Monitoring and identification of spoilage-related microorganisms in braised chicken with modified atmosphere packaging during refrigerated storage

This study mainly monitored the dominant bacterial populations and identified the spoilage-related microorganisms of braised chicken meat stored under different CO_(2)-modified atmosphere packaging(MAP)during refrigerated storage using a culture-dependent method and 16S rDNA identification.The quality changes and shelf life of the meat were also measured.The growth rate of total viable count(TVC)in braised chicken was slower with an increase of CO_(2) content in MAP,which also occurred in the remaining bacterial species monitored(lactic acid bacteria,Pseudomonas spp.,Brochothrix thermosphacta).The MAP exerted beneficial effects on the quality of braised chicken,as demonstrated by retarding the production of total volatile basic nitrogen(TVB-N)and delaying lipid oxidation(TBARS test).A total of 14 isolates were identified from braised chickens with different packaging at the end of storage,these included P.fragi(6 isolates),P.psychrophila(2 isolates),Enterococcus faecalis(3 isolates),B.thermosphacta(2 isolates),Staphylococcus equorum(1 isolate).

Are the two polymorphic sites of anti-Marek’s disease in White Leghorn chickens also suitable for Partridge Shank chickens?

Background:The selection of Marek’s disease(MD)-resistant breeds in Partridge Shank chicken,a popular local chicken breed in Henan Province of China,has practical value.We hypothesized that the two polymorphic sites(rs14527240 located in SMOC1 and GGaluGA156129 located in PTPN3)related to MD resistance in White Leghorn chickens are also applicable to Partridge Shank chickens.Methods:In this experiment,we screened 10 live hens and 2 live roosters with the double GG genotype by genotyping the two sites from 6500 Partridge Shank chickens.Nineteen one-day-old chicks with the double GG genotype were obtained by artificial insemination.Seventy-two one-day-old chickens(19 from the population expansion test and 53 randomly selected from chicken farms)were injected with 2000 plaque-forming units of the Md5 virus strain.After 100 days of infection,all chickens were examined by pathological anatomical examination,histological sectioning,genotyping,and a quantitative polymerase chain reaction of SMOC1 and PTPN3.Results:There was only one site(rs14527240 located in SMOC1)associated with MD in Partridge Shank chickens(p<0.05),but the GG genotype of SMOC1 in Partridge Shank chickens indicated susceptibility to MD.SMOC1 expression in MD-susceptible chickens was also significantly higher than that in MDresistant chickens(p<0.05).Conclusion:Therefore,the MD resistance sites selected from White Leghorn chickens were not completely suitable for Partridge Shank chickens,but they can be used as a reference.This study indicated that SMOC1 plays an important role in screening for MD resistance in poultry.

Encapsulated peracetic acid as a valid broad‑spectrum antimicrobial alternative,leading to beneficial microbiota compositional changes and enhanced performance in broiler chickens

Background Antimicrobial alternatives are urgently needed,including for poultry production systems.In this study,we tested the potential broad-range antimicrobial alternative peracetic acid,delivered in feed via the hydrolysis of encapsulated precursors through a 28-day study using 375 Ross 308 broiler chickens.We tested two peracetic acid concentrations,30 and 80 mg/kg on birds housed on re-used litter,and we evaluated the impact of both levels on gut microbial communities,bacterial concentration,antimicrobial resistance genes relative abundance and growth performance when compared to control birds housed on either clean or re-used litter.Results Body weight gain and feed conversion ratio improved in peracetic acid fed birds.At d 28,birds given 30 mg/kg of peracetic acid had a decreased Firmicutes and an increased Proteobacteria abundance in the jejunum,accompanied by an increase in Bacillus,Flavonifractor and Rombustia in the caeca,and a decreased abundance of tetracycline resistance genes.Chicken given 80 mg/kg of peracetic acid had greater caecal abundance of macrolides lincosamides and streptogramins resistance genes.Growth performance on clean litter was reduced compared to reused litter,which concurred with increased caecal abundance of Blautia,decreased caecal abundance of Escherichia/Shigella,Anaerostipes and Jeotgalicoccus,and greater gene abundance of vancomycin,tetracycline,and macrolides resistance genes.Conclusions Peracetic acid could be used as a safe broad-spectrum antimicrobial alternative in broilers.Encapsulated precursors were able to reduce the bacterial concentration in the jejunum whilst promoting the proliferation of probiotic genera in the caeca,especially at the low peracetic acid concentrations tested,and improve growth performance.Moreover,our findings offer further insights on potential benefits of rearing birds on re-used litter,suggesting that the latter could be associated with better performance and reduced antimicrobial resistance risk compared to clean litter rearing.

Intestinal toxicity of deoxynivalenol is limited by supplementation with Lactobacillus plantarum JM113 and consequentially altered gut microbiota in broiler chickens

Background: Limited research has focused on the effect of Lactobacillus on the intestinal toxicity of deoxynivalenol(DON).The present study was conducted to investigate the role of Lactobacillus plantarum(L.plantarum) JM113 in protecting against the intestinal toxicity caused by DON.Methods: A total of 144 one-day-old healthy Arbor Acres broilers were randomly distributed into 3 treatments,including the CON(basal diet),the DON(extra 10 mg/kg deoxynivalenol),and the DL(extra 1 × 109 CFU/kg L.plantarum JM113 based on DON group) treatments.The growth performance,organ indexes,intestinal morphology,pancreatic digestive enzymes,intestinal secreted immunoglobulin A(sIgA),jejunal transcriptome,and intestinal microbiota were evaluated.Results: Compared with the CON and DL groups,the DON supplementation altered intestinal morphology,especially in duodenum and jejunum,where villi were shorter and crypts were deeper(P < 0.05).Meanwhile,the significantly decreased mRNA expression of jejunal claudin-1 and occludin(P < 0.05),ileal rBAT and jejunal GLUT1 of 21-day-old broilers(P < 0.05),as well as duodenal PepT1 and ileal rBAT of 42-day-old broilers were identified in the DON group.Moreover,supplementation with L.plantarum JM113 could increase duodenal expression of IL-10 and IL-12 of 21-dayold broilers,ileal s IgA of 42-day-old broilers,and the bursa of Fabricius index of 21-day-old broilers.Further jejunal transcriptome proved that the genes related to the intestinal absorption and metabolism were significantly reduced in the DON group but a significant increase when supplemented with extra L.plantarum JM113.Furthermore,the bacteria related to nutrient utilization,including the Proteobacteria,Escherichia,Cc-115(P < 0.05),Lactobacillus and Prevotella(P < 0.1) were all decreased in the DON group.By contrast,supplementation with L.plantarum JM113 increased the relative abundance of beneficial bacterium,including the Bacteroidetes,Roseburia,Anaerofustis,Anaerostipe,and Ruminococcus bromi(P < 0.05).Specifically,the increased abundance of bacteria in the DL group could be proved by the significantly increased caecal content of propionic acid,n-Butyric acid,and total short-chain fatty acid.Conclusions: L.plantarum JM113 enhanced the digestion,absorption,and metabolic functions of the gut when challenged with DON by reducing the injury to intestinal barriers and by increasing the abundance of beneficial bacterium.

Effects of Bacillus subtilis CSL2 on the composition and functional diversity of the faecal microbiota of broiler chickens challenged with Salmonella Gallinarum

Background： The chicken gastrointestinal tract contains a diverse microbiota whose composition and structure play important roles in gut functionality. In this study, microbial shifts resulting from feed supplementation with Bacillus subtilis CSL2 were evaluated in broilers challenged and unchallenged with Salmonella Gallinarum. To analyse bacterial community composition and functionality, 454 GS-FLX pyrosequencing of 16 S r RNA gene amplicons was performed.Results： The Quantitative Insights into Microbial Ecology（QIIME） pipeline was used to analyse changes in the faecal microbiota over a 24-h period. A total of 718,204 sequences from broiler chickens were recorded and analysed. At the phylum level, Firmicutes, Bacteroidetes, and Proteobacteria were the predominant bacterial taxa. In Salmonellainfected chickens（SC）, Bacteroidetes were more highly abundant compared to control（NC） and Bacillus-treated（BT）chickens. At the genus level, in the NC and BT groups, Lactobacil us was present at high abundance, and the abundance of Turicibacter, unclassified Enterobacteriaceae, and Bacteroides increased in SC broilers. Furthermore, taxon-independent analysis showed that the SC and BT groups were compositional y distinct at the end of the 24-h period. Further analysis of functional properties showed that B. subtilis CSL2 administration increased gut-associated energy supply mechanisms（i.e. carbohydrate transport and metabolism） to maintain a stable microbiota and protect gut integrity.Conclusions： This study demonstrated that S. Gallinarum infection and B. subtilis CSL2 supplementation in the diet of broiler chickens influenced the diversity, composition, and functional diversity of the faecal microbiota. Moreover, the findings offer significant insights to understand potential mechanisms of Salmonel a infection and the mode of action of probiotics in broiler chickens.

Analysis of DNA methylation of CD79B in MDV-infected chicken spleen

Marek’s disease(MD),an immunosuppressive disease induced by Marek’s disease virus(MDV),provides an ideal model for studying diseases caused by a carcinogenic virus.CD79 B is a B-cell antigen receptor complex-associated protein β-chain precursor which is involved in the activation,proliferation,differentiation of B-cell and the transmission of downstream signals.This study analyzed CD79 B gene mRNA expression and methylation by two schemes#20(5′flanking to intron 1)and#27(intron 2 to intron 3),between MDV-infected tumorous spleens(TS)and non-infected spleens(NS).Results showed that average methylation levels of CpGs in #20 and #27 were higher in TS than in NS(P<0.05),while,CD79 B mRNA expression was lower in TS than in NS(P<0.01).Six of 40 CpG sites showed significantly(P<0.05)different methylation levels between TS and NS.Correlation analysis showed that the average methylation level rather than a single site methylation level in #20 affected(P<0.05)mRNA expression.Collectively,it was found that the change of CD79 B gene expression after MDV infection might be partly explained by modification of DNA methylation.

Vaccine by Chicken Line Interaction Alters the Protective Efficacy against Challenge with a Very Virulent plus Strain of Marek’s Disease Virus in White Leghorn Chickens

Marek’s disease (MD) is a lymphoproliferative disease of domestic chickens caused by Marek’s disease virus (MDV), an oncogenic and highly contagious α-herpesvirus. MD has been controlled by vaccination but sporadic outbreaks of MD still occur in some parts of the world. Efforts to improve vaccine efficacy have continued in both research communities and vaccine industries. We reported the host genetic variation affecting Marek’s disease vaccine-induced immunity in chickens earlier. In this study, we evaluated chicken lines, vaccines, and line by vaccine interaction on the protective efficacy of vaccination against MD. Specific pathogen free chickens from the relatively resistant line 63 and the highly susceptible line 72 were primarily used to evaluate the protection by three kinds of vaccines (rMd5ΔMeq, CVI988/Rispens, and HVT) upon challenge with a very virulent plus strain of MDV, vv+648A. Our data confirmed that both the chicken line and the vaccine significantly affected the protective efficacy of vaccination and showed that a chicken line by vaccine interaction, in most of the trials, also altered vaccine protective efficacy. More interestingly, although the protective index of all vaccine strains was higher in resistant than in susceptible line of chickens, the difference for HVT protection was striking and warrants further study. The findings may have important implications for vaccine development as well as for selective use of particular vaccines in specific lines of chickens to achieve maximum protection at minimized costs.

Molecular Characteristics of S1 Gene of Infectious Bronchitis Virus Isolated from Chicken Proventriculus

Infectious bronchitis virus was isolated from swollen proventriculi of clinically ill chicken. The suspected virus samples (2/97, 3/97, 1/98) were adapted in SPF chicken embryos for virus isolation and identification. All the virus isolates were able to agglutinate chicken erythrocytes after treatment with trypsin, and interfer with the reproduction of Newcastle disease virus in chicken embryos, and have low antigenic relat-edness values with reference positive IBV. The isolates 2/97, 3/97, 1/98 RNAs extracted from the allantoic fluid of inoculated embryonated eggs were converted to cDNA by reverse transcription with 3'-primer of S1 gene of (IBV). Polymerase chain reaction (PCR) was performed with two primers which span the S1 gene. Amplified product of 1. 93 kb was subjected to EcoR I and BamH I digestion and the fragments obtained were the same as expected size. The PCR product was ligated to pBlueScript-SK ( + ) vector, and its nucleotide sequence was determined by the dideoxy-mediated chain termination method. Nucleotide sequence analysis showed 73. 6 - 99. 7% homology between the isolated IBV and the IBV strains in GenBank. The homology of amino acid was 71. 4 - 99.4%.

Marek’s disease virus challenge induced immune-related gene expression and chicken repeat 1 (CR1) methylation alterations in chickens

Marek’s disease virus (MDV) challenge induces lymphoma in susceptible chickens. Host genes, especially immune related genes, are activated by the virus. DNA methylation is an epigenetic mechanism that governs gene transcription. In the present study, we found that expression of signal transducer and activator of transcription 1 (STAT1) was upregulated at 10 days post infection (dpi) in MD susceptible chickens, whereas interleukin 12A (IL12A) was elevated in both resistant and susceptible chickens. However, we did not observe MDV-induced DNA methylation variations at the promoter CpG islands (CGIs) in STAT1 and IL12A. Interestingly, the methylation levels at Chicken Repeat 1 (CR1), the transposable elements (TEs) located upstream of two genes, were different between resistant and susceptible chickens. Furthermore, a mutation was identified in the CR1 element near IL12A. The impact of the point mutation in transcriptional factor binding is to be examined in the near future.

Sequence and phylogenetic analysis of chicken reoviruses in China

supported by the China Animal Disease Prevention and Control Center;the China Agriculture Research System Poultry-Related Science and Technology Innovation Team of Peking, China （CARS-PSTP）

Comparison of Immune Effect of Four Commercial Marek's Disease Vaccines in Wenchang Chicken

Marek＇s disease（MD） is a lymphoproliferative disease of domestic chickens caused by a highly infectious,oncogenic alpha-herpesvirus known as Marek＇s disease virus（MDV）.The aim of this study was to compare the efficacy of four commercial MDV vaccines in Wenchang chicken.The 1-day old Wenchang chickens tested were injected with one of four different vaccines or not unvaccinated as control;five days later,they were then challenged by virulent MDV strain MD5.The results showed that,in comparison with HVT vaccines,the CVI988 vaccine gave the immunized chickens more potent immunities against challenges of MDV strain MD5.

酒糟蛋白替代豆粕对九斤黄鸡生长性能、血清生化和免疫指标的影响

[目的]研究不同比例的湿磨预处理去壳酱香型酒糟蛋白(wet milling pretreated and dehulled-moutai distiller's grains, WDMDG)替代豆粕对九斤黄鸡生长性能、血清生化和免疫指标的影响,为WDMDG替代豆粕提供科学依据。[方法]选取1日龄健康九斤黄公雏450只,随机分为3组,每组设3个重复,每个重复50只鸡,对照组饲喂基础日粮,试验Ⅰ和试验Ⅱ组分别在基础日粮中添加5%、8%WDMDG等营养替代豆粕,试验为期26 d,分别测定九斤黄鸡平均日增质量、平均日采食量、料重比和死淘率,并对九斤黄鸡血清中总蛋白、白蛋白、尿素氮含量、谷丙转氨酶和谷草转氨酶活力和IgG、IgA、lgM水平进行测定。[结果]与对照组相比,试验Ⅰ和试验Ⅱ组九斤黄鸡的各项生产性能均没有显著差异,试验Ⅰ和试验Ⅱ组鸡血清中尿素氮含量分别提高了4.88%(P>0.05)和19.51%(P<0.05),各组鸡血清中总蛋白、白蛋白含量、谷草转氨酶和谷丙转氨酶活力及IgG、IgA和IgM水平差异均不显著。[结论]在九斤黄鸡日粮中采用5%WDMDG等营养替代基础日粮中部分豆粕,对其日增质量、料重比、死淘率、血清生化指标和免疫指标均无显著负面影响。

鸡源类人乙肝病毒与人乙肝病毒S基因序列分析

为揭示动物乙肝病毒与人乙肝病毒之间的相关性研究打下基础，以人乙肝病毒Ｓ基因两侧的保守区域作为模板，采用套式ＰＣＲ方法，成功地扩增出鸡源类人乙肝病毒部分基因（１．２ｋｂ）。序列分析结果表明，鸡源类人乙肝病毒与人乙肝病毒Ｓ基因似有一定的同源性，但在保守区域（Ｓ区）内存在较大的核苷酸序列差异。

基于18 S rRNA的鸡组织滴虫病PCR诊断方法的建立

河南某鸡场约4周龄鸡疑似发生鸡组织滴虫病。根据鸡组织滴虫18 S rRNA序列设计引物,提取肝脏、盲肠内容物寄生虫DNA,采用PCR方法检测。结果表明,PCR扩增到与预期大小一致的产物,经测序比对,证实为鸡组织滴虫感染。所建立的PCR方法具有灵敏、特异、快速等优点,不仅能用于鸡组织滴虫病临床诊断,还能用于开展流行病学研究。

藏鸡副鸡嗜血杆菌的分离及16S rDNA序列分析

四川省某藏鸡场藏鸡发生以鼻腔与窦发炎、颜面肿胀、流鼻涕和打喷嚏为主要特征的疾病,通过对送检病鸡病原的分离纯化、生化鉴定、16 S rDNA基因的克隆和序列分析诊断为副鸡嗜血杆菌感染,将该株副鸡嗜血杆菌的16 S rDNA序列与GenBank中15株巴氏杆菌科菌株进行同源性分析发现,与6株副鸡嗜血杆菌同源性较高,为94.2%～97.2%,与其它菌株16 S rDNA基因的同源性较低。另外,药敏试验表明,本菌株对菌必治、阿莫西林、庆大霉素、头孢氨噻肟和阿奇霉素等药物敏感。

基于RF-DS图谱信息融合的孵化早期鸡胚蛋性别无损检测

针对图像或光谱单一信息检测孵化早期胚蛋性别识别率不高的问题,该研究提出一种随机森林(Random Forest,RF)和证据理论(Dempster-Shafer,D-S)的图谱信息融合的无损检测方法。利用机器视觉和光谱仪分别采集孵化期第4天水平横放的胚蛋信息,在对胚蛋图像和光谱预处理的基础上,提取图像纹理特征和光谱特征,再分别以2类单特征的RF分类结果作为独立证据构造基本概率分配函数,运用D-S证据理论进行决策级融合,根据分类判决门限得出最终的识别结果。试验结果表明,图像和光谱单特征RF模型识别准确率最高分别达78.00%和82.67%,多特征决策融合识别法准确率达到88.00%,其中雌雄识别率分别达到90.00%和86.25%,单个鸡蛋的平均判别用时为2.843 s。结果表明,该光谱-图像信息融合方法可以提高孵化早期胚蛋雌雄识别准确率。

基于16S rRNA测序分析冰鲜鸡腐败过程中微生物变化

为分析冰鲜鸡腐败过程中微生物变化,筛选冰鲜鸡腐败相关菌群,研究利用16 S rRNA测序技术分析了保存1、3、5和7 d冰鲜鸡样本微生物组成和多样性,利用正交偏最小二乘法回归和逐步多元回归分析筛选与冰鲜鸡腐败相关的菌属。结果显示:冰鲜鸡腐败过程中微生物丰富度和均匀度均显著下降,保存5 d和7 d样本与保存1 d和3 d样本微生物组成存在显著差异,4 d可能为冰鲜鸡腐败变质的临界点;筛选到27个冰鲜鸡腐败相关的候选菌属,其中肉食杆菌属、沙雷氏菌属和发光杆菌属可能为引起冰鲜鸡腐败变质的优势菌属。研究结果有助于加深对冰鲜鸡腐败变质机理的理解。

A novel apidaecin Api-PR19 synergizes with the gut microbial community to maintain intestinal health and promote growth performance of broilers

Background: Antibiotic growth promoters(AGPs) have been used as growth promoters to maintain animal intestinal health and improve feed efficiency in broilers by inhibiting pathogen proliferation. In view of the growing emergence of antibiotic-resistant pathogen strains and drug residue issues, novel treatments are increasingly required. This study aimed to compare two antimicrobial approaches for managing pathogen infection and maintaining animal intestinal health in broilers by supplying Apidaecin Api-PR19 and AGPs over 42 d of a feeding trial.Results: Compared with the broilers that were only fed a corn-soybean basal diet(CON group), supplementation with Api-PR19 and AGP(respectively named the ABP and AGP groups) both increased the feed conversion efficiency. When compared with the AGP group, Api-PR19 supplementation could significantly increase the organ index of the bursa of fabricius and subtype H9 antibody level in broiler chickens. Moreover, when compared with the CON group, the intestinal villus height, intestinal nutrient transport, and intestinal s Ig A content were all increased in the Api-PR19 group, while AGP supplementation was harmful to the intestinal villus height and intestinal nutrient transport. By assessing the antibacterial effect of Api-PR19 and antibiotics in vitro and in vivo, we found that Api-PR19 and antibiotics both inhibited the growth of pathogens, including Escherichia coli and Campylobacter jejuni. Furthermore, by using 16 S r RNA gene sequencing, the beneficial bacteria and microbiota in broilers were not disturbed but improved by apidaecin Api-PR19, including the genera of Eubacterium and Christensenella and the species of uncultured_Eubacterium_sp, Clostridium_asparagiforme, and uncultured_Christensenella_sp, which were positively related to improved intestinal development, absorption, and immune function.Conclusion: Apidaecin Api-PR19 treatment could combat pathogen infection and had little negative impact on beneficial bacteria in the gut compared to antibiotic treatment, subsequently improving intestinal development,absorption, and immune function.

Salmonella Typhimurium infection disrupts but continuous feeding of Bacillus based probiotic restores gut microbiota in infected hens

Background:The gut microbiota plays an important role in the colonisation resistance and invasion of pathogens.Salmonella Typhimurium has the potential to establish a niche by displacing the microbiota in the chicken gut causing continuous faecal shedding that can result in contaminated eggs or egg products.In the current study,we investigated the dynamics of gut microbiota in laying chickens during Salmonella Typhimurium infection.The optimisation of the use of an infeed probiotic supplement for restoration of gut microbial balance and reduction of Salmonella Typhimurium load was also investigated.Results:Salmonella infection caused dysbiosis by decreasing(FDR<0.05)the abundance of microbial genera,such as Blautia,Enorma,Faecalibacterium,Shuttleworthia,Sellimonas,Intestinimonas and Subdoligranulum and increasing the abundance of genera such as Butyricicoccus,Erysipelatoclostridium,Oscillibacter and Flavonifractor.The higher Salmonella Typhimurium load resulted in lower(P<0.05)abundance of genera such as Lactobacillus,Alistipes,Bifidobacterium,Butyricimonas,Faecalibacterium and Romboutsia suggesting Salmonella driven gut microbiota dysbiosis.Higher Salmonella load led to increased abundance of genera such as Caproiciproducens,Acetanaerobacterium,Akkermansia,Erysipelatoclostridium,Eisenbergiella,EscherichiaShigella and Flavonifractor suggesting a positive interaction of these genera with Salmonella in the displaced gut microbiota.Probiotic supplementation improved the gut microbiota by balancing the abundance of most of the genera displaced by the Salmonella challenge with clearer effects observed with continuous supplementation of the probiotic.The levels of acetate and butyrate in the faeces were not affected(P>0.05)by Salmonella challenge and the butyrate level was increased by the continuous feeding of the probiotic.Probiotic supplementation in Salmonella challenged chickens resulted in higher level of propionate.Continuous probiotic supplementation decreased(P<0.05)the overall mean load of Salmonella in faeces and had a significant effect on Salmonella load reduction in internal organs.Conclusions:Salmonella challenge negatively impacts the diversity and abundance of many gut microbial genera involved in important functions such as organic acid and vitamin production.Strategic feeding of a Bacillus based probiotic helps in restoring many of the microbial genera displaced by Salmonella Typhimurium challenge.

LC-MS/MS测定鸡蛋、鸡肉和蛋糕中氟虫腈及代谢物残留量

建立液相色谱-串联质谱(liquid chromatography-tandem mass spectrometry,LC-MS/MS)法测定鸡蛋、鸡肉和蛋糕中氟虫腈及其代谢物残留量的方法。样品经酸性乙腈提取,经Cleanert PEP Plus(60 mg/3 m L)固相萃取柱净化,Agilent Eclipse plus C18色谱柱(2.1 mm×100 mm,1.8μm)分离,以0.1%甲酸乙腈溶液和0.1%甲酸水溶液(含10 mmol/L乙酸铵)为流动相进行梯度洗脱,电喷雾负离子模式电离,多反应监测模式检测,外标法定量。对鸡蛋、鸡肉和蛋糕3种基质效应进行了试验。结果表明1μg/kg～50μg/kg范围内线性关系良好,相关系数R2>0.99。方法的检出限为0.4μg/kg,定量限为1μg/kg。在鸡蛋、鸡肉和蛋糕中分别添加1、2、5μg/kg 3个水平进行加标回收试验,回收率为82.3%～112.5%,相对标准偏差为1.2%～4.5%。该方法具有较高的灵敏度和准确度,适用于鸡蛋、鸡肉和蛋糕中氟虫腈及残留物的测定。