furthermore, a phage system was employed to construct strains with target gene deletion, complementation, and overexpression. The effects of the target genes on bacterial mycelium were investigated using scanning electron microscopy, and their influence on bacterial stress resistance and intracellular survival was evaluated by measuring the bacteria′s acid resistance, antioxidant capacity, SDS resistance, and survival within the J774A.1 mouse macrophage cell line. The study successfully screened eight biofilm-deficient strains from the mutant library, with four identified as single-insertion mutants. The mutated genes were Rv1096, Rv3425, Rv3136, and Rv3671c. Knockout, complementation, and overexpression strains of the Rv3671c gene were constructed and verified by PCR and Western blot. These strains exhibited enhanced abilities in biofilm formation, SDS resistance, and intracellular survival. The Rv3671c gene plays a crucial role in the biofilm formation and stress resistance of M. tuberculosis var. bovis C68001. The constructed mutant library of M. tuberculosis var. bovis C68001 provides an efficient tool for target gene screening and identification, offering a reliable approach for exploring the genetic functions of M. tuberculosis var. bovis C68001.

This study aimed to investigate the in vivo pharmacokinetics of thiamphenicol powder in chickens after oral administration. After the pharmacokinetic parameters were obtained, the rationality of the recommended oral dosing regimen of thiamphenicol powder in chickens was revaluated by Monte Carlo simulation (MCS). Three groups were set: thiamphenicol 10 mg·kg^-1 BW intravenous injection group, and thiamphenicol powder 10 and 20 mg·kg^-1 BW oral gavage groups. Blood samples were collected at a scheduled time and the concentration of thiamphenicol in chicken plasma was determined by a verified HPLC method. The pharmacokinetic parameters of thiamphenicol in chickens were fitted, and the epidemiological cut-off value (ECOFF) of thiamphenicol against Pasteurella multocida was established. Then the PK/PD cut-off values at bacteriostatic, bactericidal, and eradication of thiamphenicol against Pasteurella multocida were used to predicate the target attainment rate (TAR) by MCS. The effective dose was calculated to optimize the clinical dosage regimen. The results showed that AUC_inf, T_1/2Z, CL and V_C were (14.21±5.69) μg·h·mL^-1, (1.85±1.20) h, (803.11±297.78) mL·(kg·h)^-1, and (403.63±93.74) mL·kg^-1, respectively, after intravenous administration of 10 mg·kg^-1 BW. After oral administration of 10 and 20 mg·kg^-1 BW, the C_max were (1.70±0.27) μg·mL^-1 and (3.36±0.98) μg·mL^-1, the T_max were (1.30±0.48) h and (1.50±0.53) h, the AUC_inf were (5.01±0.80) μg·h·mL^-1 and (12.38±3.21) μg·h·mL^-1, T_1/2Z were (2.25±1.03) h and (2.31±1.00) h, and oral bioavailability were 33.84% and 43.08%, respectively. The TAR that bacteriostatic, bactericidal, and eradication of Pasteurella multocida under ECOFF (2 μg·mL^-1) by the low and high doses (10 and 20 mg·kg^-1 BW) of thiamphenicol powder were 26.96% and 86.03%, 10.77% and 58.89%, 9.40% and 49.62%, respectively, all of which were less than 90%. The 24 h dosage for bacteriostatic, bactericidal, and eradication was calculated as 43.1, 66.4 and 78.1 mg·kg^-1 BW, respectively. These results indicate that the current dosage regimen cannot realize the bacteria cure of chicken Pasteurella multocida infection and that at least 45 mg kg^-1 BW is necessary for effectiveness.

The objective of this study was to observe the growth-promoting effect of Macleaya cordata extract (MCE) on grass carp (Ctenopharyngodon idellus) and to characterize the pharmacokinetic properties and muscle residues of its main active components, sanguinarine (SAN) and chelerythrine (CHE). Four hundred and fifty grass carp weighing 10.5 g were randomly divided into 5 groups and fed with diets containing 0, 30, 60 and 120 mg·kg^-1 MCE Pulvis (MCEP) and betaine hydrochloride respectively for 60 days. A total of 120 grass carp weighing 250 g were randomly divided into 5 groups. MCE was administered intravenously (0.001 2 mg·kg^-1, 0.012 mg·kg^-1, 0.024 mg·kg^-1) or gavage (0.06 mg·kg^-1, 0.6 mg·kg^-1). The concentrations of SAN and CHE in blood were determined by liquid chromatography-tandem quadrupole mass spectrometry (LC-QQQ-MS). Another 150 grass carp of 50 g were fed with MCEP (60 mg·kg^-1 feed) for 60 days. SAN and CHE contents in skinned muscle of grass carp were determined by LC-QQQ-MS. The results showed that MCE could significantly improve growth performance and condition factor of grass carp (PP < 0.05); After oral administration of 0.6 mg·kg^-1 MCE, the main pharmacokinetic (PK) parameters of MCE, SAN and CHE administered orally at 0.6 mg·kg^-1 were C_max=19.157±1.924 and 6.388±1.356 μg·L^-1, AUC_(0-t)=3.317±0.274 and 0.651±0.114 (μg·L^-1)·h, T_1/2=9.065±2.286 h (CHE had no valid data), respectively. 5 min after intravenous injection of 0.0245 mg·kg^-1 MCE, AUC_(0-t) of SAN and CHE were 37.132±4.124 and 0.614±0.039 (μg·L^-1) ·h, AUC_(0-∞) were 60.583±7.512 and 0.750±0.055 (μg·L^-1)·h, respectively; In the residue assay, SAN and CHE in muscle decreased below the limit of quantification on day 5 after withdrawal. The results suggested that 60 mg·kg^-1 MCEP could significantly improve the growth performance of grass carp. SAN and CHE in plasma showed PK characteristics of fast absorption, wide distribution and rapid elimination. However, at high doses, the two active substances exhibit significant nonlinear PK profiles; SAN and CHE in muscle were almost completely eliminated after 5 days withdrawal of MCE. This study is of great significance in the rational use of MCE, its development and related risk assessment.

In this study, PLGA was used to encapsulate Salvia miltiorrhiza polysaccharide and Mn²⁺ with potent immune stimulation effect and good biosafety, and the immune enhancement effect of the system as an inactivated PCV2 adjuvant was evaluated. Firstly, we prepared a PLGA nano-adjuvant delivery system (SM-PLGA) co-loaded with Salvia miltiorrhiza polysaccharide and Mn²⁺ by double emulsion solvent evaporation method. The SM-PLGA was mixed with PCV2 antigen, and 100 μL was injected subcutaneously respectively into the left and right thighs of mice for the first immunization. At the same time, PCV2 group, Alhydrogel (Algel)-PCV2 group and the Control group were established, and on the 14th day after the first immunization, mice were immunized twice. Then, the activation of DCs in popliteal lymph nodes and inguinal lymph nodes were evaluated by flow cytometry on the 5th day after the first immunization. The serum of mice was collected on the 21st, 28th, 35th and 42nd day after the first immunization, and the PCV2 specific antibodies IgG, IgG1 and IgG2a were dynamically monitored to evaluate the enhancement effect of the adjuvant on PCV2 specific humoral immune response. The spleen lymphocytes of mice were collected on the 21st and 28th day after the first immunization, and the activation of CD4⁺T cells, CD8⁺T cells, CTL and memory T cells were measured, and the IFN-β, IFN-γ and IL-6 in the supernatant of the cells on the 28th day were measured. Finally, the lymph nodes of mice were collected on the 35th day after the first immunization to determine the activation of germinal center B cells. Through the results of the above three periods, the enhancement effect of SM-PLGA on cellular immune response was evaluated. SM-PLGA could significantly promote the activation of lymph node DCs on the 5th day after the first immunization, and continuously stimulate the secretion of PCV2-specific antibody IgG and its subtypes on the 21st to 42nd day after the first immunization. SM-PLGA could significantly promote the spleen CD4⁺T cells, CD8⁺T cells and CTL response on the 21st day after the first immunization, and still had a strong stimulating effect on memory T cells and Germinal center B cells on the 28th and 35th day after the first immunization. At the same time, it significantly promoted the secretion of related cytokines, IFN-β, IFN-γ and IL-6. The results showed that SM-PLGA, as an adjuvant for inactivating PCV2, could induce a potent Th1/Th2 immune response and provide a reference for the prevention of PCV2.

This study aimed to investigate the effects and feasibility of curcumin (CUR)-loaded exosomes derived from canine adipose mesenchymal stem cells (cADMSC-EXO) on skin wound healing. Mice and dogs were randomly divided into four groups: control group (CON), exosome treatment group (EXO), curcumin treatment group (CUR), and curcumin-loaded exosome group (EXO-CUR). For the wound model, a full-thickness skin wound with a diameter of 1 cm was created on the back of each mouse, and a 1.5 cm full-thickness wound on the back of each dog. Subcutaneous injections were administered on days 1, 3, 5, 7, and 9 for both species. The results showed that curcumin-loaded cADMSC-EXO significantly accelerated wound healing in both mouse and canine skin injury models, promoting the structural restoration of skin tissue. EXO-CUR enhanced wound repair by upregulating the expression of wound healing-related genes (VEGFA, FGF2) and the anti-inflammatory factor IL-10, while downregulating scar-related genes (SOX9, TGF-β1, Twist1) and upregulating TGF-β3, thereby reducing scar formation. Additionally, in mouse serum, levels of wound healing factors (VEGF, FGF2) increased, oxidative stress-related factor ROS decreased, and GSH levels rose. Furthermore, inflammatory factors (IL-1β, TNF-α) were reduced. These results indicate that cADMSC-EXO loaded with CUR can effectively promote the repair of skin damage, and is more effective than using CUR or EXO alone.

The aim of this study was to observe the isolation and culture of Leizhou goat umbilical cord mesenchymal stem cells (LZG-UCMSCs) and the effect on the treatment of drug-induced liver injury (DILI) in mice. Umbilical cord mesenchymal stem cells were isolated and cultured, growth curve, cell cloning, RT-PCR, immunofluorescence and induction experiments were performed from nine-year-old Leizhou goat placenta. 36 ICR mice were randomly divided into 3 groups: blank control group, model injury group and stem cell treatment group, with 12 mice in each group. The rats in the model group and the treatment group were given gavage at a dose of 15 mg·kg^-1 for 4 weeks. Aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were measured. The results showed that the cell morphology of the isolated and cultured LZG-UCMSCs was normal, with the characteristics of UCMSCs. Compared with the control group, the activities of ALT, AST and ALP in the injured group were significantly increased (P < 0.05). Compared with injury group, ALT, AST and ALP in treatment group were significantly decreased (P < 0.01). The results suggest that normal UCMSCs can be isolated from the placenta of Lezhou goat, and LZG-UCMSCs has a certain therapeutic effect on DILI in mice, thus providing reference value for further treatment of homologous goat DILI by LZG-UCMSCs.

Periodontitis refers to a series of inflammatory lesions caused by dental plaque that damage the periodontal tissue and its supporting structures. It is a common chronic, non-communicable disease in feline. At present, the research on cat periodontitis in China is relatively insufficient, and there is a lack of scientific prevention and control methods. In this study, samples from different areas of the oral cavity of healthy cats and cats with periodontitis were collected, and microbial species identification and antimicrobial susceptibility tests were carried out to provide medication recommendations for clinical treatment.The bacteriostatic effect of commonly used antibacterial agents after surgical cleaning was evaluated in order to provide a theoretical basis for the treatment of periodontitis in cats and home oral care. The results showed that, in all cats tested, Subgingival microbial species abundance is higher than supragingival ones. The abundance of oral microbial species in cats with periodontitis is higher than that in healthy cats. Porphyromonas and Treponema are higher in subgingival than supragingival. As potential pathogenic microorganisms, it is speculated that they may be the key pathogenic factors of periodontitis. Results showed that the oral microbiota of cats with periodontitis was more sensitive to Enrofloxacin and less sensitive to Metronidazole. In three oral care products with the antimicrobial peptides, the chlorhexidine gluconate and the silver ion as the main components respectively, the chlorhexidine gluconate and the silver ion have better bacteriostatic effect. But the chlorhexidine gluconate tastes bitter and has poor palatability for cats.It is recommended to be used as an oral antiseptic in surgery. In summary, Porphyromonas and Treponema may be the main pathogens of feline periodontitis. Enrofloxacin can be used as an empirical adjunctive therapy for feline periodontitis. It is recommended to use the Chlorhexidine gluconate in ultrasonic scaling, and to use the Silver ions after surgery.

In order to understand the epidemiological characteristics and antibiotic resistance of Pasteurella multocida (Pm) from pigs in China, isolation and culture of bacteria recovered from diseased and dead porcine organs from Heilongjaing, Liaoning, Jilin, Inner Mongolia, Shaanxi, Ningxia and Henan provinces were carried out. The bacteria were identified by 16S rRNA sequencing and kmt gene, and typed using capsular typing, lipopolysaccharide genotype typing, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). The sensitivity of Pm to 8 antibiotics was analyzed by the broth microdilution method. The whole genome sequencing of the bacteria was performed using Illumina PE 150, and the antibiotic resistance genes were analyzed using the ResFinder database. Finally, the virulence of the isolates was determined through the pathogenicity experiment in mice. The results showed that the isolates formed smooth, moist colonies with a slightly convex and surface on blood agar plates, Gram staining revealed that it was red, coccus or short rod-shaped bacteria. A total of 34 isolates of Pm were obtained, including 19 isolates of capsule serotype A (55.88%), 14 isolates of capsule serotype D (41.18%), and 1 isolate of capsule serotype F. There were 8 isolates of LPS genotype L3 and 26 isolates of LPS genotype L6. MLST analysis identified 8 MLST types, with ST11 being the predominant genotype, accounting for 35.29%. Pm can be divided into 21 PFGE profiles, with obvious diversity among isolates. The antibiotic resistance results showed that the resistance rates of the 34 isolates of Pm to polymyxin B, tetracycline, florfenicol, chloramphenicol, ceftiofur, ciprofloxacin, and kanamycin were 38.23%, 35.29%, 23.53%, 14.71%, 11.76%, 8.82%, and 2.94%, respectively, and none was resistant to gentamicin. The antibiotic resistance genes detection showed that 18 isolates of Pm carried 9 types of antibiotic resistance genes, namely tet(B), tet(C), tet(L), floR, aadA14, sul2, aph(6)-Id, aph(3″)-Ib, and aph(3′)-Ia. The capsule serotype A isolates of Pm were more virulent than capsule serotype D isolates. The experimental group of mice exhibited an 100% mortality rate following intraperitoneal injection of the PmA1 strain at a concentration of 31.5 CFU·mL^-1.In conclusion, it was shown that the prevalent serotypes of the 34 porcine-origin Pm isolates were capsule serotype A and capsule serotype D, and the MLST type was ST11. The virulence of Pm capsular serotype A isolates was higher than that of capsular serotype D isolates. Moreover, PFGE revealed that there is diversity among the isolates. The study provided a theoretical basis for the development of vaccines and prevention strategies against Pm infections.

The aim of this study was to develop a rapid, accurate and easy-to-use colloidal gold assay for Senecavirus A (SVA) antibody diagnosis for Senecavirus infection. The recombinant protein of SVA VP2 was obtained by prokaryotic expression and purification, and the VP2 protein polyclonal antibody was prepared. The VP2 protein was coupled with colloidal gold to form a gold labeled antigen. Subsequently, VP2 protein and VP2 polyclonal antibody were coated on nitrocellulosic membrane (NC membrane) as test line (T-line) and control line (C-line), respectively. Optimizing the reaction system to prepare test strips. The results showed that the prepared test strips had no cross reactivity and good specificity when detecting foot-and-mouth disease virus (FMDV) serotypes O and A (FMDV-O, FMDV-A), porcine reproductive and respiratory syndrome virus (PRRSV), classical swine fever virus (CSFV), pseudorabies virus (PRV), African swine fever virus (ASFV) positive serum and healthy pig (SPF) serum; The sensitivity of SVA positive serum was 1 ∶64. The kappa value of the strip and virus neutralization test (VNT) was 0.88 in 150 swine clinical samples, indicating that the two methods were highly consistent. In summary, an SVA antibody test strip was successfully developed by this study, which can be operated in 10 to 15 minutes, and has the advantages of being rapid, accurate and simple, providing an effective tool for clinical qualitative detection and on-site diagnosis of Senecavirus disease.

The aim of this essay was to establish a specific and sensitive novel detection method for porcine rotavirus A (PoRVA) using droplet digital PCR (ddPCR). This study designed specific primers and probes for PoRVA based on the conserved sequences of the VP6 gene from GenBank, and successfully constructed a ddPCR detection method for PoRVA by optimizing the reaction conditions and determined the specificity, sensitivity, repeatability, and made some clinical sample testing. The optimization of the reaction conditions showed that the optimal concentrations of upstream and downstream primers and the corresponding probe were 600 nmol·L^-1and 300 nmol·L^-1, respectively, with the highest copy number of virus-positive droplets and the best effect at an annealing temperature of 56 ℃ The specificity results show that the self-established detection method can only detect PoRVA, while the nucleic acid detection results for seven control viruses such as porcine deltacorona virus and porcine epidemic diarrhea virus are all negative. Sensitivity results showed that the detection limit of this method was 3.97 copies·μL^-1, which is 1 000 times and 10 times higher than that of conventional PCR (3 970 copies·μL^-1) and quantitative fluorescent PCR (39.7 copies·μL^-1), respectively. Repeatability results showed that the intra- and inter-group coefficients of variation were less than 10%. Testing of 142 clinical samples showed that the positive detection rate by ddPCR was higher than that of qPCR and PCR. The results indicate that the novel ddPCR detection method for PoRV established in this study has strong specificity, high sensitivity, and good repeatability. It is suitable for early infection diagnosis and epidemiological investigation of PoRV, and can provide a reliable means for continuous monitoring of porcine rotavirus epidemics in the future.

The aim of this study was to investigate the pathogen of piglet diarrhea and its genetic evolutionary characteristics as well as pathogenicity on a pig farm in Gansu Province, with a view to providing some references for the prevention and control of epidemics in this pig farm. In this study, the small intestine tissues of diseased pigs collected from the pig farm were processed, and then the common diarrhea pathogens of pigs were detected. Vero E6 cells were used to isolate the virus from the diseased materials with positive pathogen detection, and the identification, purification, genetic evolution analysis and piglet pathogenicity evaluation test of the isolated strains were carried out. The results showed that the samples collected by RT-PCR were positive for porcine epidemic diarrhea virus (PEDV). CPE observed that the cell contour disappeared, a large number of cells fell off, formed plaque, and the cells were drawn into a net. IFA observed specific green fluorescence in cells. Western blot showed the target band at 57 ku. The typical structural characteristics of the coronavirus were observed under the transmission electron microscope. The titer of purified virus was 10^6.0 TCID₅₀·mL^-1. Phylogenetic analysis showed that the isolate was closely related to SXSL and HK2021, and had a certain evolutionary distance from the traditional PEDV strain CV777. The experimental animals had severe diarrhea. Piglets were thin, emaciated, and had growth retardation. Anatomy showed that the small intestine wall became thinner, the small intestine was full, and the mesentery was congested. Pathological tissue sections showed that intestinal villi were shortened, broken and exfoliated, with scattered bleeding points and lymphocyte proliferation and necrosis. Immunohistochemical results showed that there were obvious positive signals in all segments of the small intestine, and the positive signal of PEDV in the ileum was the strongest. Genetic evolution analysis showed that the PEDV isolate belonged to the GⅡa type, and it was named LZ202401 strain. Pathogenicity analysis showed that it was a variant virulent strain, which was the main pathogen of diarrhea in piglets on the pig farm. This study provides a theoretical basis for further exploring the molecular characteristics and genetic evolution characteristics of PEDV, and provides a reference for the prevention and control of PEDV.

This study aimed to analyze the genetic variation and pathogenic characteristics of feline calicivirus (FCV) and successfully isolated and identified five prevalent FCV strains. A total of 127 clinical samples were tested, yielding 31 nucleic acid-positive samples (positivity rate: 24.4%). Five viral strains were isolated via cell culture. Results were as follows: Among them, four strains (e.g., HN78) were classified as FCV genotype Ⅰ, and one strain (HN77) as genotype Ⅱ. Electron microscopy revealed typical spherical, non-enveloped viral particles, and VP1 gene sequencing indicated 75.4%-75.65% homology among the strains. Animal challenge experiments confirmed that both genotype Ⅰ (HN78) and genotype Ⅱ (HN77) induced typical clinical symptoms, though pathogenic features differed between genotypes. This study provides the first systematic comparison of the biological characteristics of FCV genotypes Ⅰ and Ⅱ in China, offering critical viral strain resources and a theoretical foundation for vaccine development and clinical prevention strategies.

Coccidiosis disrupts the intestinal immune homeostasis of the host, serving as a major predisposing factor for Clostridium perfringens (CP)-mediated necrotic enteritis (NE). Among seven chicken Eimeria spp., Eimeria maxima (EM) is the most effective at inducing NE. Accordingly, the objective of this study is to establish a stable and reliable experimental model of NE by evaluating the impact of varying EM challenge doses. A total of 200 14-day-old broilers were divided into 10 groups: the control group, CP challenge group, EM infection groups (with varying infection doses), and EM/CP co-infection groups (with varying infection doses). At 14 days of age, different doses of EM sporulated oocysts were inoculated. 4 days post EM infection, CP isolates were inoculated for the challenge infection. The trial was terminated on Day 20, and all the chickens were sacrificed. The body weights (before the challenge and on Day 20) and the survival rate were recorded, and the lesions of the small intestines were scored. The results showed that with the increase of EM infection dose, the weight gain was gradually reduced in the single EM infection groups, whereas this trend was not observed in the EM/CP co-infection groups. The relative weight gain of the EM/CP1 group was significantly higher than those of the other EM/CP co-infection groups. However, no significant changes were observed across the EM/CP2, EM/CP3, and EM/CP4 groups. The lesion scores in the challenged groups showed a trend similar to the relative weight gains. The intestinal lesions in the EM/CP1 group were less severe than those in the other EM/CP co-infection groups, and there was no significant difference in gut lesions among the EM/CP2, EM/CP3, and EM/CP4 groups. In the EM/CP co-infection groups, the survival rate of the EM/CP2 group was 85%, while the survival rates of the EM/CP3 and EM/CP4 groups were lower, at 80% and 70%, respectively. Based on the comprehensive evaluation of the relative weight gains, intestinal lesions, and mortality, the EM/CP2 group dosage (1×10⁴ oocysts/bird + 1×10⁹ CFUs/bird) was determined to be the optimal infection dose for inducing an experimental model of NE. Consequently, this model provides a valuable research tool for the investigation of NE pathogenesis and the development of vaccines/drugs against NE.