Table of Content

24 April 2024, Volume 49 Issue 2

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Research Progress on Novel Goose Astrovirus causing Gout in Goslings

XIANG Yong, TANG Zheng, LI Linlin, XU Zhihong, SUN Minhua

2024, 49(2):  1-7.  DOI: 10.19978/j.cnki.xmsy.2024.02.01

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Goose astrovirus（GAstV）is a newly member of the astrovirus genus discovered recently in China，which mainly affects goslings under 3 weeks of age. The infection rate is as high as 80%，and the mortality rate can beas high as 50%. The goslings infected with GAstV but survived showed growth inhibition and decreased immune level，and were more susceptible to other pathogens. GAstV could be transmitted vertically as well as horizontally by fecal?oral route，and also showed the characteristics of cross ? host transmission. Up to now，due to the lack of commercialized vaccine and other biological products for this virus and the slow progress of the research on its pathogenic mechanism，the scientific formulation and effective implementation of prevention and control measures for this disease still lacks a sufficient theoretical basis and a sound veterinary system，resulting in the grim situation of this disease prevention and control，which has caused great economic losses to the goose industry in China. In this paper，abrief review of the etiology，epidemiology，pathogenicity，immune response and its pathogenic mechanism of GAstV was carried out，with a view to providing a reference for the in ? depth study of GAstV and the preliminary development of preventive and control measures.

Study on Preparation of Roosters Germ Precursor Cells Transplantation Recipients by Injecting Busulfan

2024, 49(2):  8-15.  DOI: 10.19978/j.cnki.xmsy.2024.02.02

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To develop a method suitable for preparing chicken reproductive precursor cell transplant recipient rooster. In this experiment，81 Lingnan yellow roosters with similar body weight and normal reproductive performance were selected for the experiment. The test was carried out in two times. The first test was to calculate the busulfan dosage according to the body weight of the roosters. Direct injection of busulfan into males was evaluated by analyzing blood routine indexes，body weight，testicular weight，mortality，diameter of seminiferous tubules，circumference andarea，and fertility of males on day 15，30，45 or 60 after injection of busulfan. Effects of a method for preparing chicken reproductive precursor cell transplant recipients in the testes of young roosters. The results of test 1 showed that only one rooster with an injection dose of 1.2 mg/kg showed decreased spermatogenic cells in the seminiferous tubules of the testis on the 15th day after the injection of busulfan. Size and weight and fertilization rates were not affected，while other birds showed no significant change compared to the control group. The results of test 2 showed that the size and weight of the testis were significantly reduced on the 15th and 30th days after injection of 30 mg/ unilateral to 50 mg/unilateral busulfan into the testis of roosters. The tissue section analysis after the 30th day showed that the seminiferous tubule membrane in the testis was obtained. The bottom and gland cavity were emptied，and most spermatogonial stem cells in the testicles of males injected with an injection dose of 30 mg/unilateral to 40 mg/ unilateral on the 45th day could be recovered. Fertilization rate decreased significantly，but rooster body weight and blood routine indexes had no significant effect during the whole process. In conclusion，the testicular injection of busulfan can clear endogenous spermatogonial stem cells，and the normal physiological reproductive function of the testis is not affected. The injection dose is 30 mg/unilateral to 40 mg/unilateral on the 30th day after ，the bottom of seminiferous tubule membrane and gland cavity in the testis of rooster are emptied，and this time is the best time to inject reproductive progenitor cells.

Study on Respiratory Heat Production of Chicken

2024, 49(2):  16-22.  DOI: 10.19978/j.cnki.xmsy.2024.02.03

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The metabolism of 250?day?old cocks was studied by means of a 2×2 experimental design of an open return flow respiratory calorimeter for poultry，combined with growth metabolism and fasting metabolism respiratory calorimeter tests. The results showed that the respiratory quotients and caloric production of cell 1 and cell 2 were 1.049，1.104，247.743 and 207.796 kcal/d，respectively，indicating that cell respiration was mainly carbohydrate and fat during feeding. The respiratory quotients and caloric production of cell 1 and cell 2 during hunger strike were 0.855，0.778，184.189 and 155.399 kcal/d，respectively，indicating that the main substrate of cell respiration during hunger strike was protein. Under light condition，the respiratory and heat production of cell 1 and cell 2 were 0.960，0.966，221.198 and 231.643 kcal/d，respectively. Under no light condition，the respiratory and heat production of cell 1 and cell 2 were 0.944，0.916，170.787 and 171.499 kcal/d，respectively. The results showed that chickens showedobvious circadian rhythm，and metabolism was higher in light condition than in dark condition. It can be seen thatunder different lighting conditions，the results of the two cells are similar，and under different feeding conditions，the difference between the two cells is large，but the results in chamber 1 maybe more accurate.

Design and Validation of the Effectiveness on Lentivirus⁃mediated CRISPR/Cas9 Targeting sgRNA for the ACTB Gene

2024, 49(2):  23-29.  DOI: 10.19978/j.cnki.xmsy.2024.02.04

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This study aimed to investigate the cleavage activity of four sgRNAs designed for exon 2 of the chicken β?actin（ACTB）gene using the CRISPR/Cas9 gene editing system. The goal was to establish a framework for targeted knock?in of exogenous genes at the ACTB gene locus. Four sgRNA sequences，specific to the ACTB gene，were designed using awebsite and inserted into lentiviral vectors expressing green fluorescent proteins. Lentiviral fluids were then used to infectachicken fibroblast cell line（DF?1）that stably expresses Cas9 proteins. The knockdown efficiency of the sgRNAs was validated through cell fluorescence expression analysis，T7E1 endonuclease assay，and in vitro activity assay. Three sgRNAs with cleavage activity were identified，providing a solid experimental foundation for subsequent functional validation，gene targeting knock?in on DF?1 cells，and research materials for gene editing in chickens.

Methodology Development of a Locked Nucleic Acid-based Fluorescent Quantitation RT-PCR for Detecting Porcine Epidemic Diarrhea Virus

LI Yan，BIAN Zhibiao，ZHAI Shaolun，LI Chunling

2024, 49(2):  30-36.  DOI: 10.19978/j.cnki.xmsy.2024.02.05

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In this study，aLNA ? based fluorescent quantitation PCR method was developed for the rapid，accurate and trace detection of porcine epidemic diarrhea virus（PEDV）by targeting the M gene. Special primers and LNA ? TaqMan probe were designed according to the M gene，and the reaction conditions have been optimized. The LNA?based fluorescent quantitation PCR method was compared with the conventional TaqMan probe method. Results showed that the detection limit of the method was 3.2 copies/μL，improved by 10 times compared to conventional TaqMan probe method. The method was specific of PEDV and no cross reaction to TGEV，PoRV，and PDCoV. The method had a good repeatability with variation coefficient of intra? and inter?group less than 1%. The method was used to detect 103 clinical samples，the results showed that 47 samples were positive for PEDV，with a positive rate of 45.63%，and the positive coincidence rate with the conventional TaqMan probe PCR assay was 90.38%. This LNA? based fluorescent quantitation PCR method provides a new technical for accurate detection and epidemiological investigation of PEDV.

AComparative Study Between the Effects of Rice⁃duck co⁃ cropping and captivity on the Performance of Hemp Duck

2024, 49(2):  37-40.  DOI: 10.19978/j.cnki.xmsy.2024.02.06

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This study aimed to evaluate and compare the effects of rice?duck co?cropping and captivity on the performance of hemp duck，in order to lay a theoretical basis for the ecological farming of ducks. A total of 400 one? day?old male ducks from a commercial hatchery were randomly divided into two groups：arice?duck co?culture group （density of 30 ducks/m2）and a captive group（density of 10 ducks/m2），with 10 replicates in each group and 20 ducks in each replicate. The experimental duration was 49 days. The 20 ducks were divided into 10 wire floor fences for a total of 200 ducks in captive group，and another 200 were stocked in paddy fields as rice?duck co?culture group. At the age of 49 days，performances including body weight and feed intake were measured. Results showed that the daily gain，daily feed intake and body weight of the rice?duck co?culture group were significantly higher than those of the captive group（P<0.001），while the feed?to?gain ratio of the captive group was significantly higher than those of the rice?duck co?culture group（P<0.001）.In conclusion，the rice?duck co?culture model could improve performance of ducks，reduce feed consumption，and improve economic profit.

Application and Effects of Potassium and Magnesium on Swine Production and Meat Quality

2024, 49(2):  41-45.  DOI: 10.19978/j.cnki.xmsy.2024.02.07

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Potassium and magnesium are indispensable minerals in the growth process of swine. Potassium ions can maintain the acid ? base balance，ion balance，water balance and osmotic pressure balance of cells，and magnesium ions play an important role in sugar metabolism，protein metabolism and fat metabolism. Dietary addition of minerals can improve growth performance and regulate meat quality of swine. In this paper，the effects of dietary potassium and magnesium supplementation on the growth，reproductive and immune performance in swine were reviewed，and the effects of potassium and magnesium on the quality of pork and its regulatory mechanism were discussed in depth，in order to provide theoretical support for the rational application of potassium and magnesium in swine production.

Research Progress on the Effects of Natural Polysaccharides on Inflammatory Bowel Diseases

ZHANG Yingwen，GUO Shining

2024, 49(2):  46-51.  DOI: 10.19978/j.cnki.xmsy.2024.02.08

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Inflammatory bowel disease（IBD）was characterized by persistence and recurrence． The current clinical treatment drugs were ineffective，expensive，and have serious adverse reactions，which causing long ? term distress to patients. Natural polysaccharides have many advantage，such as had a wide range of sources，lower cost， and fewer side effects，which can treat IBD by reducing inflammation，alleviating oxidative stress，adjusting microbial flora，and protecting mucosal barrier. In addition，polysaccharides have been studied as carriers of IBD drugs. However，due to the wide variety and complex structure of polysaccharides，most studies are still in the stage of animal experiments. This current paper mainly discusses the recent research progress of natural polysaccharides in the treatment of IBD，in order to provided more evidences for the further development and utilization of polysaccharides ．

Research Progress on the Antibody Detection Methods for Porcine Pseudorabies Virus

LU Likang1，XU Kaihui1，HUANG Yuan2，CAI Rujian1，2，WANG Xiaohu1，2，CHEN Jing2，XIANG Hua1，2*

2024, 49(2):  52-56.  DOI: 10.19978/j.cnki.xmsy.2024.02.09

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Pseudorabies，also called Aujeszky 's disease，is a highly contagious disease caused by pseudorabies virus (PRV). In the absence of a specific host，pseudorabies virus can invade the body of a variety of mammals， including pigs，cattle，sheep，etc.，which leads to severe clinical symptoms and acute death in susceptible animals. The existence of porcine pseudorabies was first reported in China in the 1950s，and since 2011，new porcine pseudorabies variants have emerged in some areas，resulting in serious economic losses to the pig industry. Although scientists have been working on the design of diagnostic methods and the development of related vaccines， pseudorabies is still widespread in the pig industry，and its discovery in recent years that it also has potential problems for human health has aroused strong concern in the world. At present，pseudorabies vaccine is widely immunized in pig farms in China，so it is very important to detect the antibody level produced by the vaccine after immunization. In this paper，the current antibody detection methods for PRV will be summarized，and their advantages anddisadvantages will be compared and analyzed in order to provide a reference for the selection of antibody detection methods on pig farms.

Research Progress on the STING Signaling Pathway in Different Hosts Disease

2024, 49(2):  57-64.  DOI: 10.19978/j.cnki.xmsy.2024.02.10

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cGAS?STING is an intracellular DNA sensor that activates innate immune responses against invading pathogens and autoimmune diseases. Activation of the STING pathway initiates interferon regulatoryfactor IRF3 and NF?κB. IRF3 can be transported into the nucleus and trigger the expression of ISGs and type I IFNs，leading to the activation of immune cells and migration to target cells. NF ? κBcan drive the production of inflammatory cytokines. cGAS ? STING can lead to the production of proteins that mediate inflammatory responses and plays a unique and critical role in host anti ? pathogen，autoimmune diseases，tumor immunity and aging ? related inflammation. In this paper，the structure and function of cGAS?STING signaling pathway are taken as the starting point，and its regulatory role in different hosts is comprehensively discussed，in order to provide theoretical basis and reference value for the related research of cGAS?STING.

Research Progress on the Meat Embrittlement of Tilapia

2024, 49(2):  65-69.  DOI: 10.19978/j.cnki.xmsy.2024.02.11

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Meat tenderization plays a pivotal role in elevating the palatability of farmed tilapia. Conventionally， the incorporation of Faba beans into tilapia feed has been employed to augment muscle crude fat content，enhance muscle fiber diameter，and bolster muscle resilience，cumulatively leading to a desirable texture. Nonetheless，this approach is not without its challenges，as it can potentially undermine the growth performance of tilapia，induce intestinal mucosal damage，and even culminate in substantial mortality. To date，the specific factor within Faba beans responsible for these effects，and the underlying mechanism by which it exerts its influence on tilapia meat texture， remain enigmatic. In this comprehensive review，we undertake a rigorous comparative analysis of existing research pertaining to the cultivation of tenderized tilapia. This review delves into the intricate interplay between meat quality， growth performance，intestinal health，and immune indicators following the tenderization process. It aims to offer a theoretical reference for further research and practical applications of tilapia tenderization techniques.

Research Progress and Prospect on Water Pollution Control Technology in Waterfowl Farming

2024, 49(2):  70-74.  DOI: 10.19978/j.cnki.xmsy.2024.02.12

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Water is indispensable to the breeding of waterfowl，and the water pollution caused by intensive breeding has a negative impact on the development of waterfowl industry. The bacterial reproducing in aquaculture wastewater usually leads to the increase in the concentration of harmful substances such as bacteria and pathogens， which affects the health and performance of waterfowl. Wastewater treatment in aquaculture is a common practice to improve the above situation. At present，there are several mainstream solutions for wastewater treatment of waterfowl industry，including the addition of photosynthetic bacteria，bacillus subtilis and other ecological agents to the aquaculture water，water purifying agents such as polyaluminum compounds，and change of the breeding mode. This review systematically analyzed the harm of aquaculture wastewater to the health and performances of waterfowl， introduced the research progress of wastewater prevention and pollution control technology in waterfowl farming，and provided insight into the development direction of the integrated prevention and control technology of waterfowl wastewater treatment in the future.

Current Status of Preservation and Utilization for Guangdong Indigenous Livestock and Poultry Genetic Resources

2024, 49(2):  75-80.  DOI: 10.19978/j.cnki.xmsy.2024.02.13

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Livestock and poultry genetic resources are materially fundamental to the initial innovation and development of animal husbandry，and are pivotal means to enhancing the competitiveness of livestock and poultry breeding industry. Guangdong is rich in livestock and poultry genetic resources and has generated a strong comprehensive strength in corresponding breeding industry. Meanwhile，an increasing importance has been attached to the genetic preservation and management in recent years. We here introduced the current livestock and poultry genetic resources in Guangdong with regards to its scale，conservation techniques and methods，construction of preservation system，and major achievements of innovative development and utilization. Thus，the major problems that existed were analyzed，to which constructive solutions were proposed，expectantly providing a reference for the virtuous cycling pattern between preservation and utilization of livestock and poultry genetic resources.

Feeding and Management of Ternary Hybridation Gilts

2024, 49(2):  81-84.  DOI: 10.19978/j.cnki.xmsy.2024.02.14

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The scientific feeding and management of reserve sows has laid a foundation for the long ? term development of pig farms，which is of great significance to realize self?breeding and self?cultivation of pig farms，and improve the comprehensive breeding efficiency. Therefore，it is the premise to improve the production potential of pig farms and one of the basic guarantees for the sustainable and stable production of the pig farms. This paper reviewed the breeding，estrus，disease，and mating management of ternary backup sows，and also summarizes the key points of management of ternary backup sows. It is hoped that it can help pig farms to raise backup sows，and improve the conception rate and childbirth rate，and then improve efficiency.