The emergence of New Delhi metallo-beta-lactamase (NDM)-producing Escherichia coli (E. coli) in the food production chain poses a serious public health threat. This study aimed to investigate the prevalence and molecular characteristics of blaNDM-carrying E. coli along the chicken production chain (farms, slaughterhouses, and supermarkets) in Jiangsu Province, China. Between 2023 and 2025, 408 samples were collected, recovering 39 blaNDM-positive E. coli isolates (9.56%). Isolation rates were 10.4% (26/250) in farms, 10.1% (11/108) in slaughterhouses, and 4.0% (2/50) in supermarkets. Whole-genome sequencing (WGS) identified blaNDM-5 as the dominant variant, alongside the first detection of blaNDM-13 in local farm environments. All isolates exhibited high-level resistance to meropenem (MIC: 16-128 mu g/mL) and universal resistance (100%) to ampicillin, cefoxitin, ceftiofur, and sulfisoxazole. Notably, 41.03% and 7.69% of strains co-harbored the polymyxin resistance gene mcr-1.1 and the tigecycline resistance gene tet(X4), respectively. Isolates carried an average of 19.5 antimicrobial resistance genes, with IncFIB (AP001918) (82.05%) identified as the dominant plasmid replicon. Multilocus sequence typing (MLST) revealed 18 distinct sequence types (STs), with ST156 and ST155 being the most prevalent. Phylogenetic analysis confirmed slaughterhouses as critical hubs for cross-contamination, evidenced by shared STs (ST1158, ST155, ST162) and minimal SNP differences (1-11) between environment and carcass isolates. Furthermore, the detection of clinically relevant ST10 and ST69 clones in supermarket retail chicken meat underscores a direct foodborne transmission risk to humans. These findings highlight the poultry supply chain as a significant reservoir of multidrug-resistant blaNDM-positive E. coli. Accordingly, we recommend enhanced biosecurity protocols and stricter restrictions and controls on antimicrobial use in broiler farms.

Campylobacter is a major bacterial cause of gastroenteritis worldwide, and poultry meat is widely recognized as a principal reservoir for human Campylobacter infection. This study characterized the antimicrobial susceptibility profiles, genomic diversity, key antimicrobial-resistance determinants, and virulence genes of Campylobacter isolates collected from chicken farms and fresh retail poultry meat in ten regions of Jiangsu Province, China. The biofilm- forming capacity of selected strains was also evaluated. MLST identified CC-574 and CC-828 as the predominant clonal complexes of Campylobacter jejuni and Campylobacter coli, respectively. The isolates exhibited a broad range of sequence types (STs), including 21 previously documented STs in C. jejuni and 16 in C. coli, as well as six novel STs from C. jejuni and three novel STs from C. coli. Phylogenetic analysis revealed extensive genetic diversity among the Campylobacter isolates. Overall, 46.6 % of isolates were classified as MDR. The MDR proportion was significantly higher in C. coli (75.4 %) than in C. jejuni (17.5 %), and C. coli exhibited broader resistance across the ten antibiotics assessed. Among the detected resistance genes, the resistance-enhancing variant RE-CmeABC, which was primarily harbored by C. jejuni, had the highest prevalence (32.8 %), followed by tet(O) (31.3 %), the aminoglycoside resistance gene cluster aadEsat4-aphA-3 (21.9 %), and erm(B) (9.4 %). Virulence-gene profiling of the 128 Campylobacter isolates identified 10 virulence genes across five functional categories: adhesinon, invasion, immune modulation, motility, and toxin production. The wlaN gene, which is associated with Guillain-Barré syndrome, was detected in 7 (5.5 %) C. jejuni isolates. Among the 38 Campylobacter strains tested for biofilm formation, six C. coli isolates exhibited pronounce biofilm-forming capacity. These findings indicate that Campylobacter isolates from chicken farms and retail poultry meat pose potential public health risks, underscoring the need for targeted Campylobacter control strategies and providing a useful reference for future surveillance pograms.

Mitochondria are crucial carriers of maternal effects, and their function is closely related to energy metabolism and disease occurrence. Previous studies have shown that chickens with different mitochondrial haplogroups exhibit differences in production performance, but the underlying mechanism remains unclear. This study investigates the differences in mitochondrial structure and function-related indices between the A and E mitochondrial haplogroups (referred to as A-group and E-group) in recessive white-feathered chickens. It was achieved using in vivo fasting/refeeding models and an in vitro model of treating hepatocytes with nutritional factors (glucose and fatty acids). In vivo study indicated that compared to A-group chicken hepatocytes, E-group hepatocytes had shorter perimeters of mitochondria and shorter lengths of mitochondria associated with the endoplasmic reticulum membrane during refeeding (p < 0.05); mitochondria were more abundant (p = 0.05) but displayed compromised structural integrity during fasting; mitochondrial swelling was more severe during both refeeding and fasting (p < 0.01, p < 0.05); the protein level of mitofusin 2 (MFN2) was lower during fasting (p < 0.05); and there were more vacuoles and lipid accumulation in liver sections during refeeding (p < 0.05). In cultured hepatocytes, compared to A-group cells, E-group cells had higher reactive oxygen species (ROS) level after oleic acid treatments (p < 0.001); the protein level of microtubule-associated protein 1A/1B-light chain 3 beta (LC3) was lower after glucose treatment (p < 0.01), and the protein levels of MFN2 and LC3 were lower after oleic acid treatment (p < 0.01, p < 0.05). These findings suggest that mitochondrial haplogroups are associated with mitochondrial structure and function, oxidative stress, autophagy, and lipid metabolism of chicken hepatocytes in response to energy stimulation. The findings may explain how mitochondrial haplogroups affect chicken production performance.

The widespread use of enrofloxacin (ENR) in poultry farming raises public-health concerns due to residue persistence, particularly in indigenous chickens where standard withdrawal times (WTs) may be inadequate. This study characterized depletion kinetics of ENR and its metabolite ciprofloxacin (CIP) across five commercially relevant breeds in China. We developed and validated a sensitive LC-MS/MS method for simultaneous quantification of ENR and CIP in four edible tissues. After oral administration at 10 mg/kg body weight (bw) once daily for 5 days, tissues from AA broilers, WOD168, Jinling Partridge, Xueshan, and Jinling black-bone chickens were sampled at six time points through day 14. Results showed pronounced breed-dependent differences in elimination. White-feathered lines (AA and WOD168) cleared residues rapidly, with concentrations at or below maximum residue limits (MRLs) within 3 days. In contrast, yellow-feathered breeds showed markedly prolonged persistence, especially in skin with fat. Jinling black-bone chickens exhibited the most extreme retention, with residues detectable in all tissues at day 14 and skin with fat reaching 898.96 μg/kg, a value nearly nine-fold the MRL. WTs were estimated with WT 1.4 using the EMA 95/95 approach under Chinese MRLs, with residues expressed as ENR plus CIP. Overall WTs were 2.30 to 2.64 days for white-feathered lines and 8.16 to 39.74 days for yellow-feathered breeds, with skin with fat consistently the limiting tissue. These findings provide a scientific basis for breed-specific withdrawal guidance and identify skin with fat as a critical monitoring target to ensure poultry food safety.

This study aimed to evaluate the maternal genetic diversity and mitochondrial population structure of once endangered indigenous chicken breeds in China under current conservation conditions. The genetic characteristics of six endangered indigenous chicken breeds, namely the Bian chicken, Jinyang Silky chicken, Pudong chicken, Xiaoshan chicken, Zhongshan Shalan chicken, and Pengxian Yellow chicken, were analyzed based on mitochondrial DNA (mtDNA) D-loop region sequences. Blood samples were collected from the wing vein. The D-loop region was amplified by PCR, and genetic characteristics were analyzed using bioinformatics approaches. A total of 368 individuals were amplified and sequenced, yielding complete D-loop sequences of 1231 and 1232 bp. Sequence alignment identified 42 polymorphic sites, with a hypervariable region primarily located between 167 and 446 bp. The overall haplotype diversity, nucleotide diversity, and the average number of nucleotide differences were 0.876 ± 0.010, 0.00603 ± 0.00012, and 7.426, respectively, with significant inter-breed variation. Haplotype analysis identified 32 haplotypes belonging to haplogroups A, B, C, E, F, and G. The proportion of breed-specific and shared haplotypes varied among breeds, and several high-frequency haplotypes were widely distributed across populations. Analysis of molecular variance (AMOVA) indicated that the majority of genetic variation occurred within breeds (83.41%), whereas among-breed variation accounted for 16.59% (Fst = 0.166), suggesting moderate population differentiation. The median-joining haplotype network exhibited a radial pattern centered on several core haplotypes, with no evidence of breed-specific clustering of maternal lineages. Neutrality tests (Tajima’s D and Fu’s Fs) yielded non-significant results, consistent with neutral evolution. However, mismatch distribution analyses suggested possible population expansion in the Zhongshan Shalan chicken and Pengxian Yellow chicken. In summary, the six endangered indigenous chicken breeds retain a moderate level of maternal genetic diversity under current conservation conditions. However, differences among breeds were observed in the maintenance of genetic diversity and population structure.

Flavor-related compounds and nutritional components of chicken meat vary among different breeds, but comprehensive comparisons of these characteristics between commercial and indigenous chickens remain insufficiently characterized. In this study, three chicken breeds (Arbor Acres, Chengkou, and Langshan) were slaughtered at their respective market ages, and the volatile flavor compounds, amino acids, fatty acids, and lipidomic profiles of thigh muscle were analyzed to investigate breed-associated differences in flavor-related and nutritional characteristics. Langshan chickens exhibited the highest total volatile compound content and also had the highest total amino acid levels, with significantly higher contents of umami and sweet amino acids. In addition, both indigenous breeds showed higher levels of arachidonic acid (C20:4n6) than Arbor Acres broilers, while Chengkou chickens had the highest content of docosahexaenoic acid (DHA, C22:6n3). Lipidomic analysis identified 787 lipids, with glycerophospholipids and sphingolipids as the predominant classes. Differential lipid analysis revealed that Langshan chickens had 38 upregulated lipids compared with Arbor Acres chickens, while Chengkou chickens exhibited 258 differential lipids relative to Arbor Acres chickens. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that these differential lipids were mainly associated with glycerolipid, sphingolipid, and glycerophospholipid metabolism. Correlation analysis further revealed significant associations between specific lipids and flavor-related compounds, amino acids, and fatty acids, suggesting their potential roles in breed-associated differences. Overall, this study demonstrates that indigenous chicken breeds possess distinct flavor-related and nutritional profiles compared with commercial Arbor Acres broilers and provides valuable insights into breed-associated differences in chicken meat characteristics.

Carbapenem-resistant bacteria, in particular NDM-producing Enterobacteriaceae, have become a great threat to the global public. The blaNDM-13 is a novel blaNDM variant with increasing dydrolytic activity against cefotaxime. This study aimed to investigate the molecular characteristics of blaNDM-13-positive E. coli in a chicken farm located in Jiangsu Province of China. Six blaNDM-13-positive E. coli strains were isolated from 83 samples, including cloacal samples (n = 4), cages (n = 1), and water dispensers (n = 1). Antimicrobial susceptibility testing showed that these isolates exhibited pan-resistance to β-lactams (meropenem MIC≥32 μg/mL), colistin, and six other antibiotic classes, retaining susceptibility only to tigecycline. Illumina sequencing showed that isolates harbored multiple resistance genes, with fosA3, aph(3′)-IIa, oqxA, oqxB, and aph(6)-Id being present in all strains. Notably, blaCTX-M-65 (extended-spectrum β-lactamase), mcr-1.1 (colistin resistance), and qacE (disinfectant genes) were detected in 50 %, 66.67 %, and 66.67 % of blaNDM-13-positive E. coli strains, respectively. MLST classified the isolates into ST155 (n = 3), ST93 (n = 2), and ST1158 (n = 1), with blaNDM-13-positive ST155 E. coli isolates found to be horizontal transmission between chicken and environmental surface samples. Three representative isolates were subjected to Nanopore long-read sequencing; the blaNDM-13 was located on the IncFII plasmid, which showed high homology with clinical (pB5-1) and poultry-derived plasmids (YZLc23-1-NDM-13-96k), harboring conserved resistance gene clusters (IS91-blaNDM-13-bleMBL-IS50R-aph(3′)-IIa-IS26-IS6-fosA3), and confirmed horizontal transfer via conjugation. The conjugants were stably inherited after 15 days of passage and exhibited no significant differences in growth rates when compared to E. coli J53. This study identifies blaNDM-13-carrying multidrug-resistant E. coli clones in poultry production systems, transmitted via poultry-environment interactions and plasmid-mediated gene transfer. Farm-level surveillance targeting high-risk transmission routes is essential to control antimicrobial resistance and protect poultry health.

Polystyrene nanoplastics (NPs) threaten agricultural ecosystems and the food chain; however, their hepatotoxicity in chickens, a key poultry species, remains unclear. This study investigated the effects of chronic NP exposure on hepatic metabolism to evaluate food safety risks in poultry products. Chickens were orally exposed to 100 nm polystyrene NPs via feed for 120 days. Histopathological evaluation, serum biochemical analysis revealed hepatotoxicity in NP-exposed poultry, characterized by histopathological liver injury, elevated lipid droplet accumulation, significantly increased alanine aminotransferase (ALT) activity, and elevated triglyceride (TG) levels (p < 0.05). Untargeted LC-MS/MS Metabolomics profiling identified 193 differentially abundant metabolites—predominantly organic acids and lipids—with L-leucine and NADH emerging as pivotal metabolic hubs. A KEGG pathway analysis demonstrated significant enrichment in purine metabolism and oxidative phosphorylation, while a gene set enrichment analysis (GSEA) confirmed the suppression of ABC transporters. Notably, the key biomarkers 9-cis-retinal and phenylalanyl phenylalanine were significantly altered, reflecting metabolic disturbances linked to NPs exposure. Overall, this study characterized exposure-associated metabolic signatures and established NP-induced hepatic injury phenotypes in poultry production systems.

As mitochondria play an important role in nutritional/energy metabolism, nutritional disturbances may affect animal growth, development and performance through modulating mitochondrial structure and function. This study aimed to elucidate the effects of nutritional disturbances on mitochondrial structure and function, oxidative stress, and fat deposition in the hepatocytes of chickens with A or E mitochondrial haplogroups (referred to as A-group and E-group). For in vivo experiments, white-feathered broiler chickens were fasted for 12 h or refed for 2 h after 10 h fasting. For in vitro experiments, chicken embryonic primary hepatocytes were treated with 50 mmol/L glucose or 0.25 mmol/L oleic acid. Data indicated that compared to fasted chickens, fat content (p < 0.01), the number of aggregated ribosomes (p < 0.05), and mitochondrial membrane potential (p < 0.05) were increased in the refed chickens of both haplogroups. However, the number of mitochondria was reduced (p < 0.01) and ROS level was increased (p < 0.05) in the refed E-group chickens, and the protein levels of MFN2 and SOD2 were reduced (p < 0.05) in the refed A-group chickens. Moreover, compared to the control cells, triglyceride content was increased in the cells of both haplogroups (p < 0.01), ROS level was reduced in the E-group cells (p < 0.01), and mitochondrial membrane potential was reduced (p < 0.05) and CYTB protein content was increased (p < 0.05) in the A-group cells after treatment with oleic acid. In addition, mitochondrial membrane potential was increased in the A-group cells after treatment with glucose (p < 0.01). These results indicate that nutritional disturbances affected fat deposition, mitochondrial membrane potential, the number of aggregated ribosomes, and ROS level in chicken liver cells. Moreover, ROS level, mitochondrial number, mitochondrial membrane potential, and the abundance of certain mitochondrial proteins were different between the A- and E-groups or between glucose and oleic acid treatments. These findings provide references for improving animal physiological functions and production performance by adjusting nutritional levels.

NPs have become a concerning global environmental problem. Dietary exposure to NPs can cause microbial dysbiosis. However, the risks of NPs to animals, particularly poultry species such as chickens, remain poorly understood. In this study, chickens were continuously exposed to 100 nm NPs via dietary inclusion from 18 weeks of age for 120 days to evaluate the effects of NPs on intestinal health. We found that NPs accumulated in chicken intestinal tissues, leading to adverse alterations in the intestinal mucosal structure, such as villus atrophy and goblet cell depletion, and significantly altering intestinal length. The 16S rRNA sequencing revealed significant gut microbiota dysbiosis, characterized by a loss of diversity and shifts in key bacterial groups. Functional predictions of the microbiota revealed impairments in metabolic pathways, especially carbohydrate and amino acid metabolism. Furthermore, network analysis showed that microbial interactions were disrupted and key functional hubs were lost. Most importantly, NPs exposure led to a significant decline in egg quality parameters, including eggshell thickness and strength, yolk color, weight, shape index, and Haugh units. Correlation analyses connected specific taxa, such as Methanobrevibacter, Rikenellaceae_RC9_gut_group, and Prevotellaceae_UCG-001, to intestinal damage and declines in egg quality. These findings provide a scientific basis for assessing the health risks of NPs in animals and offer insights into the development of gut health interventions.

Due to the lack of pronounced sexually dimorphic traits in many poultry species, or the presence of such traits only in adulthood, visual sexing becomes a challenging task, which can result in considerable difficulties in breeding and conservation management. This study performed laboratory sex identification analysis of eleven poultry species based on the sexing gene Spindlin (SPIN). Genomic DNA was extracted from blood or feather samples, encompassing both males and females. PCR was performed using primers SPIN319F and SPIN472R, which flanked intron 2 of SPIN. The outcomes were visualized using agarose gel electrophoresis and capillary electrophoresis plots. The length polymorphism between SPIN-W and SPIN-Z homologous genes allows for clear sex discrimination in chicken, Japanese quail, pheasant, turkey, guinea fowl, chukar partridge, mallard duck, Muscovy duck, mule duck, swan goose, and rock pigeon. The result demonstrated that SPIN was relatively conserved within the same species. We found strong support for the monophyletic grouping of all W sequences from three avian orders in one clade and of all Z sequences in the other. The research indicates that the SPIN marker is effective for genetic sex identification in the poultry species tested in this study.

The experiment aimed to investigate the effects of combined use of mannan oligosaccharides and Lactobacillus salivarius on the growth performance, immune organ development, intestinal morphology, and serum biochemical indicators of yellow-feathered broilers. A total of 360 one-day-old healthy yellow-feathered broiler chicks with uniform body weight were randomly divided into four groups, with three replicates per group and 30 chickens per replicate. The control group (CON group) was fed a basal diet, the mannan oligosaccharide group (MOS group) was supplemented with 0.3% mannan oligosaccharides, the Lactobacillus salivarius group (SAL group) was supplemented with 0.8% Lactobacillus salivarius, and the combined group (MOS + SAL group) was supplemented with 0.3% mannan oligosaccharides and 0.8% Lactobacillus salivarius. The experimental period lasted for 63 days.The results showed that compared with the CON group, the average daily gain and average daily feed intake of the SAL group and MOS+SAL group were significantly increased from 43 to 63 days (P<0.05). On the 63rd day, the body weight was significantly increased (P<0.05). The spleen index and bursa of Fabricius index in the MOS group and MOS+SAL group were significantly increased (P<0.05). The villus height of the duodenum in the SAL group and MOS + SAL group was significantly increased (P<0.05), and the villus height to crypt depth ratio in the MOS+SAL group was significantly increased (P<0.05). The ileal villus height in the MOS group and MOS + SAL group was significantly increased (P<0.05). Compared with the CON group, the concentrations of serum total protein and albumin in the SAL group and MOS+SAL group were significantly increased (P<0.05), and the activity of alkaline phosphatase was extremely increased (P<0.01). The study indicates that feeding of Lactobacillus salivarius and mannan oligosaccharides to yellow-feathered broilers is beneficial for improving growth performance, promoting healthy development of the intestine, and enhancing the development level of spleen and bursa of fabricius, with the combined feeding effect being better than separate feeding.

MHC in chicken demonstrates a great range of variations. This study was conducted to investigate the major histocompatibility complex-B (MHC-B) variability in three representative broiler breeds with large breeding populations in China namely Arbor Acres (AA), 817 broilers (817), and Jinling Partridge (JL). The three Chinese broilers were analyzed with a subset of 89 SNPs in the MHC-B SNP panel. The genotypes of these SNPs were obtained using multiplex PCR targeted amplicon sequencing. The haplotypes were analyzed through a combination of manual and computational haplotype reconstruction methods using PHASE program. The phylogenetic tree was constructed based on haplotypes using MrBayes program. A total of 67 haplotypes were identified within three broilers populations, among which three haplotypes from the AA and 817 populations shared the standard MHC-B SNP (BSNP) haplotype. No matching haplotypes were detected in the JL population. Phylogenetic analysis based on these SNPs did not reveal clearly defined population clusters. This study reveals a high level of genetic diversity within the MHC-B region, highlighting the importance of this functionally significant genomic region in the three broilers. However, the observed genetic patterns indicate a complex relatedness structure among the three populations. These findings indicate the need for further investigation to better understand the evolutionary dynamics and functional implications of MHC-B variation.

Campylobacter is a major cause of bacterial foodborne diarrhea worldwide. Consumption of raw or undercooked chicken meat contaminated with Campylobacter is the most common causative agent of human infections. Given the high prevalence of contamination in poultry meat and the recent rise of multi -drug -resistant (MDR) Campylobacter strains, an effective intervention method of reducing bird colonization is needed. In this study, the Campylobacter-specific lytic phage CP6 was isolated from chicken feces. Phage CP6 exhibited a broad host range against different MDR Campylobacter isolates (97.4% of strains were infected). Some biological characteristics were observed, such as a good pH (3-9) stability and moderate temperature tolerance (<50 degree celsius). The com plete genome sequence revealed a linear double -stranded DNA (178,350 bp, group II Campylobacter phage) with 27.51% GC content, including 209 predicted open reading frames, among which only 54 were annotated with known functions. Phylogenetic analysis of the phage major capsid protein demonstrated that phage CP6 was closely related to Campylobacter phage CPt10, CP21, CP20, IBB35, and CP220. CP6 phage exerted good antimicrobial effects on MDR Campylobacter in vitro culture and reduced CFUs of the host cells by up to 1 -log compared with the control in artificially contaminated chicken breast meat. Our findings suggested the potential of CP6 phage as a promising antimicrobial agent for combating MDR Campylobacter in food processing.

1. Male and female Chukar partridges are difficult to differentiate based on their morphology or by the Chromobox-Helicase-DNA binding (CHD) during early growth.2. The current study developed a novel, simple, low-cost and rapid sexing protocol for Chukar partridges based on the newly defined sexing gene ubiquitin-associated protein 2 (UBAP2).3. The length of polymorphism between UBAP2-W and UBAP2-Z homologous genes allows for easy sex discrimination in this species. Molecular sexing analysis was based on the simultaneous amplification of both genes, resulting in two distinct amplicons (947 bp and 535 bp) in heterogametic females and only a single band (535 bp) in homogametic males, which is easy to detect with agarose gel electrophoresis.4. This technique is simple and convenient for genetic sex determination in Chukar partridges.

The prevalence of antimicrobial resistance originating from animals presents a significant threat to the treatment of animal disease, public health, and food safety. Researchers have focused on antibiotic resistance in Escherichia coli (E. coli), yet there are few reports on the resistance change during the feeding cycle. The purpose of this study was to investigate the prevalence and antibiotic resistance changes of E. coli in animal, environmental, and human samples during the broiler feeding cycle. Epidemiological surveys were performed in a farm with feeding AA broilers in Yangzhou, Jiangsu Province, China. Results showed that during a 42-days feeding cycle, 128 E. coli isolates were obtained from the cloaca of white-feathered broilers (n = 140), with an isolation rate of 91.4%, 27 E. coli isolates were obtained from Feed (n = 70) and 35 E. coli isolates were obtained from cage swabs (n = 70). A workers’ hands swabs sample isolation rate of 68.6% (24/35) was observed. Antibiotic susceptibility testing revealed that out of 214 E. coli isolates, varying degrees of resistance were observed against 14 antibiotics. Most strains were resistant to ampicillin, cephalothiophene, ciprofloxacin, tetracycline, sulfamisoxazole, sulfamethoxazole and florfenicol, with a resistance rate exceeding 80%. The resistant strains demonstrated relatively stable patterns in their resistance to various antibiotics. Of the six antibiotic resistance genes tested, the floR gene showed the highest detection rate (72.4%), followed by qnrS (43.0%), mcr-1 (35.0%), aadE-Sat4-aphA-3 (28.0%), blaNDM (8.4%), aac(6′)-lb (3.7%), and cfr (0). The highest detection rate for virulence genes was yijp. In summary, the isolation rate of E. coli and antibiotic resistance profile in broiler chickens remained stable throughout their feeding cycle. These findings can serve as a reference for the rational use of antibiotics in clinical settings, they can guide the use of veterinary drugs in poultry breeding.

This study discussed the haplotype characteristics of mitochondrial control region (D-loop region) of broiler breeds with different growth rates as well as the relationships between different haplotypes and growth performance. The D-loop region's sequence size of the 974 individuals from 20 broiler breeds ranged from 1,231 to 1,232bp, as a C base deletion at 859 bp. A total of 52 mutation sites and 72 haplotypes were detected, which were divided into four haplogroups, A, B, C and E. Of these, haplogroup E was the dominant haplogroup among 817 broilers and all medium/fast-growing broiler breeds. While its proportion was not exceed 40.00% among others types breeds. Correlation analysis showed that there was a significant negative correlation between birth weight and haplogroup A and a significant positive correlation between birth weight and haplogroup E. Age in days and feed conversion ratios were positively correlated with haplogroup B but negatively correlated with haplogroup E when the average body weight was approximately 1.8 kg. The cluster analysis showed that haplogroups A and B with Gallus gallus spadiceus and E with Gallus gallus murgha, respectively clustered into one branch. This study provided a theoretical basis for broiler breeding and genetic resource protection, development and utilization.

乌骨鸡(Gallusgallusdon2esticus)是我国优良的鸡遗传资源,通常被认为具有一定药用价值.为研究我国乌骨鸡品种的遗传多样性,对丝羽乌骨鸡、东乡绿壳蛋鸡、金湖乌凤鸡、余干乌骨鸡和竹丝鸡等5个乌骨鸡品种的197个个体线粒体DNA的Cytb基因全序列进行检测.结果表明:5个乌骨鸡品种的Cytb基因序列全长为1 143 bp,共检测到15个核苷酸多态位点,界定出9个单倍型.总体单倍型多样性、核苷酸多样性和平均核苷酸差异分别为0.715±0.018、0.001 23±0.000 54和1.404.中介网络图分析显示,5个乌骨鸡品种单倍型呈星状发散分布,不同群体包含的单倍型存在一定的差异,形态学和地理分布不明显.遗传距离分析表明,竹丝鸡和丝羽乌骨鸡遗传距离较远,母系可能来自其他品种.这一研究为我国乌骨鸡遗传资源的保护、选育和鉴定提供了遗传背景信息.

为了探索亲鸽哺育乳鸽期间使用地美硝唑后亲鸽和乳鸽体内地美硝唑(DMZ)残留分布及代谢规律,制定适合肉鸽生产的休药期规范.本试验于亲鸽开始哺乳第1天以拌料和灌胃2种方式投喂DMZ,停药后不同时间采集亲鸽、乳鸽组织和鸽乳,采用液相色谱串联质谱法测定DMZ及其代谢物残留量.结果显示,亲鸽采用饲喂和灌胃2种方式投喂DMZ后第1天亲鸽肌肉、肝脏、肾脏和皮脂中DMZ及其代谢物残留量均达到峰值,灌胃方式给药后第1天皮脂中DMZ及其代谢物含量高达6 591.7 μg/kg,随后各组织残留量逐渐下降;饲喂方式给药后亲鸽肌肉、肝脏、肾脏和皮脂中药物消除时间分别为16 d、19 d、19 d和19 d,灌胃方式下分别为22 d、22 d、19 d和19 d;乳鸽各组织中药物残留代谢规律与亲鸽基本类似,最高残留量是灌胃后乳鸽皮脂组织,为500.7 μg/kg;饲喂方式给药后乳鸽肌肉、肝脏、肾脏和皮脂中药物消除时间分别为16 d、16 d、16 d和13 d,灌胃方式下分别为13 d、19 d、16 d和13 d;2种给药方式下第10天鸽乳中均无药物检出.结果表明,亲鸽使用DMZ,饲喂方式给药建议亲鸽休药时间为19 d,乳鸽为16 d;灌胃方式给药建议亲鸽休药时间为22 d,乳鸽为19 d.

Genomic selection（GS） is a popular molecular breeding method in the field of livestock and poultry breeding. It has been applied in practical breeding and made great progress. Genomic selection uses mathematical model to calculate the effect value of high-density markers across the whole genome to obtain the individual Genomic estimated breeding value（GEBV）,then carry out the efficient selection and matching of seed. This method can improve the accuracy of traditional breeding value estimation, achieve the early selection of livestock and poultry breeding, shorten generation interval, and accelerate genomic progress. At the same time, with the continuous maturity of the second-generation sequencing platform and gene chip technology, single nucleotide polymorphism（SNP） markers have become a common and important means of animal and plant research, and the cost of SNP chip detection is no longer high. This paper reviewed the common genome selection models and their applications in poultry breeding, discussed the existing challenges, and put forward to its application prospect, in order to provide reference for the protection, evaluation and utilization of local poultry in China.