• Journal of Veterinary Science
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• 제23권3호
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• pp.41.1-41.15
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• 2022

Background: Proliferative enteritis caused by Lawsonia intracellularis undermines the economic stability of the swine industry worldwide. The development of cost-effective animal models to study the pathophysiology of the disease will help develop strategies to counter this bacterium. Objectives: This study focused on establishing a model of gastrointestinal (GI) infection of L. intracellularis in C57BL/6 mice to evaluate the disease progression and lesions of proliferative enteropathy (PE) in murine GI tissue. Methods: We assessed the murine mucosal and cell-mediated immune responses generated in response to inoculation with L. intracellularis. Results: The mice developed characteristic lesions of the disease and shed L. intracellularis in the feces following oral inoculation with 5 × 10⁷ bacteria. An increase in L. intracellularis 16s rRNA and groEL copies in the intestine of infected mice indicated intestinal dissemination of the bacteria. The C57BL/6 mice appeared capable of modulating humoral and cell-mediated immune responses to L. intracellularis infection. Notably, the expression of genes for the vitamin B12 receptor and for secreted and membrane-bound mucins were downregulated in L. intracellularis -infected mice. Furthermore, L. intracellularis colonization of the mouse intestine was confirmed by the immunohistochemistry and western blot analyses. Conclusions: This is the first study demonstrating the contributions of bacterial chaperonin and host nutrient genes to PE using an immunocompetent mouse model. This mouse infection model may serve as a platform from which to study L. intracellularis infection and develop potential vaccination and therapeutic strategies to treat PE.

• Journal of Veterinary Science
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• 제21권5호
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• pp.79.1-79.12
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• 2020

Background: Recently, the pork industry of Thailand faced an epidemic of highly virulent strains of porcine reproductive and respiratory syndrome virus (PRRSV), which spread throughout Southeast Asia, including the Lao People's Democratic Republic and Cambodia. Hence, the rapid and on-site screening of infected pigs on a farm is essential. Objectives: To develop the new aptamer as a biosensor for detection PRRSV which are rapid and on-site screening of infected pig. Methods: New aptamers against PRSSV were identified using the combined techniques of capillary electrophoresis, colorimetric assay by gold nanoparticles, and quartz crystal microbalance (QCM). Results: Thirty-six candidate aptamers of the PRRSV were identified from the systematic evolution of ligands by exponential enrichment (SELEX) by capillary electrophoresis. Only 8 out of 36 aptamers could bind to the PRSSV, as shown in a colorimetric assay. Of the 8 aptamers tested, only the 1F aptamer could bind specifically to the PRSSV when presented with the classical swine fever virus and a pseudo rabies virus. The QCM was used to confirm the specificity and sensitivity of the 1F aptamer with a detection limit of 1.87 × 10¹⁰ particles. Conclusions: SELEX screening of the aptamer equipped with capillary electrophoresis potentially revealed promising candidates for detecting the PRRSV. The 1F aptamer exhibited the highest specificity and selectivity against the PRRSV. These findings suggest that 1F is a promising aptamer for further developing a novel PRRSV rapid detection kit.

• Journal of Animal Science and Technology
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• 제64권6호
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• pp.1144-1172
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• 2022

Salmonella enterica serovar Typhimurium isolate HJL777 is a virulent bacterial strain in pigs. The high rate of salmonella infection are at high risk of non-typhoidal salmonella gastroenteritis development. Salmonellosis is most common in young pigs. We investigated changes in gut microbiota and biological function in piglets infected with salmonella via analysis of rectal fecal metagenome and intestinal transcriptome using 16S rRNA and RNA sequencing. We identified a decrease in Bacteroides and increase in harmful bacteria such as Spirochaetes and Proteobacteria by microbial community analysis. We predicted that reduction of Bacteroides by salmonella infection causes proliferation of salmonella and harmful bacteria that can cause an intestinal inflammatory response. Functional profiling of microbial communities in piglets with salmonella infection showed increasing lipid metabolism associated with proliferation of harmful bacteria and inflammatory responses. Transcriptome analysis identified 31 differentially expressed genes. Using gene ontology and Innate Immune Database analysis, we identified that BGN, DCN, ZFPM2 and BPI genes were involved in extracellular and immune mechanisms, specifically salmonella adhesion to host cells and inflammatory responses during infection. We confirmed alterations in gut microbiota and biological function during salmonella infection in piglets. Our findings will help prevent disease and improve productivity in the swine industry.

• Journal of Veterinary Science
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• 제21권2호
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• pp.20.1-20.13
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• 2020

Actinobacillus pleuropneumoniae (APP) causes a form of porcine pleuropneumonia that leads to significant economic losses in the swine industry worldwide. The apxIBD gene is responsible for the secretion of the ApxI and ApxII toxins and the pnp gene is responsible for the adaptation of bacteria to cold temperature and a virulence factor. The apxIBD and pnp genes were deleted successfully from APP serotype 1 and 5 by transconjugation and sucrose counter-selection. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants lost hemolytic activity and could not secrete ApxI and ApxII toxins outside the bacteria because both mutants lost the ApxI- and ApxII-secreting proteins by deletion of the apxIBD gene. Besides, the growth of these mutants was defective at low temperatures resulting from the deletion of pnp. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants were significantly attenuated compared with wild-type ones. However, mice vaccinated intraperitoneally with APP5ΔapxIBDΔpnp did not provide any protection when challenged with a 10-times 50% lethal dose of virulent homologous (APP5) and heterologous (APP1) bacterial strains, while mice vaccinated with APP1ΔapxIBDΔpnp offered 75% protection against a homologous challenge. The ΔapxIBDΔpnp mutants were significantly attenuated and gave different protection rate against homologous virulent wild-type APP challenging.

• 한국동물위생학회지
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• 제46권1호
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• pp.35-45
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• 2023

Pathogenic Escherichia coli is the cause of a wide range of diseases in pigs, including diarrhea, edema disease, and septicemia. Diarrhea caused E. coli may result in significant economic losses, making pathogenic E. coli an important pathogen for the swine industry. This study investigated the prevalence of virulence factor genes, antimicrobial resistance phenotypes, and resistance genes in E. coli isolated from feces of piglets in Korea between 2017 and 2020. As a result, 119 pathogenic E. coli isolates were obtained from 601 fecal samples. The F4 adhesin gene and the STb enterotoxin gene were commonly present in E. coli isolated from diarrhea samples. The dominant virulotypes of isolates from diarrhea samples were STb, Stx2e, and F4:LT:STb. More than 80% of the screened isolates were resistant to ampicillin, sulfisoxazole, chloramphenicol, or tetracycline. To confirm the resistance mechanisms for β-lactam or quinolone, we investigated the genotypic factors of resistance. Each of the ceftiofur-resistant E. coli produced an extended-spectrum β-lactamase encoded by bla_CTX-M-14, bla_CTX-M-27, and bla_CTX-M-55. And all ciprofloxacin-resistant E. coli harbored mutations in quinoloneresistance-determining-regions. In addition, some of the ciprofloxacin-resistant E. coli contained the plasmid-mediated-quinolone-resistance genes such as qepA, qnrB1, or qnrD. This study has confirmed that the F4 fimbria and the STb enterotoxin are the most predominant in pathogenic E. coli isolated from piglets with diarrhea in Korea and there is a great need for responsible and prudent use of antimicrobials to treat colibacillosis.

• Journal of Veterinary Science
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• 제24권4호
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• pp.58.1-58.25
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• 2023

Porcine epidemic diarrhea virus (PEDV) has posed significant financial threats to the domestic pig industry over the last three decades in South Korea. PEDV infection will mostly result in endemic persistence in the affected farrow-to-finish (FTF) herds, leading to endemic porcine epidemic diarrhea (PED) followed by year-round recurrent outbreaks. This review aims to encourage collaboration among swine producers, veterinarians, and researchers to offer answers that strengthen our understanding of PEDV in efforts to prevent and control endemic PED and to prepare for the next epidemics or pandemics. We found that collaboratively implementing a PED risk assessment and customized four-pillar-based control measures is vital to interrupt the chain of endemic PED in affected herds: the former can identify on-farm risk factors while the latter aims to compensate for or improve weaknesses via herd immunity stabilization and virus elimination. Under endemic PED, long-term virus survival in slurry and asymptomatically infected gilts ("Trojan Pigs") that can transmit the virus to farrowing houses are key challenges for PEDV eradication in FTF farms and highlight the necessity for active monitoring and surveillance of the virus in herds and their environments. This paper underlines the current knowledge of molecular epidemiology and commercially available vaccines, as well as the risk assessment and customized strategies to control PEDV. The intervention measures for stabilizing herd immunity and eliminating virus circulation may be the cornerstone of establishing regional or national PED eradication programs.

• Animal Bioscience
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• 제37권4_spc호
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• pp.775-785
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• 2024

Pork production is a significant agricultural enterprise in the United States and Canada. The United States is the third-largest global producer of pork and Canada ranks seventh in pork production. The North American Free Trade Agreement and its successor, the U.S.-Mexico-Canada Agreement, have facilitated trade and integration between the two countries. The majority of production systems are modern and intensive, characterized by large vertically integrated farms using advanced technologies. Both nations benefit from their status as major producers of feed grains, with the United States leading in corn and soybeans, while Canada excels in canola and barley production. The regulatory frameworks for food safety, animal welfare, and environmental stewardship differ slightly, with the FDA and USDA overseeing these aspects in the United States, and Health Canada and the Canada Food Inspection Agency in Canada. The United States and Canada also have well-established distribution networks for pork products, relying on both domestic and international markets. Export markets play a crucial role, with the United States being a major importer of Canadian pigs, and both countries exploring opportunities in Asia. Despite a rise in global demand, domestic pork consumption trends differ, with per capita consumption remaining stable in the USA and declining in Canada. Changing consumer preferences, including a demand for ethically raised and locally sourced pork, may influence production practices. Future trends in pig production include a focus on consumer concerns, sustainability, disease prevention, reduction of antimicrobial use, and advancements in technology. The industry is adapting to challenges such as disease outbreaks and changing regulations, with a strong emphasis on animal welfare. Labor and workforce considerations, along with advancements in technology and automation, are expected to shape the efficiency of pork production in the future.

• 한국축산식품학회지
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• 제24권4호
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• pp.349-354
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• 2004

돼지 골격근 근소포체의 $Ca^{2+}$ 방출통로(calcium - release channel)를 지정하는 ryanodine receptor (RYR1) 유전자의 이상은 악성고열증(malignant hyperthermia, MH)을 유발하고, RYR1 유전자의 점 돌연변이는 돼지 스트레스 증후군(porcine stress syndrome, PSS)과 밀접하게 관련되어 있다. PSS 유전인자 보유 돼지의 90% 이상은 PSE 돈육을 생산하는 것으로 알려져 있어 물퇘지 발생과 생산성 하락으로 경제적 손실을 초래하는 유전적 원인의 PSS 유전자를 검사하여 제거하는 것은 고품질 돼지고기 생산 및 국내 양돈산업의 경쟁력 향상에 매우 중요한 과제라고 할 수 있다. 따라서, 본 연구는 PCR-RFLP 및 PCR-SSCP 기법을 이용하여 PSE 돈육을 생산 하는 PSS 돼지 유전자 진단기술을 개발하고 이를 이용한 국내 종돈 및 교잡 비육돈의 PSS 유전자형 출현빈도를 파악하고자 수행하였다. 돼지 PSS의 원인이 되는 RYR 유전자의 단일염기 돌연변이 (RYR1 C1843T)를 포함하는 DNA 영역을 PCR로 증폭한 후 RFLP 및 SSCP 기법을 이용하여 분석한 결과 동형접합체의 정상 개체(N/N), 이형접합체의 잠재성 개체(N/n)그리고 열성의 돌연변이 유전자를 동형접합체 상태로 갖는 PSS 감수성 개체(n/n)에 각각 특이적인 RFLP 및 SSCP 유전자형이 검출되어 PSS 저항성, 잠재성 및 감수성 개체의 정확한 판별이 가능하였다. 돼지 주요 품종 집단내 PSS유전자형 출현빈도를 조사한 결과 Landrace는 PSS저항성 개체가 57.1%, 잠재성 개체가 35.7%그리고 PSS 감수성 개체의 출현 비율은 7.1%로 분석되었고 L. Yorkshire는 82.5, 15.8 및 1.7%, Duroc은 95.2, 4.8 및 0.0%로 각각 조사되었다. 비육용 교잡돈은 정상 개체가 72.0%, 잠재성 개체가 22.7% 그리고 PSS 감수성 개체는 5.3%였다. 특히, PCR-SSCP 기법을 이용한 RYR1 유전자 돌연변이 검출 방법은 보다 신속 간편하면서도 상대적으로 분석비용이 저렴한 정확성이 높은 PSS 돼지 진단기술로서 대규모 돼지집단 검색이나 RFLP 방법으로 판정이 불확실한 시료의 재검에 효율적으로 이용할 수 있을 것으로 판단된다.

• Journal of Animal Science and Technology
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• 제53권4호
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• pp.333-339
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• 2011

본 연구는 이유 전과 후 돼지 사양프로그램이 성장에 미치는 영향을 구명하고자 수행되었다. 다산차(Yorkshire ${\times}$ Landrace) 모돈과 Duroc 웅돈 사이에서 태어난 총 24복(평균 10.6자돈/복)의 돼지를 3구로 나누어 포유기간 중에 "대조구"는 21일령 이유시까지 대용유와 입붙이 사료를 급여하지 않았고, "최소구"는 포유기 15일째부터 입붙이 사료를 200 gm/복/일 급여했으며, "최대구"는 7일째부터 주간에 7시간 동안 대용유와 입붙이 사료를 무제한으로 급여하였다. 대조구와 최소구로부터 이유된 돼지 중에서 실험구당 68두씩 임의로 선발된 돼지는 각각 2돈방에 수용하고 이유자돈 1, 2 및 3호 사료를 각각 7, 14 및 13일간 급여하였고, 최대구로부터 이유된 같은 수의 자돈에게는 1, 2 및 3단계 사료를 6, 10 및 18일간 급여하였다. 이후에는 모든 실험구에 육성돈 전 후기 사료를 차례로 95 및 135일령까지 급여하였다. 이상의 이유 전과 이유 후전 과정 사양시험은 분할법(split plot) 실험설계 하에 3차례 반복되었다. 포유자돈의 개시체중, 종료체중 및 일당증체량은 최대구와 최소구 대비 대조구 간에 차이가 없었다. 그러나 개시체중은 대조구에 비해 최대구가 0.17 kg 작았지만 개시체중에 보정된 최대구의 종료체중은 대조구에 비해 0.31 kg 컸던 반면 최소구와 대조구 간의 차이는 보정 후에도 거의 변하지 않았다. 자돈기 및 육성기 돼지 성장은 사양프로그램의 영향을 받지 않은 반면 55일령과 135일령 및 6일령 체중은 이유체중과 높은 상관관계가 있었다(각각 r=0.81, 0.57 및 0.76; P<0.001, 0.05 및 0.001). 결론적으로 본 결과는 포유기 초기부터 대용유와 입붙이 사료를 급여하면 체중이 낮은 자돈에 증체 효과가 있을 것이나 포유기 후기에 입붙이 사료를 제한적으로 급여하거나 1, 2단계 자돈사료 급여기간을 수일 연장해서는 자돈기 및 그 이후의 돼지 성장에 영향을 미치지 않을 것임을 시사한다.

• Journal of Animal Science and Technology
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• 제55권3호
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• pp.195-202
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• 2013

본 연구는 돼지 출하체중 증가가 '떡지방' 삼겹살 발생률, 도체등급 및 도체의 품질 특성에 미치는 영향을 구명하기 위해 수행되었다. 본 목적을 위해 85~150 kg 체중 범위의(Yorkshire ${\times}$ Landrace) ${\times}$ Duroc 교잡종 거세돼지와 암퇘지 각각 250두를 도살하여 그 도체를 분석하였다. 거세돼지와 암퇘지의 등지방두께(y; mm)는 각각 다음과 같이 생체중(x; kg)에 선형으로 회귀하였다: y = 0.1827x + 3.4825 ($r^2$ = 0.4671) 및 y = 0.2015x-0.6972 ($r^2$ = 0.4736). 삼겹살의 제 11~12 늑골부 5 cm 폭의 등쪽 반절편의 지방조직 중량비가 55%를 초과하는 경우를 떡지방의 기준으로 설정했을 때 떡지방 삼겹살은 거세돼지에서 10건 발생하였으나 소매상에서 떡지방 삼겹살로 판정된 경우는 없었다. 과중량으로 인해 도체등급이 강등된 도체는 총 101건(20.2%)에 달하였다. $1^+A$ 등급 도체는 다른 모든 등급 도체보다 근내지방도가 높았으나, 근내지방도와 도체 결함 특성을 제외하면 도체등급간 가시적인 품질 상의 차이는 발견되지 않았다. 결론적으로 도체 품질을 충분히 반영하지 못하고 크기만 클 뿐 정상적인 도체에 대해서는 평가절하는 현행 도체등급 판정 기준은 개정되어야 좋을 것이다. 또한 돼지 출하체중을 증가시킬 때 떡지방 삼겹살 발생률은 중요한 고려 사항이 아닌 것으로 사료된다.