The major expressed MHC class I and beta 2-microglobulin (β2m) genes were cloned from a silky chicken breed and Numida Meleagris breed (the MHC class I genes were designated BF2*SI and BF2*NM , respectively ). The allelic polymorphisms in the population of the two chicken breeds were investigated. The amino acids homologies among BF2*SI, BF2*NM alleles were 75.5%～93.9% and 81.1%～98.5%, respectively. Compared with human HLAA2, seven of key amino acids of the peptide binding sites were conserved in BF2*SI, but six in BF2*NM. Twenty-four high amino acids substitution sites (amino acids substitutions ratio≥4.0) were found in the peptide-binding domain (PBD) of BF2*SI , and two sites (position 69 and 9) displayed the amino acids substitutions ratio≥8.0. Unlike BF2*SI, only six high amino acids substitution sites were found in the PBD of BF2*NM. The numbers of high amino acids substitution sites in PBD of Leghorn chicken BF2 was lower than that of BF2*SI, but higher than that of BF2*NM. According to homology ratios, α1, α2, α3 of BF2*SI were classed into 4, 3 and 3 types, and α1, α2, α3 of BF2*NM were classed into 3, 3 and 1 types, respectively. Six BF2*SI genes were subdivided to 5 lineages (A, B, C, D and E), whereas five BF2*NM genes were subdivided to 3 lineages (A, B, C). Comparison the amino acids homology ratios of α1, α2 domains in BF2*SI, BF2*NM with that in BF2* 21 with resistance to MDV revealed that BF2*03SI, BF2*04SI, BF2*05NM were most similar to BF2* 21 in α1 domains (with homology ratios of 86.4%, 86.4%, 87.5%, respectively), and BF2*05SI, BF2*05NM were most similar to BF2* 21 in α2 domains (with homology ratios of both 93.4%). The β2m genes of silky chicken breed and Numida Meleagris breed could be classed into 2 types (type 1,type 2) based on the amino acids sequences of mature peptides. The type 1 was identical to the β 2m genes of Leghorn chicken(accession number M84767) , but type 2 only had the homology ratio of 87.5% with type 1. The results suggested that the BF2 and β2m genes of each chicken breed own its special molecular characters.

A DNA fragment encoding rabbit defensin NP2 was cloned based on the published amino acid sequence and the biased codon usage of Pichia Pastoris. The modified rabbit defensin NP2 DNA fragment was inserted into Pichia Pastoris expression vector pGAPZα. Then the plasmid pGAPZαA- NP2 was transferred to E. coli JM109 and used for Pichia pastoris transformation. The recombinant linearized with restriction enzyme BlnI was transformed into special strain Pichia pastoris SMD1168. The positive clones were selected with PCR, and the recombinant rabbit defensin NP2 was detected with SDS-PGAE, and quantified with Bradford and then used for biological activity assay. The results show that the modified rabbit defensin NP2 can express in the Pichia pastoris, with the well ability to inhibit the growth of E. coli 5α. These findings have provided valuable tools for further studies on the function and medicinal application of NP2.

We isolated and sequenced a 480 bp cDNA encoding mature bovine interleukin-18 (bIL-18) from alveolar macrophages and splenocytes activated with LPS by RT-PCR. The bIL-18 gene was cloned into pET32a (+) vectors and sequenced. Nucleotide sequence of bIL-18 shares high homology with cattle. Fusional expression with pET32a (+) of bIL-18 of about 38ku was obtained by SDS-PAGE analysis after induction by IPTG in the E.coli BL21 expression system. The recombinant protein can augment T cell proliferation ConA-stimulated and IFN-γ production by MDBK. The IL-18 mRNA was constitutively detected in bovine alveolar macrophages with or without LPS, While, enhanced expression was detected in splenocytes and liver cells if treated by LPS, and can be weakly detected in peripheral blood mononuclear cells (PBMCs) treated by activators. Significant deference of IL-18 mRNA level may reflect the capacity to produce mature IL-18 in such tissues.

VR1020 was first used as the eukaryotic expression plasmid to construct LH-β eukaryotic expression system. The recombinant plasmid was detected by the plasmid PCR and BamHⅠ，BglⅡ digestion to identify the correct insert orientation, the new plasmid was named VPLH-β. VPLH-β was transformed into E. coli DH5α competent cells. The ability of VPLH-β to express full-length porcine LH-β in vitro was confirmed by RT-PCR in Cos7 cells that were transiently transfected with VPLH-β in the entrapment of Lipofectamine. 48 BALB/c female mice at the age of 2 weeks were divided into 3 groups and were vaccinated intramuscularly in the left and right quardriceps respectively with 100μg VPLH-β, with 100μg VR1020; Saline solution was used as control treatment. The blood of mice were collected from tail vain on 7, 14, 21, 28 days after inoculation to determine the dynamic changes of the content of LH-β and FSH in the sera. The reproduction of mice was also detected. The experimental results indicated that the VPLH-β, we first recombined, could correctly express in vitro by using the Lipofectamine entrapment system. In the animal research, the amount of LH and FSH were significantly raised in the mice inoculated with VPLH-β plasmid, which was correlated with reproduction performance of the mice that produced more young mice than the control mice. These results indicate that the inoculation with VPLH-β could remarkably raise the content of LH and FSH in the sera of mice and promote the reproduction performance.

Two bovine genomic DNA pools were composed of 36 high-milk-yield Chinese Holstein cattles (milk yield in 305 days>8 500kg) and 32 low-milk yield Chinese Hostein cattles (milk yield<5 600kg). 24 high polymorphic RAPD primers selected from 320 arbitrary primers were used for analyzing genetic difference between two DNA pools. 5 specific fragments were obtained from DNAs of two groups cattles. 4 of them were sequenced and converted to SCAR markers. The results of statistic analysis showed that SCAR marker yield-S139 was highly associated with milk yield trait. By electronic cloning method the marker was extended from 921 bp to 2 141 bp. As a result, the fragment was a repeat element of LINE family in bovine genome by homologous analysis. So it was reasonably to assume that some QTLs or major genes associated with milk yield trait maybe lied in this LINE region.

This study sequenced partial sequences of mitochondrial DNA Cyt b gene (420 bp) of 42 individuals and D-loop region (910 bp) of 28 individuals in 5 cattle breeds from Sichuan Province. The results showed that there were 5 mutation sites among the partial Cyt b gene and 7 haplotypes, which was divided into two main types. There were 64 mutation sites and 28 haplotypes defined in Dloop region when the 22 published Chinese cattle D-loop sequences aligned together with the data in this study. Haplotype H1~H23 was belonging to Bos. Taurus type while Bos. Indicus type contained haplotypes from H24 to H28. 67.86% individuals were Bos. Taurus type and 32.14% were Bos. Indicus type in Sichuan cattle breeds. It suggested that the Sichuan cattle were mainly origined from Bos. Taurus type and Bos. Indicus type.

One growth trial was conducted to investigate the effect of epidermal growth factor (EGF), glutamine(Gln) and porcine growth release factor gene plasmid (pGRF gene plasmid) on the performance, immune function and the level of growth related hormone of early weaned piglets. In this experiment fortytwo piglets (Landrace×Large White×Taihu, initial weight^#4.51 kg),weaned at 28 days, were picked out from five litters and allotted randomly to seven equivalent groups according to a one factorial design. The EGF, Gln and pGRF gene plasmid were administrated to all piglets, injected or added to the diets directly, in EGF, Gln, pGRF gene plasmid, EGF＋Gln, EGF+pGRF gene plasmid and EGF+Gln+pGRF gene plasmid treatments respectively. Growth, food consumption, ileal apparent digestibility of protein, index of hair color, diarrhea and contents of immune globulin G (IgG) as well as the growth hormone and glucocorticoid were measured. The simultaneous administration of EGF, Gln and pGRF gene plasmid (EGF+Gln+pGRF gene plasmid) exerted much better effects than that of the separate use of any of them. This is also true for the combined administration (EGF＋Gln and EGF+pGRF gene plasmid). As for the EGF+Gln+pGRF gene plasmid group, the final weight, ADG, ileal apparent digestibility of protein and index of hair color were increased by 48.02% (P<0.01) and 1.68 times (P<0.01), 1.13 times (P<0.01) and 14.03% (P<0.05) respectively while the food consumption were decreased by 50.75% (P<0.01) compared with the control. In addition, there was no diarrhea occurred in this trial. As far as the immune function was concerned, the effects of EGF+pGRF gene plasmid and EGF+Gln+pGRF gene plasmid were much better than that of other treatments. As shown in this experiment, the levels of IgG in EGF+pGRF gene plasmid and EGF+Gln+pGRF gene plasmid groups were increased by 11.71% (P<0.05) and 11.24% (P<0.1) separately in the first week postweaned while were decreased by 9.53% (P<0.05) and 5.06% (P<0.1) individually. Moreover, the endocrine system was influenced by administration of EGF, Gln and pGRF gene plasmid to much degree. The effect of EGF+Gln+pGRF gene plasmid was better marked than that of pGRF gene plasmid and EGF+pGRF gene plasmid groups. The concentration of glucocorticoid was decrease by 40.40% in the first week and 88.57% in the second week respectively compared with the pGRF gene plasmid and EGF+pGRF gene plasmid treatments. In contrast with the change of level of glucocorticoid , the concentration of growth hormone was increased to some degree. However, the rule of this change is the same for GH and glucocorticoid.

Ninety six crossbred Duroc×(Landrace×Largewhite) weanling piglets weighing (5.27±0.49) kg were randomly allocated to 4 treatments , 4 replicates of 6 piglets each (half male, half female). Piglets per treatments were respectively fed one of the experimental diets supplemented with glutamine dipeptide at a level of 0%, 0.125%, 0.25% and 0.50% , to study effect of the different levels of glutamine dipeptide in diet on the growth performance, cell immunity and serum biochemical index of weanling piglets. The result indicated that the supplement of 0.125%~0.50% glutamine dipeptide in diets improved feed conversion rate, strengthened cell immunity, increased serum growth hormone concentration and decreased cortisol concentration. High supplemental level of glutamine dipeptide (0.50%) significantly increased serum SOD value. Optimum supplemental level of glutamine dipeptide in diet for weanling piglets were 0125% ~0.25%.

Ribosomal small-subunit RNA gene-sequence of eight Chinese Babesia stocks infective to cattle, including one Babesia bigemina isolate, one B. bovis isolate, three Babesia ovata isolates, one Babesia major isolates and two unnamed Babesia sp. isolates (Babesia U sp.), were cloned and analyzed. The target DNA segments were amplified by PCR and the products were ligated into the pGEMT Easy vector for sequencing. The length of the 18S rRNA gene of all Babesia species involved in this study varied between 1 653～1 699 bp. The phylogenetic trees were constructed based on 18S rRNA sequence of the Chinese isolates as well as other species of Babesia available in GenBank. The results showed that Chinese isolates of Babesia bovis and Babesia bigemina were in the same branch with corresponding foreign isolates respectively; B. ovata transmitted by Haemaphysalis longicornis were locateded in the same group with B. ovata Korea, and homology among them exceed 96.5%; B. major transmitted by H. punctata was situated in another branch, and the homology with other bovine Babesia species is less than 92.5%; Two isolates B. U sp. is dispensed on the same branch with B. caballi, and the homology with other bovine Babesia species is less than 91.8%. These results indicated that there are five Babesia pecies infective for cattle in China, including B. bovis, B. bigemina, B. major, B. ovata and Babesia U sp.

Immunity against chicken coccidiosis by in ovo vaccination of Eimeria necatrix in diffevent invasive stages was investigated. The fertile Lingnanhuang broiler eggs were injected through amniotic sac on day 15, 17 and 19 of incubation with oocysts, sporocysts or sporozoites of E.necatrix, respectively. Vaccination doses were in the range of 3×10³~1×10⁴ oocysts, 4×10³~4×10⁴ sporocysts, or 8×10³~8×10⁴ sporozoites per egg. Hatching rates were generally unaffected by vaccination. The hatched chicks were reared in wire-cages and shed oocysts during day 2~7 posthatch for chickens vaccinated with sporozoites and at 7 d posthatch for chicks injected using oocysts or sporocysts. At 17 d, the vaccinated chickens were challenged with 1.2×10⁵ sporolated oocysts of E.necatrix. The immunity against E.necatrix by in ovo vaccination were evaluated through relative weight gain(RWG), reduction of lesion score(RSL), and relative oocyst production(ROP). The chickens vaccinated in ovo with parasite stages had significantly reduced oocysts output(ROPs were in range of 28.1%~60.2%) and lesion score(ranged in 50%~74.9%), and with significant increase in RWG(reached to 73.2%~90.5%) compared to their nonimmunized counterparts. These results implies that vaccination in ovo of E.necatrix invasive stages could induce sufficient immunity against the homologous challenge.

Species-specific primers for Contracaecum rudolphii A, Contracaecum rudolphii B and Contracaecum septentrionale, namely HFA(F), HFA(R), HFB(F) and HFS(F), were designed based on sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2) of ribosomal DNA. Under optimal amplification conditions, specific rDNA fragments of 323bp, 321bp and 108bp in length were amplified by PCR for C. rudolphii A, C. rudolphii B and C.septentrionale, respectively, while no fragment was amplified from gDNAs from other parasites used as controls. The lowest DNA concentration that the assay could amplify was 1.6, 21.8 and 0.27 ng/μL for C. rudolphii A, C. rudolphii B and C.septentrionale, respectively. These assays could be used for the accurate and rapid identification of members of the C. rudolphii complex, and for the differentiation between C.septentrionale and the C. rudolphii complex. These methods could provide tools for the diagnosis and epidemiological survey of infections these anisakids caused.

The complete 18S rRNA gene of Babesia orientalis parasited in buffalo in China was obtain by PCR. It was sequenced and then blasted. The result indicated that the parasite belonged to the genus Babesia .The 1 700 bp complete gene sequence was compared with 15 other Babesia sp. availabled in GenBank. The data were analyzed and a phylogenetic tree was established. The result indicated that the parasite was close to Babesia sp. of South Africa and B.ovis, and the distant was far to B.bigemina and B.bovis. This result indicated that it was no doubtful that it was a new species. It proved that the Buffalo babiesiosis was not mixinfected by B.bigemina and B.bovis .

The clinical capacity of the nematode-trapping fungus——Arthrobotrys oligospora to kill parasitic nematodes of livestock was studied. The experiment indicated that the killing rate was 96.3% (sheep), 96.5% (cattle), 97.4% (horse) respectively after feeding the conidia to animals, which showed that the fungus could pass through the digestive canal of animals and have preserved its trapping capacity. The result established an important foundation for the clinical application of nematode-trapping fungi.

An investigation of classⅠintegron and its gene cassette epidemiology in 192 Escherichia coli strains isolated from a swine farm was carried out by the methods of PCR, sequence, and restriction enzyme analysis. The result showed that one-hundred and five strains (54.7%) of E. coli harbored six types of classⅠintegron in the form of eight combinations. All of E. coli strains from the pigs, the raisers, and the surroundings had similar prevalence of classⅠintegron, but the strains with the same resistant patterns did not always carry the same type of classⅠintegron. Each type of classⅠintegron integrated different kinds and numbers of gene cassette. Among all the detected classⅠintegrons, one-hundred percent carried aminoglycoside adenyltransferase (aadA), seventy-seven percent carried dihydrofolate reductase (dhfr), whereas only a small percentage carried one or two of the beta-lactamase (bla), streptothricin acetyl-transferase (sat), and erythromycin esterase (ereA) genes. All E. coli strains carried classⅠintegrons were multi-resistant, especially resistant to compound sulfamethoxazole (100%), streptomycin (90%), and spectinomycin (75%). High prevalence of classⅠintegrons carrying dhfr and aadA genes had occurred in E. coli strains because sulfonamides and aminoglycosides were used extensively, especially used as antibacterial growth promoter in this swine farm.

240 Avian-2000 commercial broilers were allocated equally into a normal temperature control group (NT), a low temperature group (LT) and a low temperature with supplemental L-arginine group (LA) at day 14 of age. Starting on day 14, birds in groups LA and LT were subjected to the same low temperature by lowing 1~2 °C per day from 28 °C (d 14) down to 12~14 °C (d 21), and remained constant until day 49. Starting on day 14, an additional 100 mg/kg L-arginine was added to the basal diets of group LA. Incidence of pulmonary hypertension syndrome (PHS) was recorded. Right/total ventricle ratio (RV/TV), plasma nitric oxide (NO), vessel wall area to vessel total area ratio (WA/TA), and mean media thickness of pulmonary arterioles (mMTPA) were measured at days 24, 32, 39 and 45 of age. Apoptosis of smooth muscle cells in pulmonary arterioles were detected using TdT-mediated dUTP-biotin nick end labeling (TUNEL) kit. It was found that birds in the group LT had increased PHS incidence, RV/TV, WA/TA and mMTPA compared with those in the group NT. Birds in the group LA tended to have lower WA/TA and mMTPA than those in the group LT, and this tendency was pronounced on day 32. Plasma NO concentration was increased in the group LA compared to that in the groups NT and LT from days 32 to 45, but there were no differences between the groups LT and NT despite an exception on day 39. Birds in the group LA had increased apoptotic to total smooth muscle cells ratio than those in the groups NT and LT; however, there were no differences between the groups LT and NT. It was demonstrated that L-arginine/NO promoted apoptosis in pulmonary smooth muscle cells and thereby prevented pulmonary vascular remodeling to a certain extent.

In this paper, the CPE inhibition test was used to detect the antivirus effects, and the apoptosis effects on HeLa cell was studied by AO/EB staining method and DNA agarose electrophoresis. The results showed that the oligo-peptide could inhibit PRV infecting cells. At the same time, the effect had a dose and time dependent effect. The higher the concentration was, the smaller the CPE degree was, and the lowest CPE occurred when treated for 72 h. It verified that oligopeptide could lead to apoptosis of HeLa cell. The apoptotic effect was dose dependent. The apoptotic rates of HeLa cell in the 1.5mg/mL, 0.75 mg/mL group were 60.20% and 48.12% respectively.

The distribution of vessels in the oviducts were studied in 20 Beijing ducks. The results are as follows: The arteries suppling oviduct of the Beijing ducks contained oviductalis cranialis,media, caudalis and vaginalis. The veins drainaging oviduct were stretched along the above ateries and the vessels were situated on the left side of the body, but there was no caudal oviductal vein. The anterior oviductal artery arose from the pubic artery of the left external iliac artery and distributed to the infundibulum and the magnum of the oviduct. The middle oviductal artery arose from the left caudal renal artery and distributed to the isthmus and shell gland of the oviduct. The caudal oviductal artery arose from the left external pudendal artery or left internal iliac artery and distributed to the caudal part of uterus and the cranial part of vagina. The vaginal artery arose from the left internal pudendal artery of median sacral artery and distributed to the caudal part of vagina.

Systems analysis was used to evaluate the economic benefits of various breeding systems combined by three actual quality meat-type chicken lines. The results showed that the average discounted profits of 6 three-way crossbreeding systems was 92.04 times as much as that of pure-line breeding systems, and the average discounted profits of 6 two-way crossbreeding systems was 1.25 times as much as that of pure-line breeding systems. I×(II×III)_♀system and I×II_♀system had the highest total discounted profits and per commercial chicken profits in all three-way crossbreeding systems and in all two-way crossbreeding systems respectively. Sensitivity analysis showed that sensitivities of the price of commercial chicken, commercial chicken’s feed and meat quality assessment score were higher than that of the other economic parameters. Breeding expenses, price of unqualified eggs, feed-off cost in rearing period, and price of culling hen had a lower sensitivity.

This study aimed to investigate the influence of Glycyl-glutamine on the development of immune functions of Yuehuang chicken, and to investigate its effect on proliferation and secretion of chicken lymphocytes. In experiment one ,360 1-day-old Yuehuang chicken were randomly divided into 4 groups, with 90 birds in each group. Group 1 served as control, while group 2 to 4 were respectively supplemented ad libitum with 100,500 and 1 000 μg/L Gly-Gln via drinking water. On 45 and 80 days of age, 18 birds in each group were slaughtered and the bursa of Fabricius , spleen and thymus were weighted and blood samples were collected. At the same times, 3 birds in each group were selected and lymphocytes from blood and spleen were collected for measuring proliferation and secretion of IL-2 and IL-6. Experiment two was conducted to test the proliferation and secretion of lymphocytes when cultured with the addition of Gly-Gln. Lymphocytes from blood and spleen were isolated from 8week-old chicken without treatment of Gly-Gln, and culture in media added with 0, 0.6,1.2 and 2.4 mmol/L Glycyl-glutamine solution respertively. The results showed : (1) Supplementation of Gly-Gln had no significant effect on the development of Fabricius Bursa; but Gly-Gln significantly decreased the thymus indices at 1 000 μg/L level and improved the spleen indices at 500 μg/L level in 80-day-old chickens. (2) The additions of both 500 μg/L and 1 000 μg/L GlyGln significantly increased concentrations of IL-2 and IL-6 in the sera of Yuehuang chicken on 45 and 80 days of age, and enhanced blood lymphocyte proliferation , but inhibited spleen lymphocyte proliferation in 45-day-old chicken.(3) The addition of Gly-Gln at concentration of 2.4 mmol/L in the culture medium significantly enhanced lymphocyte proliferation ,but Gly-Gln did not affect the secretion of IL-2 and IL-6 form cultured lymphocytes.

The samples of minks from several main mink farming areas were detected by the methods of counter immunoelectrophoresis（CIEP）and polymerase chain reaction （PCR）and some data about Aleutian mink disease parvovirus(ADV)infection in farmed mink was obtained. Partial VP2 genes，which include a hypervariable region, of 16 ADV strains isolated were separately amplified by PCR and sequenced. Comparison and analysis of these genes sequences and the related sequences of ADV-G，ADV-Utah1 and ADV-K that reported in the USA and European had been completed. The result shows that : firstly, the closed relationship exists between domestic ADV isolates and foreign ones，and the domestic AD maybe introduced from foreign countries. Secondly, the ADV isolates we obtained have a high genetic diversity. DL1, DL2, MS3 and MS5 may be some new types of ADV because of so obvious differences compared with foreign isolates in the genes sequences.

The antigenic determinants of Vp7 gene of porcine rotavirus A were amplified from cells infected with rotavirus by the reverse transcription-polymerase chain reaction (RT-PCR), and a 981bp cDNA segment was acquived. Using T-A cloning technique, the PCR product was cloned into pGEM-T vector. Cloning plasmid pGEM-T-Vp7 and the prokaryotic expression shuttle vector between E.coli and Lactobacillus pW425t were digested by SacI and KpnI double enzymes, respectively. The purified Vp7 gene was subcloned into the expression vector pW425t. Thus,the recombinant pW425t-Vp7 was constructed, and then was transformed into the competence thyA gene-mutant E.coli X13. Treated lysates of bacterium were loaded directly onto SDS-PAGE, on which approximately 37.07 ku exogenous protein was observed and it was about 15% of the total protein . The protein was further analyzed using Western blot, which indicated that the protein was reactive with the antibody of rotavirus A. The results lay foundation for further studies on the Lactobacillus subunit vaccine and DNA vaccine of Vp7 gene in prevention of porcine rotavirus.

Primers FP/ RP and TaqMan-MGB Probe were designed from sequence of apxIVA gene specific to all serotypes of Actinobacillus pleuropneumoniae. A real-time PCR method was developed for detecting Actinobacillus pleuropneumoniae, which can amplify all strains of APP. The sensitivity is 12fg DNA or 5.1 CFU bacteria. This method can be directly used for detection of APP without DNA extraction.

The effect of lipopolysaccharide（LPS）on the production of NO in primary cultures of rat intestinal mucosa microvascular endothelial cells(RIMEC)was investigated . RIMEC weve in culture exposed to the inflammatory cytokine LPS. Stable NO production, which accumulated in the culture medium without LPS in a linear way for 24 h . LPS induced NO production in RIMEC in a time-dependent manner. These data indicate that LPS triggered endothelial cells activation, the production of NO was enhanced.

To investigate the mechanisms of erythromycin-resisant streptococcus isolated from animals,the minimal inhibitory concentrations(MICs) of pencillin, erythromycin and clindamycin against streptococcus were detected by agar two-fold dilution, the resistance phenotypes of erythromycin-resistant streptococcus were determined by the double disk test, and the presence of mefA, ermB genes were determined by PCR amplification. The results showed that the rate of resistance to penicillin, erythromycin and clindamycin of 111 strains studied were 54.95％，68.47％and 64.86％,respectively. In 76 erythromycin resistant strains, 62 isolates (8158%) were assigned to the cMLS_B phenotype, 5 isolates (6.6%) were M phenotype and 9 isolates (11.84%) were inducibly resistant, expressing the iMLS_B phenotype by the double disk test. The mefA gene was present in all of the strains showing the M-resistance phenotype. Some isolates expressing a cMLS_B phenotype and iMLS_B phenotype were confirmed genotypically by the presence of the ermB gene, but 6 isolates were n’t detected the ermB and mefA gene. Genes coding for both resistance mechanisms were found in one strain. No amplification was detected in all the erythromycin susceptible streptococcus isolates. Erythromycin resistant Streptococcus isolated from animals mediated by ermB was predominant in China. The PCR amplification can be a useful method to rapidly screen the erythromycin resistant strains.