Evaluation of biological and economic efficiency of smallholder pig production systems in North Vietnam

This study evaluates smallholder pig production systems in North Vietnam, comparing a semi-intensive system near a town with good market access, where a Vietnamese improved breed has replaced the indigenous pig breed, and an extensive system away from town, where the indigenous breed still prevails. Fieldwork was conducted in 64 households in four villages. Repeated farm visits yielded 234 structured interviews. Data were analysed by linear models and non-parametric tests. Production inputs and outputs were quantified, and feed use efficiency and economic efficiency were assessed. The gross margin was higher for semi-intensive production with the improved breed, while the benefit-cost ratio was higher under extensive conditions with the indigenous breed. The net benefit did not differ between systems. Twenty-four per cent of farmers yielded a negative net benefit. In one village under extensive conditions, live weight output from indigenous sows with crossbred offspring compared positively with the output from semi-intensive production with improved genotypes, but was associated with high inputs, making production inefficient. Results indicate that improved genotypes might not be an efficient production alternative for saving-oriented production with limited resource supply. Suitability of evaluation parameters, farmers' production aims, and factors impacting the production success in different systems are discussed.

Identification and quantification of subsidies relevant to the production of local and imported pig breeds in Vietnam

Livestock diversity contributes in many ways to human survival and well-being, while its loss reduces options for attaining sustainable agriculture and universal food security. The current rapid rate of loss of this diversity is the result of a number of underlying factors. While in some cases changes in production systems and consumer preferences reflect the natural evolution of developing economies and markets, in other cases production systems, breed choice and consumer preferences have been distorted by local, national and international policy. In the context of a widespread threat to local pig breeds in Vietnam, this paper identifies and quantifies the level of agricultural subsidies that are currently contributing to this process of breed substitution. Producer subsidies-which tend to improve the competitiveness of imported breeds and their crosses over local breeds--are shown to be considerable, and mitigating measures are now urgently needed to avoid an irreversible loss of livestock diversity.

Microsatellite Analysis of Genetic Diversity of the Vietnamese Sika Deer (Cervus nippon pseudaxis)

The Vietnamese sika deer (Cervus nippon pseudaxis) is an endangered subspecies of economic and traditional value in Vietnam. Most living individuals are held in traditional farms in central Vietnam, others being found in zoos around the world. Here we study the neutral genetic diversity and population structure of this subspecies using nine microsatellite loci in order to evaluate the consequences of the limited number of individuals from which this population was initiated and of the breeding practices (i.e., possible inbreeding). Two hundred individuals were sampled from several villages. Our data show both evidence for limited local inbreeding and isolation by distance with a mean F(ST) value of 0.02 between villages. This suggests that exchange of animals occurs at a local scale, at a rate such that highly inbred mating is avoided. However, the genetic diversity, with an expected heterozygosity (H(e)) of 0.60 and mean number of alleles (k) of 5.7, was not significantly larger than that estimated from zoo populations of much smaller census size (17 animals sampled; H(e) = 0.65, k = 4.11). Our results also suggest that the Vietnamese population might have experienced a slight bottleneck. However, this population is sufficiently variable to constitute a source of individuals for reintroduction in the wild in Vietnam.

Indomethacin stimulates glucose production in adults with uncomplicated falciparum malaria

In healthy subjects, basal hepatic glucose production is (partly) regulated by paracrine intrahepatic factors. It is unknown if these paracrine factors also influence basal glucose production in infectious diseases with increased glucose production. We compared the effects of 150 mg indomethacin (n = 9), a nonendocrine stimulator of glucose production in healthy adults, and placebo (n = 7) on hepatic glucose production in Vietnamese adults with uncomplicated falciparum malaria. Glucose production was measured by primed, continuous infusion of [6,6-2H2]glucose. After indomethacin, the plasma glucose concentration and glucose production increased in all subjects from 5.3 +/- 0.1 mmol/L to a maximum of 7.1 +/- 0.3 mmol/L (P < .05) and from 17.6 +/- 0.8 micromol x kg(-1) x min(-1) to a maximum of 26.2 +/- 2.5 micromol x kg(-1) x min(-1) (P < .05), respectively. In the control group, the plasma glucose concentration and glucose production declined gradually during 4 hours from 5.4 +/- 0.2 mmol/L to 5.1 +/- 0.1 mmol/L (P < .05) and from 17.1 +/- 0.8 micromol x kg(-1) x min(-1) to 15.1 +/- 1.0 micromol x kg(-1) x min(-1) (P < .05), respectively. There were no differences in plasma concentrations of insulin, counterregulatory hormones, or cytokines between the groups. We conclude that indomethacin administration results in a transient increase in glucose production in patients with uncomplicated falciparum malaria in the absence of changes in plasma concentrations of glucoregulatory hormones or cytokines. Thus, this study indicates that in uncomplicated falciparum malaria, the rate of basal hepatic glucose production is also regulated by paracrine intrahepatic factors.

Blood levels of DDT and breast cancer risk among women living in the north of Vietnam

A positive association has been reported between elevated tissue organochlorines (p,p'-DDT/p,p'-DDE, PCBs, dioxins) and breast cancer in some case-control studies and occupational cohort studies. We previously reported high serum levels of p,p'-DDT and its metabolite p,p'-DDE in women living throughout Vietnam. We report here the results of a small hospital-based case-control study examining the association between blood levels of p,p'-DDT/p,p'-DDE and the risk of invasive breast cancer among residents of the north of Vietnam-an area where insecticides such as p,p'-DDT have been heavily used in the recent past. The study was conducted among patients admitted to a single hospital in the capital city of Hanoi in 1994. Study subjects were 21 women newly diagnosed with invasive adenocarcinoma of the breast, who served as cases, and 21 women of similar age with fibrocystic breast disease, who served as controls. No increase was evident in the relative risk of breast cancer with increasing tertiles of serum concentration of the compounds of interest, even after adjustment for major potential confounders, such as age at menarche, parity, history of lactation, and body weight. These results suggest that recent and past exposure to p,p'-DDT does not play an important role in the etiology of breast cancer among women living in a country with a tropical climate where insecticide use for mosquito control is common.

Glucose production and gluconeogenesis in adults with uncomplicated falciparum malaria

Although glucose production is increased in severe malaria, the influence of uncomplicated malaria on glucose production is unknown. Therefore, we measured in eight adult Vietnamese patients with uncomplicated falciparum malaria and eight healthy Vietnamese controls glucose production (by infusion of [6,6-2H2]glucose) and the fractional contribution of gluconeogenesis (by oral ingestion of 2H2O); glycogenolysis was calculated as the difference between the two. After 20 h of fasting, plasma glucose was 4.7 +/- 0.2 mmol/l in the patients and 4.3 +/- 0.2 mmol/l in the controls (not significant). Glucose production was approximately 25% higher in the patients (16.9 +/- 1.3 vs. 13.4 +/- 0.3 mumol.kg-1.min-1, P = 0.01). Fractional and absolute gluconeogenesis were increased in the patients (approximately 87 vs. approximately 59%, P < 0.001; and 14.6 +/- 1.3 vs. 7.9 +/- 0.2 mumol.kg-1.min-1, P < 0.001, respectively). The contribution of glycogenolysis to total glucose production was decreased in the patients: 2.3 +/- 0.5 vs. 5.5 +/- 0.4 mumol.kg-1.min-1 (P < 0.002). In conclusion, in adult patients with uncomplicated falciparum malaria, glucose production is increased by approximately 25% due to an increased rate of gluconeogenesis, whereas glycogenolysis is decreased. The mechanism by which these changes occur is uncertain. However, counterregulatory hormone and cytokine concentrations were increased in the patients.

Agent Orange and the Vietnamese: the persistence of elevated dioxin levels in human tissues

OBJECTIVES

The largest known dioxin contamination occurred between 1962 and 1970, when 12 million gallons of Agent Orange, a defoliant mixture contaminated with a form of the most toxic dioxin, were sprayed over southern and central Vietnam. Studies were performed to determine if elevated dioxin levels persist in Vietnamese living in the south of Vietnam.

METHODS

With gas chromatography and mass spectroscopy, human milk, adipose tissue, and blood from Vietnamese living in sprayed and unsprayed areas were analyzed, some individually and some pooled, for dioxins and the closely related dibenzofurans.

RESULTS

One hundred sixty dioxin analyses of tissue from 3243 persons were performed. Elevated 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) levels as high as 1832 ppt were found in milk lipid collected from southern Vietnam in 1970, and levels up to 103 ppt were found in adipose tissue in the 1980s. Pooled blood collected from southern Vietnam in 1991/92 also showed elevated TCDD up to 33 ppt, whereas tissue from northern Vietnam (where Agent Orange was not used) revealed TCDD levels at or below 2.9 ppt.

CONCLUSIONS

Although most Agent Orange studies have focused on American veterans, many Vietnamese had greater exposure. Because health consequences of dioxin contamination are more likely to be found in Vietnamese living in Vietnam than in any other populations, Vietnam provides a unique setting for dioxin studies.

Correlation between dioxin levels in adipose tissue and estimated exposure to Agent Orange in south Vietnamese residents

To permit new epidemiologic studies of the effects of dioxin on humans in Vietnam, we evaluated a model for quantifying exposure to Agent Orange (exposure index) based on the residential histories of 27 Vietnamese subjects and on information about spraying from the U.S. Army records (Herbs Tape) and compared this index to the dioxin levels measured in the subjects' adipose tissue. The mean dioxin level was 7.8 ppt, and dioxin and furan isomer profiles were similar to those already reported in industrialized countries. In addition, there was a highly significant correlation between the levels of almost all the isomers, whatever their degree of chlorination. For the group of 27 subjects, we found a Pearson correlation coefficient of 0.36 (P = 0.07) between the dioxin levels and the exposure index after log-transformation of both variables. When the analysis was restricted to the 22 subjects with a positive exposure index, the Pearson correlation coefficient rose to 0.50 (P = 0.02). We conclude that despite the limitations and power conditions of the study, this result is encouraging because it will be useful for future epidemiologic studies in Vietnam.