Table of Content

17 August 2023, Volume 48 Issue 4

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Research Progress on Strategies of Reducing Methane Emission from Ruminants

DIAO Qiyu，JIA Peng

2023, 48(4):  1-6.  DOI: 10.19978/j.cnki.xmsy.2023.04.01

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Global warming has accelerated the melting of glaciers，increased the frequency and intensity of extreme weather，and damaged ecosystems. Greenhouse gases emitted by livestock play a crucial role in global warming. The sixth assessment report of the United Nations Intergovernmental Panel on climate change has pointed out that methane emission reduction is the fastest and necessary way to mitigate global climate change. Methane emissions from ruminants account for nearly one?third of anthropogenic methane emissions，and cause 3%?13% of dietary energy loss. Therefore，this paper will review the methane emission reduction measures of ruminants.

Effects of Cyclophosphamide at Different Doses on Immunosuppression of Chicken Bursa of Fabricius

LI Bingxin1 ，LI Wanyan1 ，CAO Nan1 ，YANG Baohe2 ，YUAN Mingfeng2 ，FU Xinliang1 ，CHEN Wenbin1 ，TIAN Yunbo1 ，HUANG Yunmao1 ，XU Danning1*

2023, 48(4):  7-12.  DOI: 10.19978/j.cnki.xmsy.2023.04.02

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The purpose of this study was to explore the effect of different doses of cyclophosphamide（CTX）onyellow chickens were randomly divided into 4 groups（Control group，CTX20 group，CTX40 group，and CTX80 group）with 3 replicates per group and 10 in each replicate. All groups were fed with basic diet. The chickens in the CTX20，CTX40，and CTX80 groups were intramuscularly injected with 20，40，and 80 mg/kg BW of CTX at 19，20， and 21 days of age，and the control group was injected with the same amount of normal saline. Seven days after the last injection，15 chicks from each group were randomly selected to collect the bursa of Fabricius and serum for histological observation，Tunel，real ? time fluorescence quantitative PCR，and ELISA detection. The histological results showed that CTX treatment could induce the increase of space between the nodules of the bursa of Fabricius， the decrease of cell density in the medullary tissue，fibroplasia in the medullary region，the dissolution of the nucleus， the pyknosis of the nucleus，and the increase of necrotic cells. The Tunel test results showed that CTX could induce apoptosis of bursa cells（P<0.05），and the apoptosis rate in the CTX40 group was more than 35%. The results of real? time fluorescence quantitative PCR showed that the apoptosis ? related genes expressions of Bcl ? 2 and NF ?κB were significantly decreased，and the mRNA expressions of TNF?α and Caspase3 were significantly increased in the bursa of Fabricius by CTX treatment（P<0.05）. The results of serum ELISA showed that compared with the control group， the expression level of TNF?α and IFN?γ was significantly increased，and the expression level of IL?2 and IL?6 was significantly decreased（P<0.05）. These results indicate that the immunosuppression model of the chicken bursae of Fabricius was successfully constructed in this study，and 40 mg/kg CTX had the best effect. the immunosuppression of the bursa of Fabricius in Lingnan yellow chickensand to provide an animal model reference for further research on how to improve the immunity of the bursa of Fabricius. In this study，120 1?day ?old Lingnan

Effects of Different Temperatures on Viability and Sporulation of Oocysts from Eimeria Tenella

LIN Xuhui1# ，ZHU Yibin1# ，GUO Suyin3 ，QI Nanshan1 ，GUO Zhaowen3 ，LI Juan 1 ，YAN Zhuanqiang 2 ，YIN Lijuan2 ，LI Ruhong3 ，LIU Zuozheng4 ，LV Minna1 ，LIAO Shenquan1，2* ，SUN Mingfei1*

2023, 48(4):  13-19.  DOI: 10.19978/j.cnki.xmsy.2023.04.03

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Temperature is an important factor affecting the sporulation and viability of avian coccidia oocysts. In this study，the effects of different temperatures on the sporulation of Eimeria tenella unsporulated oocysts and the viability of sporulated oocysts were investigated by monitoring the sporulation rate of avian coccidia oocysts，intestinal lesions and oocyst production. The results showed that there was no significant change in the oocyst sporulation activity compared to be treated at -80 ℃ for 30 min，and at -40 ℃，-20 ℃，0 ℃，4 ℃，10 ℃，28 ℃，40 ℃，50 ℃ for 30 min or 1 h respectively，but the oocyst sporulation activity was inhibited after administrated at -80 ℃ for more than 1 h，- 40 ℃ or - 20 ℃ for more than 48 h，and 60 ℃ for more than 30 min. The sporulated oocysts were killed by exposure to liquid nitrogen for 2 min，or at -80 ℃ or higher than 50 ℃ for more than 1 h，whereas sporulated oocysts remain viable at -20 ℃ for 1 to 12 h or at 50 ℃ for 30 min. This study provides data support for the storage conditions of avian coccidia oocysts，and has certain research significance for the prevention and treatment of avian coccidiosis.

Study on the Antioxidant Activity of Fermented Soybean Meal and Its Effects on Growth Performance of Lates Calcarifer

TANG Xinggang1 ，GUO Weigan1 ，YUAN Minggui1 ，SUN Kaihui2 ，WANG Xiaoshan2 ，XIANG Rong1，3*

2023, 48(4):  20-24.  DOI: 10.19978/j.cnki.xmsy.2023.04.04

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This study aimed to evaluate the antioxidant activity of water and alcohol extracts of soybean meal andwas better than that of soybean meal（P<0.05）. The weight gain rate，feed??gain ratio，hepatosmatic index，and meat?? fat ratio of dietary supplement with fermented soybean meal group were better than those of the control group，and 2.5% group was the best. fermented soybean meal，and its efffects on growth performance and feed efficiency of Lates calcarifere. For animal experiments，Lates calcarifer in 4 groups were fed the basal diet supplement with 0%（control group），0.5%，1.25%， and 2.5% fermented soybean meal，with 5 replicates per group and 10 fish per replicate. Natural light was used in feeding environment and the temperature was kept at 25~40 ℃，feeding twice daily（9:00 and 18:00）until full for 12 weeks. The results showed that DPPH scavenging rate of water extract and alcohol extract of fermented soybean meal

Study on the Biological Characteristics of Different Generations of Porcine Pseudorabies Live Vaccine (Bartha􀆼 K61 Strain，Cell Line Origin) in Swine Production

QIU Chengwen1 ，LAI Yuehui1* ，QI Dongmei1 ，WU Wenfu1 ，HOU Gaowei1 ，ZHOU Xiaomin1 ，CHEN Jian1 ， XU Shaozhu1 ，ZHANG guo li1 ，CHEN Jiankai1，2 ，ZHANG Pu1 ，2 ，ZENG Yintao1

2023, 48(4):  25-29.  DOI: 10.19978/j.cnki.xmsy.2023.04.05

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To study the biological characteristics of different generations of porcine pseudorabies live vaccinetemperature of piglets in the immune group were normal after post ?infection with PRV GD1 strain；while the body temperature of piglets in the control group was increased after post ?infection with PRV GD1 strain，and all of them became ill and died. These results indicated that the different generations of porcine pseudorabies live vaccine（Bartha? K61 strain，cell line origin）production virus seeds were safe and maintained good immunogenicity to piglets. （Bartha ? K61 strain，cell line origin）production virus seeds，the porcine pseudorabies live vaccine（Bartha ? K61 strain，cell line origin）basic virus seed F7 was continuously passaged to F13，and six generations of PRV F8—PRV F13 were inoculated with piglets for safety test，and three generations of PRV F8、PRV F10 and PRV F13 were inoculated with piglets for immunogenicity test. The results of the safety test showed that the spirit，appetite，and body temperature of piglets were normal during the observation period after each generation of production virus seeds were inoculated on the neck muscles；the results of the immunogenicity test showed that the spirit，appetite，and body

Identification and Antimicrobial Test of Bacillus Velezensis

ZHOU Shuzhen1 ，GU Zhichun1 ，ZHANG Ruixue2 ，LIAO Jiedan3 ，XIE Zhiheng 1 ，ZHANG Xing2 ， GU Wanjun3 ，HUANG Liangzong3*

2023, 48(4):  30-34.  DOI: 10.19978/j.cnki.xmsy.2023.04.06

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In this study,sequencing identification，drug sensitivity testing，and antibacterial assays were conducted on six Bacillus velezensis strains isolated from diverse sources. The results indicated that the 16S rDNA sequences of these six isolates were positioned within the same genetic evolutionary branch of Bacillus velezensis，and sensitivity to seven selected antimicrobial drugs was exhibited. Bacteriostatic effects against both Staphylococcus aureus and Escherichia coli were demonstrated for the six strains and their metabolites. The bacteriostatic intensity of the samples followed the order of Bacillus velezensis liquid, supernatant，and filtrate.

Research Progress of Infectious Laryngotracheitis Vaccines

XU Shaozhu，ZHANG Guoli，QIU Chengwen，KUANG Zhenjie，WU Yanhua，LU Liping，QI Dongmei*

2023, 48(4):  35-41.  DOI: 10.19978/j.cnki.xmsy.2023.04.07

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Infectious Laryngotracheitis（ILT）is a viral respiratory infection of chickens caused by the Infectious Laryngotracheitis Virus（ILTV）. ILT is still a serious avian virus disease to susceptible chickens，especially in the intensive poultry farming areas. ILT is clinically manifested as acute type and mild type，the acute type has high morbidity and mortality，while the mild type has low mortality but increasing infection in intensive poultry farming areas. ILT can cause death and decreased egg production，and lead to severe economic to the poultry industry. At present，ILT has been well controlled in intensive poultry farming areas through comprehensive prevention and control measures combining vaccination and biosafety. In this paper，we reviewed the commercialized attenuated live ILT vaccines and recombinant virus vector live vaccines in many countries，as well as the new ILT vaccines under development，such as recombinant virus vector live vaccines，gene ? deletion live vaccines and virus ? like particle vaccines, in order to provide references for better prevention and control of ILT.

Economic Consideration on Post⁃treatment of PRRS Outbreak in Porcine PRRS⁃negative Farms

RAO Mingzhang1 ，WANG Lianxiang1 ，DENG Sujun1 ，CHAO Xingzhou2 ，CHEN Yanshan1*

2023, 48(4):  42-47.  DOI: 10.19978/j.cnki.xmsy.2023.04.08

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The porcine PRRS virus mutates rapidly with multiple strains coexist. Vaccine protection effect for the virus is not ideal. At present，more and more breeding farms eradicate PRRS virus in the herd，but it is difficult to maintain the negative status. This paper reported a a PRRS JXA1?like strain outbreak in a PRRS ?negative breeding farms. Methods of emergency feedback，strengthening biosecurity，and increasing the health care were taken，and the herd was improved. Feedback and other measures can quickly control the disease. When the PRRS negative farm turns positive，veterinarians need to make decisions on prevention，control and eradication from an economic point of view and use the future income to convert to the net present value evaluation method，and the investment income ratio this time is 1: 3.3，indicating that the method of feedback at this time is economically feasible.

Research Progress of Contagious Bovine Pleuropneumonia

XU Bowen1 ，SHAO Jianhong1 ，WANG Yonggang2 ，CHEN Demei3 ，LUO Baozheng1

2023, 48(4):  48-53.  DOI: 10.19978/j.cnki.xmsy.2023.04.09

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Contagious bovine pleuropneumonia （CBPP） is a serious infectious disease in cattle caused byand diagnosis of CBPP were systematically described. Prevention and control suggestions were put forward according to the pathogenesis and epidemic characteristics of the epidemic in order to provide reference for further research， surveillance，control and early warning of bovine infectious pleuropneumonia in China. Mycoplasma mycoides subspecies mycoides. It is one of the important infectious diseases that must be reported by WOAH and recognized as class I animal epidemic disease in China. The disease was introduced into China in the early 20th century and caused outbreaks in many areas of China，resulting in a mass of cattle deaths，seriously affecting the export trade of relevant products，and leading to heavy economic loss. In 1996，China declared the elimination of CBPP，but it was not until 2011 that China was recognized as a CBPP??free country by WOAH. At present，this disease occurs frequently in Africa，Latin America and other regions，seriously affecting the development of local agriculture and animal husbandry，causing huge economic loss. In recent years，CBPP is still reported in the neighboring countries of China，and there is a risk of re??introduction to China. The research and analysis work of CBPP in China has a slow start and progress compared with other countries. Based on the research progress at home and abroad，the pathogenic characteristics，epidemiological characteristics，pathogenic mechanism，clinical characteristics，detection

Research Progress and Control Strategy of Streptococcosis in Fish

LIANG Qiancai1 ，CHEN Nanqing1 ，LI Ling1 ，LI Han2* ，CAO Jizhen2 ，LI Anxing2

2023, 48(4):  54-59.  DOI: 10.19978/j.cnki.xmsy.2023.04.10

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China is a major aquaculture production country. In recent years，aquaculture industry has developed rapidly，but the problem of disease has become increasingly prominent，seriously threatening the healthy development of aquaculture. Among these，Streptococcosis is the most serious. Streptococci can infect a variety of aquatic organisms. The pathogens of streptococcal disease include Streptococcus iniae，Streptococcus agalactiae，Streptococcus parauberis. Typical symptoms of the Streptococcosis include behavioural abnormalities，proptosis，and meningitis. At present，antibiotics are still the first choice for the treatment of Streptococcosis，but long-term use of antibiotics is not conducive to the long- term development of aquaculture. Vaccine is an effective way to prevent and control theStreptococcosis， but there is no approved commercial vaccine. This article will introduce the etiology， epidemiology，clinical symptoms，pathogenesis，and detection technology of streptococcal disease，new strategies， and thinking of the prevention and control of streptococcal disease，in order to provide a reference for the prevention and control of Streptococcosis.

Application of Immune Colloidal Gold Diagnostic Technology in Veterinary

XU Kaihui1 ，LU Likang1 ，HUANG Yuan2 ，CAI Rujian2 ，WANG Xiaohu2 ，CHEN Jing2 ，XIANG Hua2*

2023, 48(4):  60-65.  DOI: 10.19978/j.cnki.xmsy.2023.04.11

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Immune colloidal gold diagnostic technology is an in vitro diagnostic technique using colloidal gold as a tracer marker applied to antigens and antibodies. It has the advantages of rapid response，simple operation，low cost and portability. At present，immune colloidal gold diagnostic technology is widely used in hospitals，laboratories，field and public places on ? site diagnosis. This paper introduces the basic principle，advantages and disadvantages of immune colloidal gold diagnostic technology，and discusses the application research status of two main methods of immune colloidal gold diagnostic technology?immunochromatography and dot immunogold filtration in animal medical diagnosis at home and abroad.

Overview of Five Frequently Used Virus Inactivators

SHI Daqing，XIAO Yongzhen，CHEN Hanlin，CHEN Jinxian，WANG Ling，QI Dongmei，LIN Derui*

2023, 48(4):  66-71.  DOI: 10.19978/j.cnki.xmsy.2023.04.12

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Virus inactivation is the process of using physical or chemical methods to make the virus lose infectivity. The virus inactivation efficiency is often affected by many factors，such as virus characteristics，types of inactivators and the aims of inactivation. The selection of inactivators is usually determined by the characteristics of the virus and its use after inactivation. Vaccine development requires complete inactivation of the virus while maintaining the integrity of the viral protective antigen epitope structure to induce an effective host immune response. Molecular biological detection requires complete viral genome integrity. Therefore，selecting appropriate inactivators to inactivate highly pathogenic pathogens is an important guarantee for subsequent work such as pathogen molecular diagnosis， serological analysis，and vaccine development. At present，more and more virus inactivators are being developed and utilized. In this paper，5 chemical virus inactivators frequently used are selected，namely formaldehyde，β ? propiolactone，guanidium based chaotropic salts，psoralen，hydrogen peroxide，the inactivation mechanism and inactivation characteristics of the aboved virus inactivators，along with the application of inactivated virus are summarized as follows.

Surveillance Data Analysis of Major Animal Infectious Diseases in Zijin County in 2021

DU Liyin1 ，WEN Junfa1 ，DENG Wenqiang1 ，XU Minsheng2，3，4，5 ，LI Chunling2，3，4，5 ， ZHAI Shaolun2，3，4，5 ，LI Yan2，3，4，5*

2023, 48(4):  72-75.  DOI: 10.19978/j.cnki.xmsy.2023.04.13

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In order to understand the epidemiology and the vaccine immunization status of themajor animalZijin County. infectious diseases in the area，including highly pathogenic avian influenza，Newcastle disease，African swine fever， highly pathogenic porcine reproductive and respiratory syndrome，foot and mouth disease，swine fever，swine pseudorabies，brucellosis，and peste des petits ruminants，4978 samples collected from domestic animals in Zijin County in 2021 were tested by molecular and serological methods. The results showed that the domestic animal population has high antibodies against those major animal infectious diseases in Zijin County，and no other major animal pathogens was detected，which indicated that immunization effect and control of animal diseases were good in

Analysis of the Antibodies of Type O and Type A FMD in Large⁃scale Dairy Farms in Qingyuan Fity From 2020 to 2021

HE Shuzhi1 ，ZHENG Jingcheng2 ，TAN Weijun1*

2023, 48(4):  76-78.  DOI: 10.19978/j.cnki.xmsy.2023.04.14

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To understand the immune status of the dairy cows from the large?scale dairy farms in Qingyuan city， and to timely evaluate the sera titers after immunization of type O and type A foot?and?mouth disease（FMD）bivalent inactivated vaccine，large scale blood sampling was performed. From 2020 to 2021，randomized blood sampling was performed in 7 large ?scale dairy farms within 4 counties in Qingyuan city. 30~50 cow sera were collected from each county. Liquid?phase?blocking enzyme?linked immunosorbent assay（ELISA）was used to test the antibodies against type O and type A FMD. The results showed that the protection rate for type O and type A FMD were 96.97%（320/ 330）and 98.18%（324/330），respectively. In conclusion，the overall immunization status of FMD was good in the large?scale dairy farms in Qingyuan city and the dairy cows were well protected.

Risk Analysis of Cross regional Transmission of Animal Epidemics in Meat Production Areas -- A Case Study of Pork Supplement to Shenzhen

GAO Yuepeng

2023, 48(4):  79-84.  DOI: 10.19978/j.cnki.xmsy.2023.04.15

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The domestic outbreak of the African Swine Fever in 2018 has had a profound impact on the pig industry. To optimize the layout of the pig industry and improve the level of animal epidemic prevention and control, the State Council has put forward suggestions for changing the pork supply mode. This paper initially envisaged the possible problems of animal epidemic risk management and control in Shenzhen under the new model of pork supply, explored the introduction of a theoretical model of risk analysis, straighten out the process of animal epidemic risk analysis, and built a trans??regional animal health risk prevention and control system. In the future, the system will play the role of locking core risk control points, issuing animal epidemic risk early warnings, and eliminating specific animal epidemic risks, so as to ensure the quality and safety of deep pork from the source.