Juvenile Pacific White Shrimp Litopenaeus Research Articles

Virulence Variation of White Spot Syndrome Virus in Pacific White Shrimp Litopenaeus vannamei

The virulence of seven geographic isolates of white spot syndrome virus (WSSV; genus Whispovirus; China [strain CH1995], Nicaragua [strain N2000], Honduras [strain H2000], Ecuador [strains E-L1999 and E-LT2002], and Mexico [strains M-M2001 and M-LP2001]) was compared using a series of challenge experiments, each lasting 10 d. For each isolate, four quantified dilutions (10(-6), 10(7), 10(-8), and 10(-9)) of a viral inoculum were prepared from WSSV-infected shrimp tissue. Each viral inoculum was injected into 10 specific pathogen-free juvenile Pacific white shrimp Litopenaeus vannamei (0.25-1.50 g); controls received injections of marine crustacean physiological saline (3.2%). The minimum dose of viral inoculum that killed 50% of injected shrimp (LD50) was calculated for dilution, tissue concentration, and viral DNA amount. The CH1995 and M-M2001 isolates were the least virulent, with LD50 values of 10(-6) to 10(-7) of viral inoculum. The isolates could be grouped into three virulence clusters (CH1995 and M-M2001; N2000 and E-LT2002; and H2000, E-L1999, and M-LP2001). Virulence clusters were not altered by LD50 values based on viral DNA concentration, although a slight shifting of order in regards to virulence was seen among the three most virulent isolates (E-L1999, H2000, and M-LP2001). Overall, results indicate that there is a measurable virulence difference among WSSV isolates, which may correspond to geographical region.

Quantitative dietary threonine requirement of juvenile Pacific white shrimp,Litopenaeus vannamei(Boone) reared in low-salinity water

An 8-week feeding trial was conducted to determine the threonine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low-salinity water (0.50–1.50 g L−1). Diets 1–6 were formulated to contain 360 g kg−1 crude protein with fish meal, wheat gluten and pre-coated crystalline amino acids with six graded levels of l-threonine (9.9–19.0 g kg−1 dry diet). Diet 7, which was served as a reference, contained only intact proteins (fish meal and wheat gluten). Each diet was randomly assigned to triplicate groups of 30 shrimps (0.48±0.01 g), each four times daily. Shrimps fed the reference diet had similar growth performance and feed utilization efficiency compared with shrimps fed the diets containing 13.3 g kg−1 or higher threonine. Maximum specific growth rate (SGR) and protein efficiency ratio were obtained at 14.6 g kg−1 dietary threonine, and increasing threonine beyond this level did not result in a better performance. Body compositions, triacyglycerol and total protein concentrations in haemolymph were significantly affected by the threonine level; however, the threonine contents in muscle, aspartate aminotransferase and alanine aminotransferase activities in haemolymph were not influenced by the dietary threonine levels. Broken-line regression analysis on SGR indicated that optimal dietary threonine requirement for L. vannamei was 13.6 g kg−1 dry diet (37.8 g kg−1 dietary protein).

Effect of the Dietary Ratio of Digestible Energy to Crude Protein on Growth and Feed Conversion in Juvenile Pacific White Shrimp Litopenaeus vannamei under Similar Levels of Daily Protein Consumption

AbstractWe evaluated the effect of the dietary ratio of digestible energy (DE) : Crude protein (CP) on growth performance and nutrient utilization in juvenile Pacific white shrimp Litopenaeus vannamei fed various diets with a constant daily protein input. Juveniles (weight = 0.94 ± 0.04 g [mean ± SE]; n = 30) were stocked in an indoor recirculating‐water system (173‐L polyethylene tanks; 20 shrimp/tank) and were assigned to four different treatments. Two treatments consisted of 30% and 40% CP diets (30 isoenergetic [ISO]‐100% and 40 ISO‐75%, respectively) with a constant level of DE (3.28 kcal/g). Two treatments consisted of 30% and 40% CP diets with variable levels of DE (2.70 and 3.6 kcal/g, respectively) that maintained a constant DE : CP ratio of 9 kcal/g of protein (30 ratio [RAT]‐100% and 40 RAT‐75%, respectively). At the end of the 49‐d trial, final weight and weight gain did not differ among the treatments. However, feed conversion ratio (FCR) was significantly lower (P < 0.01) for the 40 RAT‐75% and 40 ISO‐75% groups than for the 30 ISO‐100% and 30 RAT‐100% groups. Final body composition (dry matter, CP, and gross energy) and protein conversion efficiency were not significantly different among the four treatments. However, energy conversion efficiency was significantly higher for the 40 ISO‐75% group than for the 30 ISO‐100% group. This study demonstrates that when the level of energy is appropriate, increasing dietary protein content allows for reduced feed inputs without affecting shrimp growth performance, while actually improving FCR and water quality due to presumably lower wastage of feed.

Partial Replacement of Fishmeal by Lyophylized Powder of the Microalgae Spirulina platensis in Pacific White Shrimp Diets

An eleven-week feeding trial was conducted to evaluate the growth effect of partial replacement of fishmeal by the microalga Spirulina platensis in the diet of juvenile Pacific white shrimp Litopenaeus vannamei (Boone). The results clearly indicate that Spirulina platensis constitutes an effective food ingredient for shrimp. Growth rates of a Spirulina-fed group differed highly significantly (p < 0,001) compared to two groups fed to less suitable diets and were slightly, even though not significantly superior to that based on an optimal commercial reference fish diet. As a side effect, Spirulinafed shrimps showed measurable differences in pigmentation.

Replacement of fish meal in practical diets for the Pacific white shrimp ( Litopenaeus vannamei) reared under pond conditions

Increasing economical and ecological concerns regarding the use of fish meal in diets for marine shrimp have led to the development of replacement strategies where soybean meal has received ample attention. Most studies evaluating these strategies have been carried out under laboratory conditions which greatly differ from production conditions in ponds. This study evaluated a fish meal replacement strategy using vegetable protein sources in practical feeds for marine shrimp reared in ponds. Juvenile Pacific white shrimp ( Litopenaeus vannamei) (0.03 g) were stocked into 16 0.1-ha low-water exchange ponds and reared over an 18-week period. Four commercially extruded diets formulated to contain 35% crude protein and 8% lipids were evaluated. These diets included varying levels of fish meal (9, 6, 3, and 0%) which was replaced by a combination of increasing levels of soybean meal (32.5, 34.9, 37.2 and 39.6% respectively) and corn gluten meal (0.0, 1.7, 3.2, and 4.8% respectively) to replace the protein originating from fish meal. At the conclusion of the experimental period, there were no significant differences ( P ≥ 0.05) in shrimp production among the test diets. Mean final yield, final weight, feed conversion ratio and survival values ranged from 5363–6548 kg ha − 1 , 18.4–20.7 g, 1.38–1.12 and 84.0–94.0%, respectively. Although not significant, as higher levels of plant protein sources were included in the diets, the economic analysis showed a general increase in the partial gross returns of shrimp production. Results from this study demonstrate that fish meal can be completely replaced using alternative vegetable protein sources in practical shrimp feeds without compromising production and economic performance of L. vannamei reared in ponds.

In Vitro Evidence of Laminarinase Activity in the Digestive Gland of Juvenile Pacific White Shrimp Litopenaeus vannamei

Journal of the World Aquaculture SocietyVolume 35, Issue 4 p. 546-550 Free to Read In Vitro Evidence of Laminarinase Activity in the Digestive Gland of Juvenile Pacific White Shrimp Litopenaeus vannamei S. Divakaran, S. Divakaran The Oceanic Institute, Makapuu Point, Waimanalo, Hawaii 96795 USASearch for more papers by this authorShaun M. Moss, Shaun M. Moss The Oceanic Institute, Makapuu Point, Waimanalo, Hawaii 96795 USASearch for more papers by this author S. Divakaran, S. Divakaran The Oceanic Institute, Makapuu Point, Waimanalo, Hawaii 96795 USASearch for more papers by this authorShaun M. Moss, Shaun M. Moss The Oceanic Institute, Makapuu Point, Waimanalo, Hawaii 96795 USASearch for more papers by this author First published: 03 April 2007 https://doi.org/10.1111/j.1749-7345.2004.tb00123.xCitations: 9AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume35, Issue4December 2004Pages 546-550 RelatedInformation

Biological Characterization of a Less Virulent Taura Syndrome in Pacific White Shrimp Litopenaeus vannamei (Crustacea: Decapoda): Gross Signs, Histopathological Lesions, and Mortalities

Taura syndrome (TS) was first recognized in shrimp farms located near the mouth of the Taura River in the Gulf of Guayaquil, Ecuador in mid1992 (JimCnez 1992; Lightner et al. 1995), where the disease caused catastrophic losses with cumulative mortality rates from 60% to >90% of affected pond-cultured, juvenile Pacific white shrimp Litopenaeus vannamei (Perez Farfante and Kensley 1997). The geographic distribution of the disease now includes Ecuador, the adjacent region of Peru, the Pacific and Caribbean coast of Colombia, Honduras, Guatemala, El Salvador, northeast Brazil, Nicaragua, Belize, the states of Hawaii, Florida, and Texas in the USA, the Mexican states of Sonora, Sinaloa, Chiapas, and Guerrero, and recently Taiwan (Lightner 1996; Chien et al. 1999). The epizootiological and laboratory studies that followed its discovery and spread from Ecuador showed that Taura syndrome (TS) had a viral etiology in the American (L. vannamei, L. stylirostris, L. schmitti, L. setiferus, Farfuntepenaeus aztecus) and Asian (Penaeus monodon, Marsupenaeus japonicus, Fenneropenaeus chinensis) penaeid species naturally or experimentally infected by the virus. Litopenaeus vannamei was by far the most severely affected (Brock et al. 1995, 1997; Hasson et al. 1995, 1999b; Lightner 1996; Overstreet et al. 1997). Infectivity studies demonstrated that TS could be induced in specific-pathogen-free (SPF) L. vannamei. Shrimp started dying after being fed TSV-infected tissue between day 4 or 5, with mortalities of 80% (Brock et al. 1995). Test animals were also infected by intramuscular injection with crude homogenate and cell-free suspensions, from TSV-infected Ecuatorian L. vannamei, causing mortalities of 73% to 87% among treated groups. All moribund shrimp demonstrated moderate to severe pathognomonic TS lesions (Hasson et al. 1995), which consist of pyknotic and karyorrhectic nuclei and generally spherical cytoplasmic inclusions with multifocal areas of necrosis of the cuticular epithelium giving TS lesions a peppered or buckshot-riddled appearance (Brock et al. 1995; Lightner et al. 1995; Hasson et al. 1995; Lightner 1999). The hemispheric geographic distribution of TS indicates that the same virus or a closely related one is responsible for the TS epizootics that have occurred throughout America since 1992 (Hasson et al. 1999a). Ecuatorian and Hawaiian TS virus isolates were found to be identical in their biophysical, biochemical, and biological characteristics, and they were considered to be the same virus (Bonami et al. 1997). In early 1995, TSV was detected in wild adult L. vannamei collected from the offshore fishery of the southern Mexican state of Chiapas, near its border with Guatemala and near where TS had first appeared in

Effect of Various Dietary Lipid Levels on Quantitative Essential Fatty Acid Requirements of Juvenile Pacific White Shrimp Litopenaeus vannamei

AbstractA 6‐wk feeding trial was conducted to evaluate the effect of various dietary lipid levels on quantitative requirements for essential fatty acids (EFA) by juvenile Pacific white shrimp Litopenaeus vannamei. A factorial experiment with three dietary lipid levels (3, 6, and 9%) and three dietary levels (0.5, 1, and 2%) of a mixture of n‐3 highly unsaturated fatty acids (HUFA) was used. An increase in quantitative requirements for EFA with increasing supplementation level of dietary lipid was not demonstrated. Results suggested that this shrimp species appeared to be able to satisfy its n‐3 HUFA requirements when they were supplied at 0.5% of diet; this dietary level may be even lowered. Moreover, depressed growth was observed in shrimp fed diets with the HUFA mixture supplemented at 2%. In addition, the present study showed that increasing the dietary lipid level had an effect on lipid composition of shrimp, by increasing lipid deposition in hepatopancreas and muscle tissue, but without a significant effect on growth.

A Profound Effect of Hyperthermia on Survival of Litopenaeus vannamei Juveniles Infected with White Spot Syndrome Virus

AbstractThis study was conducted to examine the effect of increasing seawater temperature on White Spot Syndrome Virus (WSSV) infection in juvenile Pacific White shrimp (Litopenaeus vannamei). Infection by WSSV was achieved using two methods, intramuscular injection and per os (oral) administration. Forty injected and 20 per os infected animals were kept in heated tanks at 32.3 ± 0.8 C, and the same number of WSSV infected animals were maintained in tanks at ambient temperature (25.8 ± 0.7 C). Despite the route of exposure, there were no survivors among the animals kept at ambient temperature; whereas, in heated tanks the survival of the WSSV infected juvenile shrimp was always above 80%, suggesting the existence of a beneficial effect from hyperthermia that mitigated the progression of WSSV disease. Moreover, this beneficial effect was not attributable to viral inactivation. Infected animals kept at 32 C had histologically detectable lymphoid organ spheroids suggestive of a chronic viral infection but were PCR negative (hemolymph) for WSSV. These findings might be related to low viral replication in WSSV‐infected shrimp held at the higher environmental temperature. When the WSSV‐infected shrimp were transferred from 32 C to ambient temperature, the mortality from WSSV ensued and was always 100%. Although the mechanism related to the beneficial effect of heating was not determined, our results indicate that increasing the water temperature modifies dramatically the natural history of the WSSV disease and the survival curves of WSSV‐infected juvenile Pacific White shrimp.