Spatial analysis and characteristics of pig farming in Thailand

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Abstract

Background

In Thailand, pig production intensified significantly during the last decade, with many economic, epidemiological and environmental implications. Strategies toward more sustainable future developments are currently investigated, and these could be informed by a detailed assessment of the main trends in the pig sector, and on how different production systems are geographically distributed. This study had two main objectives. First, we aimed to describe the main trends and geographic patterns of pig production systems in Thailand in terms of pig type (native, breeding, and fattening pigs), farm scales (smallholder and large-scale farming systems) and type of farming systems (farrow-to-finish, nursery, and finishing systems) based on a very detailed 2010 census. Second, we aimed to study the statistical spatial association between these different types of pig farming distribution and a set of spatial variables describing access to feed and markets.

Results

Over the last decades, pig population gradually increased, with a continuously increasing number of pigs per holder, suggesting a continuing intensification of the sector. The different pig-production systems showed very contrasted geographical distributions. The spatial distribution of large-scale pig farms corresponds with that of commercial pig breeds, and spatial analysis conducted using Random Forest distribution models indicated that these were concentrated in lowland urban or peri-urban areas, close to means of transportation, facilitating supply to major markets such as provincial capitals and the Bangkok Metropolitan region. Conversely the smallholders were distributed throughout the country, with higher densities located in highland, remote, and rural areas, where they supply local rural markets. A limitation of the study was that pig farming systems were defined from the number of animals per farm, resulting in their possible misclassification, but this should have a limited impact on the main patterns revealed by the analysis.

Conclusions

The very contrasted distribution of different pig production systems present opportunities for future regionalization of pig production. More specifically, the detailed geographical analysis of the different production systems will be used to spatially-inform planning decisions for pig farming accounting for the specific health, environment and economical implications of the different pig production systems.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0849-7) contains supplementary material, which is available to authorized users.

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Most cited references 40

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Random forests for classification in ecology.

D Cutler, Thomas C. Edwards, Karen Beard … (2007)

Classification procedures are some of the most widely used statistical methods in ecology. Random forests (RF) is a new and powerful statistical classifier that is well established in other disciplines but is relatively unknown in ecology. Advantages of RF compared to other statistical classifiers include (1) very high classification accuracy; (2) a novel method of determining variable importance; (3) ability to model complex interactions among predictor variables; (4) flexibility to perform several types of statistical data analysis, including regression, classification, survival analysis, and unsupervised learning; and (5) an algorithm for imputing missing values. We compared the accuracies of RF and four other commonly used statistical classifiers using data on invasive plant species presence in Lava Beds National Monument, California, USA, rare lichen species presence in the Pacific Northwest, USA, and nest sites for cavity nesting birds in the Uinta Mountains, Utah, USA. We observed high classification accuracy in all applications as measured by cross-validation and, in the case of the lichen data, by independent test data, when comparing RF to other common classification methods. We also observed that the variables that RF identified as most important for classifying invasive plant species coincided with expectations based on the literature.

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Agricultural intensification, priming for persistence and the emergence of Nipah virus: a lethal bat-borne zoonosis

Juliet Pulliam, Jonathan H. Epstein, Jonathan Dushoff … (2011)

Emerging zoonoses threaten global health, yet the processes by which they emerge are complex and poorly understood. Nipah virus (NiV) is an important threat owing to its broad host and geographical range, high case fatality, potential for human-to-human transmission and lack of effective prevention or therapies. Here, we investigate the origin of the first identified outbreak of NiV encephalitis in Malaysia and Singapore. We analyse data on livestock production from the index site (a commercial pig farm in Malaysia) prior to and during the outbreak, on Malaysian agricultural production, and from surveys of NiV's wildlife reservoir (flying foxes). Our analyses suggest that repeated introduction of NiV from wildlife changed infection dynamics in pigs. Initial viral introduction produced an explosive epizootic that drove itself to extinction but primed the population for enzootic persistence upon reintroduction of the virus. The resultant within-farm persistence permitted regional spread and increased the number of human infections. This study refutes an earlier hypothesis that anomalous El Niño Southern Oscillation-related climatic conditions drove emergence and suggests that priming for persistence drove the emergence of a novel zoonotic pathogen. Thus, we provide empirical evidence for a causative mechanism previously proposed as a precursor to widespread infection with H5N1 avian influenza and other emerging pathogens.

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Highly Pathogenic Porcine Reproductive and Respiratory Syndrome, China

Guang-Zhi Tong, Yan-Jun Zhou, Xiao-Fang Hao … (2007)

To the Editor: Since April 2006, a highly pathogenic disease caused by unknown agents and characterized by high fever and a high proportion of deaths in pigs of all ages, emerged in some swine farms in Jiangxi Province, People’s Republic of China. The morbidity rate was 50%–100% and mortality rate was 20%–100%. In the next several months, the disease spread rapidly to most provinces of China. In almost all affected swine herds, the following clinical signs were observed: high and continuous fever, anorexia, red discolorations in the bodies, and blue ears; in the late phase of the disease, diarrhea and other clinical signs might be seen due to the secondary infections. Clinical samples (from lungs, kidneys, liver, and lymph nodes) were collected from animals in different provinces and sent for laboratory diagnosis. DNA and RNA were extracted from the tissue homogenate and PCR or reverse transcription–PCR (RT-PCR) was conducted to detect porcine reproductive and respiratory syndrome virus (PRRSV), classic swine fever virus, porcine circovirus, and pseudorabies virus, respectively ( 1 ). In clinical samples, only PRRSV was found to be the dominant virus (48 of 50 samples were PRRSV positive). PRRSVs were then isolated successfully on MARC-145 cells with an obvious cytopathologic effect, characterized by cell congregation, contraction, and brushing off at passage 2; immunofluorescence assay using PRRSV NP-, M- and GP5-specific monoclonal antibodies confirmed that the isolated viruses were PRRSV ( 2 , 3 ). Full-length genomic sequencing of 1 of the isolates (HuN4 strain) showed extensive amino acid (aa) mutations in GP5 protein and 2 deletions in Nsp2, 1 aa deletion at 482, and 29 aa deletions at 533–561, compared with the previous Chinese isolates CH-1a and BJ-4. The newly isolated PRRSV was used to examine the pathogenicity in 60-day-old PRRSV-free piglets, under closed and biosafety (P2) conditions. Each of the piglets (N = 5) received intranasally 105.0 50% tissue culture infecting dose of the isolated virus propagated in MARC-145 cells ( 4 , 5 ). The animals were kept in separate rooms throughout the experiment. Clinical observations of respiratory signs, behavior, rectal temperature, and coughing were recorded daily. Blood samples were collected every 2 days and tested for PRRSV-specific antibodies by ELISA ( 6 ,7). Tissue samples (from heart, lungs, kidneys, spleen, and lymph nodes) from all animals that died during the experiment were collected and detected by histopathologic examination ( 8 ) and virus isolation. Results showed that the clinical manifestations of all pigs were similar to those that appeared in the field investigation (including high and continuous fever, anorexia, red discolorations in the bodies, and blue ears). The specific antibodies to PRRSV were detected at 8 days postinfection, and the high antibody level lasted until the animal’s death, and all infected pigs died at either 7, 8, 12, 16, or 21 days postinoculation, respectively. Furthermore, viruses reisolated from the dead pigs showed an identical homology with the inoculated PRRSV in genes coding for GP5 and partial Nsp2 (2,535–3,307 nt). The results showed that the emerging PRRSV, characterized by deletions in Nsp2, is highly pathogenic to pigs. To investigate whether the emerging PRRSV was the causative agent of the pandemic diseases on swine farms, an extensive virus survey was conducted. More than 48 samples collected from different swine farms in12 provinces were found to be PRRSV positive by RT-PCR, based on open reading frame (ORF) 5 and Nsp2 (Figure). Sequence analysis of ORF5 and partial Nsp2 showed that these PRRSVs are highly homologous to each other (98.5%–100% for GP5; 98.2%–100% for Nsp2) and share the same deletions at the same positions of Nsp2 gene with HuN4 strain. Sequence comparison of ORF5 indicated that the HuN4 strain shares 93%, 86%, and 88% nucleotide identities with CH-1a (Chinese isolate), BJ-4 (Chinese isolate), and VR2332 (American isolate), respectively. All the newly isolated PRRSVs belong to the North American type. Figure Geographic distribution of porcine reproductive and respiratory syndrome viruses (PRRSVs) examined in the study. Shaded areas indicate the provinces where the PRRSVs characterized by deletions in Nsp2 were detected. Although the cause of the emerging pandemic disease of pigs with a high proportion of deaths in 2006 is unknown, we found high correlation between PRRSV isolation rate and the diseased pigs. The regression test in its natural animal showed that the newly isolated PRRSV was much more virulent than earlier PRRSV isolates. Also, sequence analysis demonstrated a substantial diversity from the PRRSVs isolated during 1996–2005. Further study is needed to answer the question: What role did the newly isolated PRRSV play in the 2006 outbreaks on many of the swine farms in China?

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Author and article information

Contributors

Weerapong Thanapongtharm: weeraden@yahoo.com

Catherine Linard: linard.catherine@gmail.com

Pornpiroon Chinson: pornpiroonc@dld.go.th

Suwicha Kasemsuwan: fvetswk@ku.ac.th

Marjolein Visser: Marjolein.Visser@ulb.ac.be

Andrea E. Gaughan: aegaughan@gmail.com

Michael Epprech: michael.epprecht@cde.unibe.ch

Timothy P. Robinson: t.robinson@cgiar.org

Marius Gilbert: mgilbert@ulb.ac.be

Journal

Journal ID (nlm-ta): BMC Vet Res

Journal ID (iso-abbrev): BMC Vet. Res

Title: BMC Veterinary Research

Publisher: BioMed Central (London )

ISSN (Electronic): 1746-6148

Publication date (Electronic): 6 October 2016

Publication date PMC-release: 6 October 2016

Publication date Collection: 2016

Volume: 12

Electronic Location Identifier: 218

Affiliations

[1 ]Department of Livestock Development (DLD), Bangkok, 10400 Thailand

[2 ]Lutte biologique et Ecologie spatiale (LUBIES), Université Libre de Bruxelles, Brussels, 1050 Belgium

[3 ]Fonds National de la Recherche Scientifique (FNRS), Brussels, 1050 Belgium

[4 ]Faculty of Veterinary Medicine, Kasetsart University, Kampangsaen Campus, Nakornpatom, 73140 Thailand

[5 ]Research Unit of Landscape Ecology AND Plant Production Systems (EPSPV), University of Brussels, 1050 Brussels, Belgium

[6 ]Department of Geography and Geosciences, University of Louisville, Louisville, 40292 USA

[7 ]Centre for Development and Environment (CDE), Country office in the Lao PDR, Vientiane, 6101 Lao PDR

[8 ]Livestock Systems and Environment (LSE), International Livestock Research Institute (ILRI), Nairobi, 30709 Kenya

Article

Publisher ID: 849

DOI: 10.1186/s12917-016-0849-7

PMC ID: 5053203

PubMed ID: 27716322

SO-VID: f670502e-9b7b-4a80-a12b-6bbf492f39fb

License:

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

History

Date received : 23 October 2015

Date accepted : 30 September 2016

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ScienceOpen disciplines: Veterinary medicine

Keywords: intensive pig farm,sustainable development,spatial distribution,random forest,two-part model

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ScienceOpen disciplines: Veterinary medicine

Keywords: intensive pig farm, sustainable development, spatial distribution, random forest, two-part model

Spatial analysis and characteristics of pig farming in Thailand

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Abstract

Background

Results

Conclusions

Electronic supplementary material

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UN Sustainable Development Goals

Most cited references 40

Random forests for classification in ecology.

Agricultural intensification, priming for persistence and the emergence of Nipah virus: a lethal bat-borne zoonosis

Highly Pathogenic Porcine Reproductive and Respiratory Syndrome, China

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