Postlarvae Quality Research Articles

Technical and scale efficiency of intensive white-leg shrimp (Litopenaeus vannamei) farming in Vietnam: A data envelopment analysis

Intensive shrimp production is a potential pathway to increasing export quantity and meeting Vietnamese national export targets set for the 2020–2030 period. Vietnamese farmers need to efficiently manage their shrimp farming to compete in global markets. This study aims to investigate input- and output-specific technical and scale inefficiencies in Vietnamese shrimp farming practice and their determinants. The research used a survey among 200 shrimp farmers from Ca Mau, Kien Giang, and Soc Trang provinces in Vietnam, and applied a two-stage approach with a Russell-type (input–output) directional distance function for measuring input- and output-specific technical inefficiency, and a bootstrap truncated regression for exploring the determinants of inefficiencies. Results show that main drivers of technical inefficiencies in Vietnamese intensive white-leg shrimp farms are inappropriate management of energy (inefficiency of 32%), seed (inefficiency of 22%) and shrimp yield production (88%). Furthermore, male farmers experienced in shrimp farming, with proper training and applied plastic-lined ponds are generally better in managing pond areas, use of seed, feed, and labor. Technological innovations, better post larvae quality and their stocking management can help to improve shrimp farming performance.

Comparison of growth and reproduction performance of broodstock Pacific white shrimp Litopenaeus vannamei reared in oceanic and brackish water

This study provides a preliminary evaluation of feasibility of brackish water breeding. Shrimps were initially cultured at brackish water. Shrimps were reared at different stages (5, 6, 7 and 8 months, respectively), and 300 female shrimps were selected from each stage for growth at an enhanced salinity of 30 ppt. When the shrimps were sexually mature, the reproductive characteristics (mating rate, egg number and nauplii number) of the broodstock shrimps, quality of nauplii (malformation rate of nauplii) and quality of postlarvae (survival rate and desalination stress) were tested to evaluate of the effects of brackish water (10 ppt) on these shrimps. Oceanic water (30 ppt) for rearing shrimps was used as control group. Histopathological analysis of gonads and hepatopancreases from oceanic and brackish water shrimp was performed. The results showed that shrimps cultured for a maximum of 8 months in brackish water remained sexually mature. There were no significant differences regarding the quality of shrimps in the oceanic water and brackish water. However, the brackish water cultured shrimps were easily adapted to salinity changes. Our results demonstrate the good feasibility of the present scheme, in which the broodstock shrimps were cultured at a salinity of 10 ppt.

Production characteristics of intensive whiteleg shrimp (Litopenaeus vannamei) farming in four Vietnam Provinces

Whiteleg (Litopenaeus vannamei) and black tiger (Penaeus monodon) shrimp are the most common farm-based shrimp species cultured in Vietnam, but there have been few studies of intensive whiteleg shrimp production. The objectives of this study were to describe production characteristics and to identify factors associated with yield in intensive shrimp production systems in Vietnam. This study included data from shrimp farms in four Vietnam provinces, collected from mid-2014 to early 2016. The data included key production characteristics, such as length of production cycle, number and quality of postlarvae (PL) stocked, feed intake, production yield (kg/m2), harvest size (shrimp/kg), average weight and water quality measurements for some of the crops. We report descriptive statistics for the production parameters and findings from two linear mixed models describing the associations of these parameters with two outcomes: production yield and average weight of shrimp. The average stocking density for the 846 crops included in the dataset was 109 PL/m2, average length of production cycle was 92 days, and average production yield was 1.15 kg/m2. The shrimp gained 0.2 g per day, on average, and consumed an average of 0.17 kg of feed, daily/1,000 PL stocked. The linear mixed models indicated that stocking density, stocking month and region were the main predictors for production yield, while water temperature 4 weeks prior and PL quality were the main predictors for the average weight of shrimp, after accounting for the length of production cycle. This study describes baseline production parameters for whiteleg shrimp production in Vietnam.

Uso de probióticos na produção de pós-larvas de camarão-rosa

O objetivo deste trabalho foi avaliar o uso de probióticos na produção de pós-larvas do camarão-rosa (Farfantepenaeus brasiliensis). Utilizou-se o delineamento experimental inteiramente casualizado, com dois tratamentos - uso de probióticos (Bacillus spp.) e controle com uso de antibiótico (eritromicina) - e quatro repetições. Pós-larvas no estágio PL1 foram estocadas em cada parcela experimental (3,0 L) e cultivadas até o estágio PL10. As variáveis de qualidade de água e o desenvolvimento de bactérias do gênero Vibrio, na água de cultivo, foram monitorados ao longo do experimento. Ao final do período experimental, as pós-larvas foram avaliadas qualitativamente e quanto à sobrevivência, ao peso e ao comprimento. Nas variáveis de qualidade de água, apenas o nitrito apresentou valor significativamente maior no tratamento com antibiótico. Para as variáveis peso e comprimento final, não houve diferenças significativas entre os tratamentos. Não foram observadas diferenças significativas entre os tratamentos quanto à qualidade das pós-larvas e à concentração de Vibrio spp. na água. A utilização de antibiótico pode ser substituída pelo emprego de probióticos durante a produção de pós-larvas de F. brasiliensis.

Lactic-acid bacteria increase the survival of marine shrimp, Litopenaeus vannamei, after infection with Vibrio harveyi

This study evaluated the survival, post-larvae quality, and the population of bacteria in Litopenaeus vannamei after the addition of two strains of lactic-acid bacteria (2 and B6) experimentally infected by Vibrio harveyi. Fifteen hundred nauplii were distributed in 20 L capacity tanks with four replicates. The survival of control animals was lower (21%) than that of animals fed with the strains B6 (50%) and 2 (44%). Total bacterial population in the water and larvae, as well as of the Vibrio ssp. in water was not different among the treatments. No difference was observed in the population of Vibrio ssp. between the control larvae (5.5±0.5 log UFC/mL) and that fed with strain 2 (5.4±0.1 log UFC/mL). Shrimp from control and fed with strain 2 showed significantly higher bacterial population than those fed with strain B6 (1.2±0.2 log UFC/mL). It was detected the lower load of Vibrio ssp. bacteria with potential of pathogenicity after feeding with strain B6.Moreover, these larvae showed more active behavior and low number of necrosis in relation to the control group and to that fed with strain 2.