Porcine reproductive and respiratory syndrome （PRRS），caused by porcine reproductive and respiratory syndrome virus （PRRSV），is a major infectious disease leading to the most economically loss in swine industry. Research shows that PRRSV virion invade host cells via three entry mediators (HS,Sn,CD163). PRRSV can inhibit host immune response by inhibiting innate immunity and delaying neutralizing antibody, resulting in persistent infection.Resistance breeding can improve natural immunity, mainly by means of direct selection, indirect selection and transgene. In this paper, the research status of PRRSV pathogenesis and resistance breeding has been reviewed, and the development of novel resistance approaches to PRRSV are also proposed.

This article has reviewed the influence of Lactic acid bacteria on immunological functions including humoral, cellular and mucosal immunity in animal, and the dose effects of Lactic acid bacteria on the modulation of immune responses.

This study aimed to investigate the function of GMPR2 gene which was found in the skin of Liaoning New-breeding Cashmere goat and its relationship with the cashmere fiber growth. Bioinformatics analysis was firstly used, and then positioning analysis was got by using DIG-labeling in situ hybridization technique, and semi-quantitative real-time PCR was used to detect the levels of GMPR2 gene expression in different periods, and then, the RT-PCR was used to detect whether GMPR2 gene was expressed in other organs. Finally, gene expression was affected by different concentration melatonin treatment at different time. The results showed that the gene was really GMPR2 gene, which showed high homology to the Bos taurus GMPR2 gene. The in situ hybridization result showed that GMPR2 had a strong signal in inner root sheath of primary and secondary follicles. Besides, the expression of GMPR2 genes in primary follicles during catagen was the highest (P<0.01), but the expression was not obviously different between anagen and telogen. In addition, RT-PCR analysis showed that GMPR2 gene was only expressed in goat skin, not in liver and heart.The expression quantity of GMPR2 was decreased after melatonin treatment. It was infered that GMPR2 may indirectly regulate the primary and secondry follicles stunted growth.

 The aim of this study was to analyze the association of GHSR gene polymorphisms with body weight and body size traits in goat. Guizhou White goats and Qianbei Ma goats were selected as testing subjects, the DNA pooling was constructed, the direct sequencing technology of PCR products and PCR-SSCP were used to detect the single nucleotide polymorphism of GHSR gene. The result showed that G996A and T1424C were detected in exon 2 and 3′UTR but no SNPs in exon1 and 5′UTR of GHSR gene in these goat breeds, respectively. The G996A was a sense mutation and devided into three genotypes:GG, GA and AA. The study of relationships between genotypes and body weight and body size traits revealed that body weight of individuals of Qianbei Ma goats with genotype GG and GA were significantly higher than those with genotype AA, and chest depth was smaller than those with genotype AA(P<0.05), no significant association of G996A with other indexes was found (P>0.05). Otherwise, the individuals with GG genotype had significantly better body weight, body length and hucklebone width than individuals with genotype AA (P<0.05) in Guizhou White goats. The result indicated that GHSR gene maybe a potential major gene or link to major gene effecting goat body weight, and G996A maybe a candidate molecular marker of MAS.

The complete microsatellite sequence were searched by using MSDB v2.4 (Microsatellite Search and Building Database) in cow (Bos taurus) and sheep (Ovis aries) genomes, and their number, frequency, density and distribution were comparatively analyzed by bioinformatics in the study. Microsatellite (Short tandem repeats, STRs) number in cow and sheep were 806 272 and 682 891 loci, respectively, which respectively account for 4.78‰ and 4.80‰ of whole genome length. The overall STRs number was comparable in each chromosome of cow and sheep. In cow genome, the largest STRs number was found in chromosome 1 followed by chromosome 2, 3, 4, 5 and 6, and the smaller STRs number was in chromosome 25 and 28. In sheep genome, the largest STRs number was also found in chromosome 1 followed by chromosome 2, 3 and chromosome X, and the smaller STRs number was in chromosome 24, 25 and 26. There were highly positive correlation between chromosome length and STRs numbers in cow and sheep genomes (r>0.80, P=0.000). The different STRs repeat types in cow and sheep genomes, mononucleotide repeat type motifs was the most abundance, followed by dinucleotide, trinucleotide, pentanucleotide, tetranucleotide and hexanucleotide repeat types. Repeat copy category of A, AC, AT, AGC, ACG, AAC, AAT, AAAT, AAAC, AAAG were predominate in cow and sheep genomes, whereas repeat motifs of C, CG, AGT, CCG, ACT, AACG, AAGC, AACC, AACT, ACCG, AGCT, AGCG, CCGG and CCCG were rare in cow and sheep genomes.

The aim of this study was to clone and expression IL-1β from Moschus berezovskii for further study on the role of IL-1β in infectious diseases. Moschus berezovskii IL-1β (MBIL-1β) was cloned from peripheral blood mononuclear cells using RT-PCR. The sequence encoding the IL-1β mature peptide was ligated with pET32a(+) vector and expressed in Escherichia coli. The fusion protein was purified by His-Bind Column. Results showed that the length of MBIL-1β was 801 bp, encoding 266 amino acids. Sequence analysis showed that MBIL-1β had a high homology with other ruminants species. The M. berezovskii recombinant IL-1β (MB-rIL-1β) protein was expressed with IPTG induction and mainly in soluble form, the molecular weight was 35 ku. After purified, there was an aimed protein obtained. MTT essay confirmed that the MB-rIL-1β protein could enhance mouse fibroblast cell (L929) proliferation obviously and had biological activities. The result provide a feasible and convenient approach to produce soluble protein MB-rIL-1β with biological activity.

The aim of the present study was to analyze the effect of fixed effects, including herd, parity, sire and days in milk, on fatty acids traits in Chinese Holstein cattle. Totally 816 Chinese Holstein cows from Beijing were selected as experimental population. By the General Linear Model (GLM) procedure of software SAS 9.1 fixed effect model, the effects of the 4 factors on 27 fatty acids traits(myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), and so on) were estimated. The phenotypes of 27 traits were measured by using gas chromatography. The results showed that C16:0, C18:1n9c, C18:0, C14:0 and C18:2 were the main components of milk. Of them, the proportion of C16:0 was the highest(32.65%), SFA∶UFA=1.70∶1. The effects of herd and days in milk on all fatty acids traits were significant (P<0.001), and the effect of sire on main fatty acids traits reached significant level (P<0.05). However, no signifcant effect of parity on fatty acids traits was found (P>0.05). The result indicate that 3 factors, including herd, sire and days in milk, showed significant effects on milk fatty acids traits in Chinese Holstein. The results provide basis for genome-wide association study and gene mapping for milk fatty acids traits in dairy cattle, and are meaningful for milk nutrition improvement.

This study investigated the effect of BMP4 on differentiation of embryonic stem cells (ESCs) to male germ cells. Adherent monolayer culture system was used as a differentiation mode, maleness ESCs were cultured in concentrations of 10,20,30,40 ng·mL^-1 BMP4 to differentiate toward a germ cell lineage. The induced effects were detected by morphology, quantitative polymerase chain reaction(qPCR) and immunocytochemistry. According to the changes in cell morphology and the expression of differential genes, 40 ng·mL^-1 was identified as the suitable concentration of BMP4 on differentiation. During the induction with 40 ng·mL^-1 BMP4, embryoid bodies(EBs) began to appear in 4 d and gradually increased in both size and number in 6-8 d, subsequently some of EBs began to disintegrate into small round cells in 10 d, then a small number of germ cell-like cells could be observed in 12 d, and the number increased in 14 d. The expression of corresponding genes also changed during the induction: the expression level of the ESCs marker genes Nanog, Sox2 decreased significantly (P<0.01), while the expression levels of germ cell-specific genes Stra8, Dazl, integrinα6, c-kit all showed a significant upward trend (P<0.01). BMP4 can promote the expression of the corresponding genes of the germ cells, and has an effect on differentiation of ESCs to male germ cells. The result provides references for differentiation on male germ cells in vitro and theoretical foundation for studying cytogenesis and regulatory mechanism of male germ cells.

 The aim of the study was to investigate the effects of sodium selenite (SS) on in vitro maturation of Yanbian dairy goat oocytes and development of somatic cell nuclear transfer (SCNT). The oocytes were cultured in vitro medium supplemented with different concentrations  (0.0,2.5,5.0，10.0 ng·mL^-1) of SS , then the oocytes maturation rate, intracellular ROS and GSH level were examined. The Yanbian dairy goat mammary gland epithelial cells were as the donor cells for SCNT. The quality and development capacity of SCNT embryos were evaluated with staining. The result showed that 5.0 ng·mL^-1 SS significantly improved the oocytes maturation rate and the SCNT embryos development compentence. The treatment with 5.0 ng·mL^-1 treatment was not only significantly reduced the ROS level but improved the GSH level and the blastocyst cell number. In conclusion, 5.0 ng·mL^-1 SS supplementation in vitro medium can significantly improved the Yanbian dairy goat oocytes maturation rate and SCNT embryos development competence.

 The objective of the present work was to analyze whether cryopreservation could induce the “apoptosis-like” alteration of frozen-thawed boar sperm, and study the molecular mechanism of the fertility reduction of frozen-thawed sperm. Annexin-V/PI combined with the JC-1 fluorescence antibody Kit with flow cytometry (FCM) was used to determine the changes of phosphatidylserine (PS) location and mitochondrial membrane potential (Δψm) of boar sperm before and after cryopreservation with different incubation times . Content changes of “apoptosis” factors（Bcl-2，Caspase-9 and Caspase-3）in boar sperm were validated by immunoblotting analysis. The results showed that the motility of the cryopreserved sperm (54.4%) was lower than fresh sperm (87.9%) (P<0.05), in which the percentage of “apoptosis-like” of sperm with PS dislocation (26.8%) was 21.2% higher(P<0.05) than fresh sperm (5.6%). The cryopreservation  caused an significant increase in the percentage of low Δψm of equilibrated and cryopreserved sperm (P<0.05).Compared with fresh sperm (19.6%), the percentage of sperm with low Δψm increased 59.8% after cryopreservation (P<0.05). The activating levels of apoptotic factors（Bcl-2，Caspase-9 and Caspase-3）in cryopreserved sperm were remarkably higher than the fresh and equilibrated sperm (P<0.05). Present evidences indicated that cryopreservation could induce spermatozoa into the “apoptosis-like” alteration. This study indicated that cryopreservation could not only lead to the dislocation of PS and  reduced the mitochondrial membrane potential, but also stimulate the activities of apoptotic factors（Bcl-2,Caspase-9 and Caspase-3）, induce the frozen-thawed sperm into “apoptosis-like” state in advance, and shorten the survival time of frozen-thawed spermatozoa obviously. This  might be another important reason for low pregnancy rate of frozen-thawed sperm.

This study was conducted to investigate the ovine key sterol-regulatroy genes expression from corpora lutea and different-sized follicles in the later luteal phase. 10 cast ages Hu sheep of proven fertility were used. After estrus synchronization, all ewes were slaughtered on day 12 of estrous cycle, and corpora lutea and different-sized follicles were collected at the same time. The gene expression was determined by real-time PCR method. Compared with follicles ≤2.5 mm in diameter, the follicular very low density lipoprotein receptor (VLDLR), cytochrome P450 (CYP17A1) and cytochrome P450 aromatase (CYP19A1) mRNA expression were significantly increased (P<0.05), however, follicular estrogen receptor 2 (ESR2) mRNA expression was significantly decreased (P< 0.01). There were no significant effects of follicle size on follicular steroidogenic acute regulatory protein (STAR), cytochrome P450scc (CYP11A1), FSH receptor (FSHR), LH receptor (LHR), estrogen receptor 1 (ESR1), low-density lipoprotein receptor (LDLR) and scavenger receptor-BI (SR-BI) mRNA expression, however, ESR1 (P=0.090) and SR-BI (P=0.093) expression trended increase in follicles >2.5 mm. CYP19A1 and CYP17A1 were mainly, as expected, expressed in follicles, however, STAR, CYP11A1, FSHR, ESR2, LHR, ESR1, LDLR, SR-BI and VLDLR genes were preferentially expressed in corpora lutea. In conclusion, sterol-regulatory genes took part in mediating follicular growth and progesterone synthesis of corpora lutea.

This study was conducted to study the regulation effects of L-Arg on the growth and development of pancreas in intrauterine growth retardation (IUGR) piglets. Twelve IUGR piglets and six normal birth weight (NBW) piglets (Duroc×Landrace×Yorkshire) were selected. All piglets were weaned at 7 days of age. Then the IUGR piglets were divided into two groups: IUGR group and IUGR+Arg group, which were supplied with based artificial milk and based artificial milk supplementation with 0.6% Arg, respectively. NBW group was supplied with based artificial milk. Four piglets in each group were slaughtered and sampled at 14 days of age, and the indexes about development of pancreas were measured. The results showed as follows: Pancreatic insulin content, islet area and β-cell mass of IUGR piglets were lower than those of NBW piglets (P<0.05). IUGR significantly reduced the number of islet cells, insulin-positive cell fraction, insulin-positive area and the number of insulin-positive cells (P<0.01). Compared with IUGR control piglets, supplementation with Arg increased body weight and absolute pancreas weight of IUGR piglets (P<0.05), and enhanced pancreatic insulin content, islet area and number of islet cells, as well as β-cell mass, insulin-positive cell fraction and insulin-positive area(P<0.01), which were no significant differences with NBW piglets(P>0.05).The average optical density of IUGR piglets increased by Arg supplementation (P<0.01) and were much higher than that of NBW piglets (P<0.01). These results indicated that IUGR impaired the development of pancreas. L-Arg improved the pancreatic islet structure of IUGR piglets, and increased β-cell mass and insulin synthesis.

The objectives of this study were to investigate the effects of different sources and supplemental dosages of selenium on the piglets growth performance, plasma selenium content and anti-oxidative activities and antioxidant capacity; Three different sources of selenium: Sodium Selenite, Nano-selenium and Selenium Yeast and three dietary supplemental levels at 0.3, 0.5 and 0.7 mg·kg^-1 were used. The piglets fed on a basal diet without external Se sources were used as control group. Six hundreds healthy D×LW×L hybrid piglets at the age of (28±3.5) days, and average initial body weight ((8.50±0.52) kg) were divided into 10 groups with 3 replicates each group and 20 piglets (10 males and 10 females) per replicate and fed with the experimental diets. The trial lasted for 46 days. The results were as follows: ①The difference was not significant in the average daily feed intake of the piglet fed different selenium sources (P>0.05), but the daily gain in the 0.3 and 0.5 mg·kg^-1 nano-selenium groups and 0.5 mg·kg ^-1 yeast selenium group was significantly higher than that in control group (P<0.05), and 0.5 mg·kg^-1 nano-selenium group was significantly higher than that in 0.7 mg·kg ^-1 sodium selenite group (P<0.05). ② The difference was not significant in plasma selenium content of the piglet fed different selenium sources (P>0.05). ③The difference was not significant in the serum MDA level of piglet fed different selenium sources (P>0.05), the serum-AOC level in the 0.5 mg·kg^-1 nano-selenium and 0.5 mg·kg^-1 yeast selenium groups were significantly higher than that in control group(P<0.05), and the GSH-PX levels in 0.5 mg·kg^-1 nano-selenium group was significantly higher than that in the control group (P<0.05).

The objectives of this study were to use the lentiviral vector pTrip-CMV-IRES-pur plasmid to deliver porcine CD163 into a porcine alveolar macrophage (PAM) cell line (CRL-2843), to generate a cell line stably expressing CD163 (designated PAM-CD163), and to evaluate its permissibility for PRRSV infection. The porcine CD163 coding sequences were amplified by PCR from pJET1.2-CD163 plasmid and inserted into downstream of CMV promoter in the lentiviral vector pTrip-CMV-IRES-pur plasmid. Monolayer of 293-T cells were cotransfected with three plasmids psPAX2, pMD2.G and pTrip-CMV-CD163-IRES-pur. The recombinant lentivirus expressing CD163 was harvested in the culture fluid. For transduction, the immortalized PAM cells (CRL-2843) were exposed to lentivirus in the presence of polybrene. The transduced cells were selected with puromycin and single cell colonies were isolated and expanded for PRRSV infection assay. The CD163 gene was transcribed by RT-PCR and the protein was expressed as identified by indirect immunofluorescence assay, Western blot and flow cytometry analyses. A PAM cell line (CRL-2843) stably expressing CD163 (designated PAM-CD163) was susceptible to PRRSV infection with the titer of 10^5.0 TCID₅₀·mL^-1. A PAM cell line stably expressing CD163 was constructed and permissive to PRRSV infection. This cell line could be a valuable tool for PRRSV propagation and PRRSV cellular receptors study.

We have constructed five recombinant plasmids contain modified GP3, GP5 and M genes of PRRSV based on the alphavirus replicon vector, pSCA1, named pSCA-Km5, pSCA-VPm3, pSCA-VPm5, pSCA-VP6 and pSCA-V56. And we studied the expression characteristics in vitro. Expression of proteins was confirmed by western-blotting. In order to evaluate the immunogenicity of the five plasmids in BALB/c mouse model, we detected the antibody, IL-4 and IFN-γ level by ILISA, valued the lymphocyte proliferation activity by MTS staining assay. For the group of pSCA-VPm3, pSCA-VP6, specific lymphoproliferative responses to the PRRSV stimulation were induced in the splenocytes of the immunized mice as demonstrated by MTS staining assay, and antigen specific IFN-γ was detected in the splenocytes by cytokine ELSIA. For the group of pSCA-Km5, pSCA-VPm5 and pSCA-VPm5-PEI, low-level of specific antibody was detected by ELSIA, and antigen specific IL-4 was detected in the splenocytes by cytokine ELSIA. While, the antibody and IL-4 level of the pSCA-Km5 is lower than that of the pSCA-VPm5, which indicated that VP22 gene have transduction capability. The antibody level of pSCA-VPm5-PEI was reduced after 7 weeks, which may because of its toxicity to cells. No neutralizing antibody was detected in the mice. Analysis of the data suggests that the recombined plasmids have well immunity and the capability inducing humoral and cellular immune responses in the mice, indicating that alphavirus replicon-vectored DNA-based vaccine can be potential marker vaccine against PRRS. And the statistics indicate the genes have different ability in inducing immune response.

To investigate the pathogenicity of Salmonella pullorum (S. pullorum) to young chickens, fatal infection experiment was conducted in young chickens by inoculating 12 S. Pullorum, which were chosen from 78 S. pullorum isolates in Eastern China during 2010 and 2012. LD₅₀ and colonization of two virulent S. pullorum isolates was tested in young chickens, while histopathology and immunohistochemistry were applied to analyze pathological lesions and distribution of S. pullorum in tissues at different time point. Results were as follows: Lesions early appeared in tissues at day 3 after inoculation; The most serious lesions appeared during day 7 and 14, and decreased obviously after day 21. The quantity of S. pullorum colonization in different tissues varied during the infection. The two S. pullorum isolates were high pathogenic to young chickens, and different isolates had different ability of colonization and distribution in tissues. This research provided experimental evidence for analyzing the mechanisms and developing vaccine of S. pullorum.

 In order to evaluate the effect of immunoprotection and diagnosis against rabbit Taenia pisiformis cysticercosis by recombinant Tp18 (rTp18) protein, Tp18 gene was screened from transcriptome of adult T. pisiformis, then was cloned and expressed. rTp18 protein was used as immunogen and atopen. The samples were grouped into three experimental groups, including rTp18 protein group, PBS group and adjuvant group. Immunization was performed twice at 14-day intervals. Seven days after the second immunization, each rabbit was experimentally infected orally with 5 000 mature viable T. pisiformis eggs, and sacrificed at 49 days post-infection. The number of cysticercoids was counted. By the end of the experiment, serum was collected for detection of IgG and IgA every week. Repeated trial of rTp18 protein group and PBS group was carried out using identical procedures and conditions. The molecular weight of rTp18 protein is about 32 kDa. rTp18 protein was proved to be well reacted with the positive sera against T. pisiformis from rabbit by Western blotting. Vaccination trials showed that the rTp18 protein induced effective immune protection against T. pisiformis cysticercosis with 95.59% reduction （97.38% reduction in repeated trial） in metacestode burdens of vaccinated rabbits, which was significantly higher than PBS and adjuvant group (P<0.01). IgG was the antibody of humoral immunity. Meanwhile, dot-ELISA was used to diagnose T. pisiformis cysticercosis for rabbits. Based on the results of rabbit necropsy of 169 abattoir rabbit samples, the relative sensitivity and specificity of the dot-ELISA were 90.74% (49/54) and 96.52% (111/115), respectively. These promising results indicate that rTp18 protein is suitable for the development of effective vaccination and diagnositic strategies against cysticercosis in rabbits, providing a foundation for control of T. pisiformis cysticercosis.

To screen the novel candidate vaccine for E. tenella, the genes of EtMA1 and EtMA2 associated with parasites invasion were cloned and the sequences were analyzed. The sequence of EtAMA1 cloned in our laboratory were analyzed by the bioinformatics tool and the technology of comparative genomics, and the gene sequences encoding EtMA1 and EtMA2 were acquared. The EtMA1 and EtMA2 ORF were amplified by RT-PCR from E. tenella (Guangdong strain) merozoites total RNA template. The sequence structures of EtMA1 and EtMA2, and the evolution relationship with other apicomplexan parasites were analyzed by bioinformatics software on line. The result showed that the ORF of EtMA1 and EtMA2 were 1 617 and 1 725 bp in full length, and coding the peptides of 549 and 575 aa in length. The amino acid sequences were highly conserved with E. tenella apical membrane antigen (EtAMA1) and TgAMA1. Both of the EtMA1 and EtMA2 were superfamily proteins of AMA, and which maybe play a key role in parasites invasion of host cells, and both of which will be as novel candidate vaccine for E. tenella.

In this study, p54 protein of African swine fever virus (ASFV) was prokaryotically expressed efficiently, and the expressed p54 protein was tested to be specific to ASFV in ELISA. A sequence-optimized P54 gene was synthesized with reference of P54 gene (E183L) sequence of ASFV Con09/Bzz020 strain, the synthesized ASFV P54 gene was cloned into pET-30c(+) and the recombinant plasmid pET-30c(+)-p54 was obtained. Nucleotide sequence analysis of pET-30c(+)-p54 showed that the synthesized sequence-optimized P54 gene was cloned successfully into pET-30c(+) with the right reading frame. The p54 fusion protein with approximately 20.7 kDa was expressed efficiently, solubly and stably, and easily to be purified with the purity at 900 μg·mL^-1, the expressed p54 protein had the same amino acid sequence as the p54 protein of Con09/Bzz020, the expressed p54 protein was tested to be specific to anti-ASFV serum in Western-blot and had a P/N value of ASFV at 4.67 in ELISA. The results suggested that the expressed p54 protein with high yield was easy to be purified and was specific to anti-ASFV sera, and it could be used for diagnosis of ASFV by ELISA.

The aim of this study was to study the effects of Hoya saponins on immune function and antioxidation of mouse peritoneal macrophages. Saponins were extracted from Hoya stem and leaf. The effects of Hoya saponins on energy metabolism level, phagocytosis capability, nitrous oxide (NO) release, the production of IL-1β, IL-6, TNF-ɑ, glutathione peroxidase (GSH-Px) and Lysozyme (LSZ) activity were determined by using cell culture in vitro method. Results were as follows: Compared to the control group, phagocytosis capability was increased very significantly (P<0.01)at the dose of 5.0-80.0 μg·mL^－1, and energy metabolism level was enhanced very significantly(P<0.01) at the dose of 2.5-320.0 μg·mL^－1, LSZ activity was increased very significantly (P<0.01) at the dose of 10.0-80.0 μg·mL^－1, GSH-Px activity was increased significantly (P<0.05) at the dose of 20.0-40.0 μg·mL^－1, the production of TNF-ɑ was increased very significantly (P<0.01) at the dose of 10.0-80.0 μg·mL^－1, the production of IL-1β was increased very significantly (P<0.01) at the dose of 5.0-40.0 μg·mL^－1, the production of IL-6 was increase very significantly (P<0.01) at the dose of 5.0-20.0 μg·mL^－1, the production of IL-6 was increase very significantly (P<0.01) at the dose of 2.5-160.0 μg·mL^－1. Our results revealed that the Hoya saponins can activate mouse peritoneal macrophages, improve its phagocytosis capability and energy metabolism level, enhance the antioxidant ability, and improve body's immunity.

This study was conducted to investigate the effects of oral administration of N-carbamoylglutamate on growth performance and the endogenous anabolism of arginine of suckling piglets from 7 to 21 days of age. The "Duroc × (Landrace × Yorkshire)" crossbred suckling piglets (n=30, 4-day-old) from 6 litters(same parity, 5 suckling piglets per litter) with similar weight((2.036±0.181) kg) were randomly allocated to five treatments (six replicates each), which were orally administrated at the dose of 0,100,150,200 and 250 mg·kg^-1BW·d^-1 NCG, respectivly. Result: ①Oral administration of 100 and 150 mg·kg^-1 BW NCG significantly increased the average daily gain of suckling piglets compared with the control piglets (P<0.05).②Oral administration of 150 mg·kg^-1BW NCG significantly increased the plasma citrulline content of suckling piglets compared with the other suckling piglets (P<0.05). ③Oral administration of 100,150 and 200 mg·kg^-1 BW NCG significantly increased the activity of carbamoyl phosphate synthase-I in duodenal of suckling piglets (P<0.05). ④Oral administration of 150 mg·kg^-1 BW NCG significantly increased the gene expression of carbamoyl phosphate synthase-I in duodenal (P<0.05); 100 and 150 mg·kg^-1 BW NCG significantly improved the gene expression of carbamoyl phosphate synthase-I(P<0.05) in jejunum and ileum. These results indicated that N-carbamoylglutamate could improve the growth performance and the endogenous anabolism of arginine of suckling piglets.

One pseudorabies virus was isolated from aborted swine fetus of a hoggery of Guizhou province, and was identified. It was named as the PRV Guizhou-DY strain (GenBank accession number JX417716). A lot of experiments had done in the study, e g heat resistance test, acid resistance test and fat-soluble sensitivity test, identification of nucleic acid type, and virus pathogenicity test. The inoculated Vero cells showed the typical cytopathogenic effect when cultured to the second generation, and the stable cytopathogenic effect occurred till the fourth generation. By transmission electron microscopy, the mature virions with envelope were round or ellipse with a diameter of 120 to 180 nm, and viral inclusion bodies arranged like crystal lattice were visible in cell nuclei. The rabbits injected with the isolated virus showed the typical clinical syndrome of pruritus, palsy, opisthotonos and death in the end. Experiments on the virus's physicochemical properties showed that PRV Guizhou-DY Strain was a heat-resistant but not acid and chloroform sensitive DNA virus. Sequence analysis of gE genome showed that PRV Guizhou-DY Strain had some variation compared with GZ-Z1 strain, Fa strain and Ea strain, the homology was 97.6%, 98.9% and 99.4%. And its TCID₅₀ was 10^-9.71·100 μL^-1, PFU was 10⁹·mL^-1. The challenge group pigs developed a fever, and the clinical symptoms are more obvious, neutralizing antibodies began to appear at the 5^th day post infection and at its peak at the 21^st day post infection. This study can provide reference for the study of the viral etiology.