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Purpose: Although shrimp aquaculture in Sri Lanka has mainly been plagued by recurrent outbreaks of White Spot Syndrome Virus (WSSV), recent symptomatic and analytical field data of shrimps were incoherent with typical WSSV infections. As transboundary infection of new diseases is not uncommon in world shrimp aquaculture, the possibility of new diseases established in the country surfaced. Hence, the present study was aimed at evaluating the stock health of shrimps in Sri Lanka for additional six diseases commonly available in the Asian region, namely Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV), Infectious Myonecrosis Virus (IMNV), Taura Syndrome Virus (TSV), Yellow Head Virus (YHV), Acute Hepatopancreatic Necrosis (AHPND) and Necrotizing Hepatopancreatitis Bacterium (NHPB). Research Method: Sampling was performed using broodstocks, postlarvae, cultured Penaeus monodon, wild P. semisulcatus, P. indicus and P. monodon from different locations and broodstock collecting areas in the country. Other crustacean species were also collected as possible carrier species. The presence of pathogenic organisms was identified by Polymerase Chain Reaction using respective IQ 2000TM test kits and a total of 2060 PCR tests were conducted. Findings: Of all the samples tested, no samples were positive for IMNV, TSV, YHV, AHPND and NHPB. However, confirmatory evidence was found in Sri Lanka for the presence of IHHNV with the prevalence of 31.3% in broodstock samples, 24.07% in hatchery-produced postlarvae and 18.03% in cultured shrimps. WSSV was also recorded with a prevalence of 10.34% in broodstock samples and 55.56% in cultured shrimp samples collected. None of the wild collected samples was positive for any of the tested diseases. Originality/value: Reinstating the presence of WSSV in the Sri Lankan shrimp industry, provides confirmatory evidence of the presence of IHHNV in the country, highlighting the possibility of the emergence of new diseases in shrimp farming in Sri Lanka. Also, commonly suggested disease carriers seem to be not the major cause of disease spread during the sampling time. This study, therefore, provides much-needed information about the stock health of shrimps in Sri Lanka. [ABSTRACT FROM AUTHOR]

Feed intake is a crucial factor in promoting aquatic animals' robust and accelerated growth. Recently, plant protein has been used extensively as a replacement for fishmeal in aquaculture diets, potentially causing adverse effects on both feed palatability and animal health. However, incorporating suitable quantities of feed attractants into the diet can enhance feed palatability, stimulate the appetite of aquatic animals, and potentially augment both growth and overall health. A study was conducted to assess the efficacy of various feeding attractant combinations on Penaeus monodon. In this study, these seven diets were formulated consisting of a positive control (labeled as P) based on commercial feed, a negative control (labeled as N) with a low level of feed attractants, and five diets (labeled as A, B, C, D, and E) containing 8% compositional feed attractants. Each of the five attractants (yeast extract, squid visceral powder, fish soluble, squid paste, and shrimp paste) was added in equal amounts to A-E diets. The results showed that compared to the E diet, the A diet significantly improved the final body weight, specific growth rate, weight gain, and feed intake of shrimp and upregulated the expression of pi3k , eif4ela , and raptor in hepatopancreas. Compared to the P diet, the C diet feed significantly increased the activities of glutamate oxaloacetate transaminase and acid phosphatase and upregulated the expression of pi3k , myd88 , and tor in the intestine. In comparison to the N diet, the D diet feed increased the activity of alkaline phosphatase in hemolymph, total superoxide dismutase activity in hepatopancreas, and malondialdehyde content. Additionally, it upregulated the expression of myd88 , pi3k , tor , and ror. Compared to the control group, the feed in the E diet increased the total superoxide dismutase activity in the hemolymph and upregulated myd88 , pi3k , tor , and imd expression levels. Furthermore, C, D, and E diets increased the width of the shrimp's intestinal folds. Regression analysis showed that the weight gain and feed intake increased with the increasing amount of squid paste in the feed and decreased with the addition of shrimp paste. Feed intake increased with the addition of fish-soluble protein and decreased with the addition of yeast extract in the feed. In conclusion, adding attractants (yeast extract, squid viscera powder, fish soluble, and squid paste) to the feed is beneficial for the growth and feeding of shrimp, and it can promote the expression of shrimp intestinal immune-related genes and histological changes, thus promoting shrimp intestinal health. [Display omitted] • The effect of combined feed attractants on growth performance, feed utilization, intestinal organization and immunity of Penaeus monodon. • Dietary A (yeast extract+squid visceral powder+fish soluble+squid paste) positively influenced feed intake and protein synthesis of shrimp. • The addition of squid paste to the diet increased weight gain rate and feed intake, while increasing shrimp paste additions decreased these. [ABSTRACT FROM AUTHOR]

The emergence of diseases such as white spot disease has become a threat to Penaeus monodon cultivation. Although there have been a few studies utilizing RNA-Seq, the cellular processes of host-virus interaction in this species remain mostly anonymous. In the present study, P. monodon was challenged with WSSV by intramuscular injection and survived for 12 days. The effect of the host gene expression by WSSV infection in the haemocytes, hepatopancreas and muscle of P. monodon was studied using Illumina HiSeq 2000. The RNA-Seq of cDNA libraries was developed from surviving WSSV-challenged shrimp as well as from normal healthy shrimp as control. A comparison of the transcriptome data of the two groups showed 2,644 host genes to be significantly up-regulated and 2,194 genes significantly down-regulated as a result of the infection with WSSV. Among the differentially expressed genes, our study discovered HMGB, TNFSF andc-Jun in P. monodon as new potential candidate genes for further investigation for the development of potential disease resistance markers. Our study also provided significant data on the differential expression of genes in the survived WSSV infected P. monodon that will help to improve understanding of host-virus interactions in this species. [ABSTRACT FROM AUTHOR]

Acute hepatopancreatic necrosis disease (AHPND) of shrimps is a bacterial disease, first appeared in China in 2009 and causes mortality up to 100% which usually occurs early (within approximately first 35 days) after stocking shrimp fry of black tiger shrimp, Penaeus monodon (Fabricius) and white leg shrimp, Litopenaeus vannamei (Boone). The purpose of this study was to isolate and identify the pathogenic strain of V. parahaemolyticus causing AHPND in cultured shrimps (P. monodon) using molecular techniques. After a disease outbreak in April 2017, shrimp samples were collected from three different locations of south-west shrimp farming region of Bangladesh viz. Satkhira, Khulna and Bagerhat districts. In this study, three selective media were used for primary isolation of V. parahaemolyticus. Among 28 primary isolates, representative14 isolates were checked for the species-specific detection of V. parahaemolyticus using ldh primers and all of them were found to be positive. The isolates were further characterized to check their AHPND positivity using AP3 and AP4 primers. Four isolates showed positive results for both AP3 and AP4 which indicated that the isolates were AHPND positive. This study also report that all AHPND positive strains showed sensitivity to the antibiotics Tetracycline and Nalidixic Acid. The results of this study will help the farmers and policy makers to make plan to protect shrimps from AHPND and thereby sustain the shrimp farming in Bangladesh. [ABSTRACT FROM AUTHOR]

The study was carried out for 138 days to know the growth and survival rate of P. monodon by applying probiotics in Gazi Fish Culture Ltd. Dacope, Khulna, Bangladesh. Six experimental ponds (4000 m² in size i.e. one acre) were selected of which three were probiotic ponds and three were controlled. After pond preparation, PL15 (average weight of each 4.75±0.09 g) was stocked at the rate of 13 per m² following polymerase chain reaction (PCR) test. CP NASA shrimp feed was used during the study period. Transparency, salinity, pH, dissolved oxygen (DO), temperature, total Ammonia Nitrogen (TAN) were recorded by standard measurements. The average final body weight of the harvested shrimp is 37.67±1.15 g in probiotics ponds and 27.33±0.58 g in controlled ponds and the difference was significant (P < 0.01) between these two productions. The average survival rate was 90.67±1.15 % in probiotic pond and 71.00±3.0 % in controlled pond. The average daily gain (ADG) in weight was 0.27±0.01 g and 0.19±0.01 g in probiotic and controlled ponds, respectively. The result showed that probiotic plays an important role in maintaining water quality parameters, soil quality and health management as well as increases the growth and survival of shrimp. [ABSTRACT FROM AUTHOR]

Penaeus monodon is the mostly exported shrimp in Sri Lanka. This study was conducted to evaluate the effect of gamma irradiation on the microbial, physical and chemical parameters of postharvest P. monodon. Samples from 10 farms were irradiated at 1 kGy, 2 kGy, 3 kGy, 5 kGy and 10 kGy. Total plate count (TPC), yeast and mold count (Y&M), coliform count, Escherichia coli count, color, texture, moisture content, water activity, pH and peroxide value were measured. Average total length and total weight were 12.69 ± 1.42 cm and 15.86 ± 5.70 g respectively. Average TPC of the control was 3.37*104±5.44*103 CFU/g and it was significantly reduced (p < 0.05) by the treatment of 1 kGy–8.58*102±8.09*102 CFU/g. Samples treated with 5 kGy and 10 kGy were almost sterile. Average Yeast and mold count of the control was 9.25*104±1.77*104 CFU/g and it was significantly reduced (p < 0.05) at 1 kGy to 7.42*102±17 CFU/g. At 2 kGy, 3kGy, 5 kGy and 10 kGy the samples became almost sterile. Coliforms and E. coli were not detected in any sample. L*, a*, b*, ΔE and chroma of whole shrimp, peeled shrimp and shrimp muscle were not significantly affected (p > 0.05). Texture, moisture content and water activity were not significantly different (p > 0.05). The pH was significantly different (p < 0.05) and the peroxide values of irradiated shrimps were significantly lower (p < 0.05). Hence, it was concluded that 1 kGy was appropriated for irradiation of postharvest P. monodon. • 1 kGy irradiation dose reduce the microbial growth in Postharvest P. monodon. • Water activity, moisture content and texture were not affected up to 10 kGy. • Colour parameters were not significantly affected by gamma irradiation. • pH of shrimp muscle was significantly affected by irradiation. • Peroxide value was significantly low in the irradiated samples. [ABSTRACT FROM AUTHOR]

Disease outbreak has continued to be a major challenge for shrimp aquaculture industry. In recent years, manipulation of gut microbiota has been shown to improve the health of host shrimp and disease resistance. Therefore, understanding how various factors can shape the gut microbiota of shrimp is crucial for future utilization of gut microbiota as tools for disease controls. The salinity of the rearing environment can potentially affect shrimp gut microbiota as well as the host-microbe interactions. The effects of salinity adaptation on intestinal microbiota and transcriptomes of juvenile black tiger shrimp Penaeus monodon were examined in this experiment. Intestinal microbiota and transcriptomic profiles from juvenile black tiger shrimp of the same cohort adapted to three different salinity levels were examined using 16S rDNA amplicon sequencing and RNA sequencing, respectively. Shrimp were acclimatized from the original 20 ppt salinity to either 10 ppt or 30 ppt over a period of 10 days, and intestinal samples were collected on Day 0, Day 10, and Day 20 after reaching the target salinity. Across all salinity levels, the dominant phyla composition in the intestine of shrimp was relatively similar with Proteobacteria (83.4%), Bacteroidetes (8.1%), Planctomycetes (3.2%), Verrucomicrobia (2.5%), and Firmicutes (1.5%). The most abundant genus was Vibrio. While it can be found at all salinity levels, a relative abundance of Vibrio was lower at 10 ppt than at higher salinity. A shift toward the higher relative abundance of Vibrio ASVs belonging to the Harveyi clade was observed at higher salinity. On the other hand, the relative abundance of Shewanella was higher at 10 ppt than at higher salinity. Other dominant genera in the intestines not affected by the change in salinity were Pseudoaltermonas and Tenacibaculum. The shift in the rearing water microbiota with different salinity levels was also observed. The most abundant intestinal transcripts responding to different salinity levels based on GO classification were intracellular anatomical structure (cellular component), protein binding (molecular function), and organic substance metabolic process (biological function). Genes involved with stress and immune responses were differentially expressed, and correlations between potentially pathogenic Vibrio and genes relating to innate immunity and peritrophic matrix were observed. The results confirmed the influence of rearing water salinity on both the intestinal microbiota and transcriptomes of shrimp. Efforts to shape the microbiota of aquatic animals should take into consideration the rearing salinity to ensure its efficacy. Using multi-omic platform allowed for better understanding of the microbiota and the host-microbe interaction, which will help support the sustainability of aquaculture production. • Salinity effects on microbiota and gene expressions of P. monodon were examined. • Vibrio relative abundance decreased in low salinity environment. • Different ASVs within the Vibrio genus responded differently to salinity change. • Genes involving energy metabolism and immune responses were differentially expressed. [ABSTRACT FROM AUTHOR]

Abstract: This study is to investigate the outbreak of the Taura syndrome (TS) in penaeid shrimps of Thailand. Following the outbreak in 2003, the Taura syndrome virus (TSV) was detected in two closely related penaeids; the Pacific white shrimp, Penaeus vannamei, and the black tiger prawn, Penaeus monodon. Multiple viral infections were detected, we found that the TSV-infected P. vannamei also presented evidence of the White spot syndrome virus (WSSV) as evidenced by histological examination and molecular diagnostic methods. Infections of TSV and WSSV were investigated over a period of ten months between October 2003 and July 2004. TSV infection in shrimps was diagnosed by RT-PCR using the OIE recommended 9195/9992 primers. Positive shrimp gave the expected amplicon of 231 bp. We also amplified and sequenced a fragment of the vp1 gene (354 bp). The pairwise comparisons of vp1 revealed that Thai TSV was phylogenetically related to the Taiwanese strains (98.3% identity). [Copyright &y& Elsevier]

For the past decade, Thailand has been the leading exporter of shrimp and shrimp products to the world market and the income generated contributes substantially to the Thai economy. There are more than one million people employed directly or indirectly by the industry. At present, there is forceful competition due to price differences among major shrimp growing countries and due to new regulations resulting from consumer demands about product safety and environmental friendliness. In addition, various new disease threats have emerged, making management of shrimp cultivation ponds more complex. In the face of these pressures, Thailand has succeeded in maintaining its position as the leading exporter of cultivated shrimp. This paper describes the strategies that have evolved to fuel this success. Changes in the government's role, public policy and support mechanisms, particularly via the industry cluster approach, are considered to be important driving factors. [ABSTRACT FROM AUTHOR]