Economics of Sustainable Intensification of Aquaculture: Evidence from Shrimp Farms in Vietnam and Thailand

There is growing interest in sustainable intensification of aquaculture production. Yet little economic analysis has been done on farm‐level effects of the economic sustainability of production intensification. Data from 83 shrimp farms (43 in Vietnam and 40 in Thailand) were used to identify (through principal component and cluster analyses) 13 clusters of management practices that reflected various scales of production intensity that ranged from 0–1999 kg/ha/crop to 10,000 kg/ha/crop and above, for both Penaeus monodon and Litopenaeus vannamei in Vietnam and Thailand. The clusters identified reflected sets of management practices that resulted in differing yields despite similarities in stocking densities among some clusters. The enterprise budget analysis developed showed that the more intensively managed clusters outperformed the less intensively managed clusters in economic terms. More intensively managed farm clusters had lower costs per metric ton of shrimp produced and were more profitable. The greater yields of shrimp produced per hectare of land and water resources in more intensively managed shrimp farms spread annual fixed costs across a greater volume of shrimp produced and reduced the cost per metric ton of shrimp. Costs per metric ton of shrimp produced decreased from the lowest to the highest intensity level (from US$10,245 at lowest intensity to US$3484 at highest for P. monodon and from US$24,301 to US$5387 for L. vannamei in Vietnam and from US$8184 at the lowest intensity level to US$3817 at the highest intensity level per metric ton for L. vannamei in Thailand). Costs of pond amendments used in shrimp production were particularly high in Vietnam and largely unwarranted, whereas fixed costs associated with the value of land, production facilities, equipment, and labor were sufficiently high in Thailand so that net returns were negative in the long run. Nevertheless, economic losses in Thailand were less at greater levels of intensification. The study demonstrated a clear value proposition for shrimp farmers to use natural resources (such as land) and other inputs in an efficient manner and supports findings from corresponding research on farm‐level natural resource use efficiency. Additional research that incorporates economic analysis into on‐farm studies of sustainable intensification of aquaculture is needed to provide ongoing guidance related to sustainable management practices for aquaculture.     

Energy crops,livelihoods, and legal deforestation: A case study at Phu Wiang National Park,Thailand

Thailand aims to increase the use of renewable and alternative energy by 25% of total consumption under the Alternative Energy Development Plan (AEDP 2012–2021) by 2021, which include outputs from energy crops. This initiative is likely to put pressure on land resources, especially near parks and protected areas. Our study examined energy crop plantations, farmer responses to the AEDP, and community roles in forest protection in four villages adjacent to Phu Wiang National Park, Thailand in 2014. The majority of respondents (80%, n = 50) used their land for rice cultivation, but many villagers increased plantings of sugarcane (54%) and cassava (20%) because of high market demand for energy crops. Only a few examples of agricultural expansion into the national park were observed. Nevertheless, encroachment is likely to occur at this and other national parks as a result of government incentives to plant energy crops and the limited availability of agricultural land. Reliance on community-based management strategies may not be powerful enough for villagers to withstand the pressures of modernization, materialism, and other socioeconomic influences, possibly negating the effect of sustainability. Striking an equitable balance between government policies, community development, and forest protection will be a challenge for resource managers.     

泰国水果干出口机遇与挑战

农业在泰国国民经济中占有重要地位,农产品是泰国外汇收入的主要来源之一。近年来,随着人们生活和饮食习惯的改变,水果干市场发展较为迅速,为了提高泰国水果干在国际市场中的竞争力,通过研究泰国水果干国内外市场现状,采用了SWOT分析法,对泰国水果干的优势、劣势、机会与威胁进行分析,提出相关政策建议。     

Genetic trends in a Holstein × other breeds multibreed dairy population in Central Thailand

Genetic variability and genetic trends for 305-day milk yield (MY), 305-day fat yield (FY), and average 305-day fat percent (FP) were evaluated using monthly test-day records from first-lactation cows collected from 1991 to 2005 in 92 farms located in Central Thailand. Estimates of variance and covariance components and breeding values (EBV) were obtained using a multiple-trait animal model. Fixed effects were contemporary group (herd–year–season), calving age, additive genetic group as a function of Holstein fraction, and non-additive genetic group as function of heterosis effect. Random effects were animal and residual. Program ASREML was used to perform computations. Estimates of heritabilities were 0.38 ± 0.10 for MY, 0.25 ± 0.11 for FY, and 0.22 ± 0.11 for FP. Although the difference between the mean MY for cows in 1991 and 2005 was 324.1 kg, the regression of mean cow EBV for MY on year was 6.5 kg/year. Differences between mean cow EBV for FY and FP in 1991 and 2005 and their corresponding regressions of mean FY and FP on year were all near zero. Similarly, mean EBV for sires and dams of cows also showed near zero trends during these years. A factor contributing to the near complete absence of genetic trends was likely the variety of criteria used by producers to choose sires and to keep dams in addition to EBV (e.g., availability of semen, reproductive ability, adaptation to hot and humid conditions). It also appears that high percent Holstein cows failed to reach their production potential under the management, nutrition, and hot and humid climatic conditions in this tropical region. Changes in nutrition and management would be needed for high percent Holstein cows to show an upward trend in Central Thailand.     

Antibody-ELISA for Trypanosoma evansi: Application in a serological survey of dairy cattle, Thailand, and validation of a locally produced antigen

Trypanosoma evansi is generally considered a mild pathogen in bovines. However, in Asia, acute and chronic signs have been observed in cattle, with high levels of parasitaemia, abortion and death. Investigations in Asian cattle are needed to better understand this epidemiological situation. To generate comparable data at a regional level, development and standardization of an antibody-enzyme linked immunosorbent assay for T. evansi (ELISA/T. evansi) was initiated and applied in an epidemiological survey carried out in dairy cattle in Thailand. A batch of 1979 samples was collected from dairy farms located throughout the country's four regions. Soluble T. evansi antigens initially produced in France were also produced in Thailand for comparison and technology transfer. Screening of 500 samples allowed us to identify reference samples and to determine the cut-off value of the ELISA. Seropositive animals – some of them confirmed by PCR – were found in the four regions, in 12 out of 13 provinces, in 22 out of 31 districts, in 56 farms out of 222 (25%, 95%CI ± 6%) and in 163 animals out of 1979 (8.2, 95%CI ± 1.2%). Estimated seroprevalence in 35 farms ranged between 1% and 30%, and in 21 farms it was >30%. Approximately 25% of survey cattle were exposed to the infection, in various situations. A sub-sample of 160 sera was tested on both antigens. Wilcoxon's (Z = 1.24; p = 0.22) and McNemars's tests (CHI2 = 3.55; p = 0.09) did not show any significant differences, showing that the locally produced antigen is suitable for further evaluation in the surrounding countries. Use of this standardized serological method will broaden knowledge of the prevalence and impact of the disease at the regional level in South-East Asia. Further validation of this ELISA will be necessary in other host species such as buffalo, horse and pig.     

Effects of vertical hedge interval of vetiver grass on erosion on steep agricultural lands

Vetiver grass is widely used to reduce soil erosion and has been applied in many areas of the world. However, studies of the effect of vertical hedge intervals on runoff, soil loss and outflow sediment size distribution under a steep slope area are rare. The vetiver grass system (VGS) with three vertical hedge intervals (0·75, 1·5 and 3 m) and no hedgerow were tested at three land slopes (30, 40 and 50 per cent) under three simulated rainfall intensities (60, 85 and 110 mm h⁻¹). It has been observed that vetiver grass (Vetiveria nemoralis) has great potential for reducing runoff and soil loss by about 38·7–68·6 and 56·2–87·9 per cent, respectively. The vetiver strips delayed incipient runoff and reduced peak runoff rate and steady erosion rate. The land slope affected soil loss but did not have a significant effect on runoff. A narrow vetiver hedge interval slightly reduced runoff and soil loss more than a wider one. The soil loss equation obtained in this study revealed that runoff has a higher effect on soil loss. The median sediment size that passed through the vetiver strip increased with rainfall intensity and was mostly dominated by very fine sand, silt and clay. Copyright © 2009 John Wiley & Sons, Ltd.     

泰国竹类资源现况

泰国是世界主要的竹子分布区之一,现有竹林总面积454 486 hm²,蓄积量1760万m³,物种丰富度1.737,竹子多分布在各自然公园和其他保护区内,依据世界BPG工作组下的记录有17属,72种。介绍了当今泰国竹子的用途、产业、这次他和科学研究等情况。     

泰国榴莲出口潜力研究

水果是泰国重要的农产品经济结构系统的支柱产业,其中榴莲是泰国第二大出口水果。目前在泰国的几乎所有地区都有扩大生产和增加种植面积的发展趋势。虽然榴莲的出口率有所上升,但还没有满足生产市场的需求,特别是在旱季中期的榴莲集中上市季节,通常会发生由于产量过多造成滞销或使榴莲市场价格持续下降的问题。因此,本研究通过采用SWOT分析法,对目前泰国榴莲出口进行研究分析,希望有助于提高泰国榴莲的出口潜力。研究发现,泰国榴莲出口的特色或优势在于:拥有适合的土壤和适宜的气候条件进行榴莲种植,并且有足够的面积扩大榴莲种植,榴莲的单位面积产量高等等;而劣势在于:受到技术知识不足的限制,种植过程中经常受到植物病虫害的影响,并且农民通常使用传统农作方式,生产效率较低等等。     

泰国北部山区有机蔬菜栽培技术及模式初探

利用生物农药和有机肥料,初步探讨泰国北部山区有机蔬菜栽培技术及模式。围绕豇豆—速生叶菜—生菜—豇豆轮作栽培模式,重点介绍3种蔬菜有机栽培过程中土壤消毒、水肥管理、病虫害防治等关键技术环节,形成一套适应泰国北部山区的蔬菜有机栽培技术,为东南亚国家有机蔬菜栽培提供技术参考。