Litopenaeus Vannamei Research Articles

A comparative study on the taste quality of whiteleg shrimp (Penaeus vannamei) under two different transportation strategies

The current study comprehensively investigated the impacts of simulated water-based transportation and waterless transportation on the taste attributes and nonvolatile taste components in shrimp muscle. The results of the electronic tongue revealed that the umami sensation increased while the sweetness decreased after transportation. The primary taste components of shrimp muscle from the various transportation groups were identified using two-dimensional correlation spectroscopy, including free amino acids, nucleotides, and organic acids. The highest equivalent umami concentration was observed in the waterless transportation group (18.78 g MSG/100 g), followed by the water-based transportation (15.33 g MSG/100 g) and fresh groups (12.08 g MSG/100 g). The contents of main taste-active compounds, especially umami amino acids, organic acids, Na+, Cl−, and 5′-nucleotides, were higher in the shrimp muscle of the waterless transportation group, which were more likely to be accepted and preferred. This research provided insights into improving shrimp muscle taste quality through the appropriate application of transportation strategies.

Gene structure, expression and function analysis of the MyoD gene in the Pacific white shrimp Litopenaeus vannamei

The Pacific white shrimp Litopenaeus vannamei is a representative species of decapod crustacean and an economically important marine aquaculture species worldwide. However, research on the genes involved in muscle growth and development in shrimp is still lacking. MyoD is recognized as a crucial regulator of myogenesis and plays an essential role in muscle growth and differentiation in various animals. Nonetheless, little information is available concerning the function of this gene among crustaceans. In this study, we identified a sequence of the MyoD gene (LvMyoD) with a conserved bHLH domain in the L. vannamei genome. Phylogenetic analysis revealed that both the overall protein sequence and specific functional sites of LvMyoD are highly conserved with those of other crustacean species and that they are evolutionarily closely related to vertebrate MyoD and Myf5. LvMyoD expression is initially high during early muscle development in shrimp and gradually decreases after 40 days post-larval development. In adults, the muscle-specific expression of LvMyoD was confirmed through RT–qPCR analysis. Knockdown of LvMyoD inhibited the growth of the shrimp in body length and weight. Histological observation and transcriptome sequencing of muscle samples after RNA interference (RNAi) revealed nuclear agglutination and looseness in muscle fibers. Additionally, we observed significant effects on the expression of genes involved in heat shock proteins, myosins, actins, protein synthesis, and glucose metabolism. These findings suggest that LvMyoD plays a critical role in regulating muscle protein synthesis and muscle cell differentiation. Overall, this study highlights the involvement of LvMyoD in myogenesis and muscle growth, suggesting that it is a potentially important regulatory target for shrimp breeding efforts.

Astaxanthin supplementation enhances low-temperature stress tolerance, immune-related genes, and resistance to Vibrio parahaemolyticus in Whiteleg Shrimp Penaeus vannamei

Astaxanthin supplementation enhances low-temperature stress tolerance, immune-related genes, and resistance to Vibrio parahaemolyticus in Whiteleg Shrimp Penaeus vannamei

Comparative Transcriptomic Analysis of WSSV-Challenged Penaeus vannamei with Variable Resistance Levels.

The Pacific white shrimp, Penaeus vannamei, is highly susceptible to white spot syndrome virus (WSSV). Our study explored the transcriptomic responses of P. vannamei from resistant and susceptible families, uncovering distinct expression patterns after WSSV infection. The analysis revealed a higher number of differentially expressed genes (DEGs) in the susceptible family following WSSV infection compared to the resistant family, when both were evaluated against their respective control groups, indicating that the host resistance of the family line influences the transcriptome. The results also showed that subsequent to an identical duration following WSSV infection, there were more DEGs in P. vannamei with a high viral load than in those with a low viral load. To identify common transcriptomic responses, we profiled DEGs across families at 96 and 228 h post-infection (hpi). The analysis yielded 64 up-regulated and 37 down-regulated DEGs at 96 hpi, with 33 up-regulated and 34 down-regulated DEGs at 228 hpi, showcasing the dynamics of the transcriptomic response over time. Real-time RT-PCR assays confirmed significant DEG expression changes post-infection. Our results offer new insights into shrimp's molecular defense mechanisms against WSSV.

Metabolism effects of static magnetic field‐assisted freezing on shrimp (Penaeus vannamei)

SummaryShrimp undergo rapid deterioration after death, primarily due to enzyme activity and microbial growth, with freezing serving as its primary preservation method. In this study, shrimp underwent both conventional freezing (CF) and magnetic field‐assisted freezing (MF), and the shrimp meat's metabolites were scrutinised via metabonomic analysis techniques. The results demonstrate that MF treatment effectively preserved umami components like glutamic acid (log2(FC) = 0.37) and inosinic acid (1.02) while inhibiting the accumulation of spoilage‐related metabolites such as inosine (HxR) (−2.51), hypoxanthine (Hx) (−1.43) and uric acid (UA) (−1.24). Moreover, specific compounds, including 3‐methylhistidine, 1,6‐bisphosphate, phosphatidylcholine (PC), phosphatidylethanolamine (PE), HxR, Hx and UA were recognised as potential biomarkers throughout the freezing process. This research offers crucial insights into the intricate molecular mechanisms behind magnetic field‐assisted freezing.

Evaluation of combined disinfection methods of infectious myonecrosis virus (IMNV) in seawater using Pacific white shrimp (Penaeus vannamei)

The global spread of infectious myonecrosis virus (IMNV) poses a serious threat to the shrimp aquaculture industry and urgent actions are needed to control its transmission and prevalence. Aquaculture water serves as an important route of IMN transmission, and disinfection of aquaculture water is crucial to ensure the health and stable production of shrimp. In this study, we introduced the purified IMNV into seawater and then subjected the seawater to different disinfection treatments (PMS, PMS + PVP-I and ClO2 + PVP-I) before culturing shrimp. By performing RT-qPCR tests on both the seawater and Pacific white shrimp (Penaeus vannamei) samples, we evaluated the effectiveness of the different disinfection methods in eradicating IMNV from the seawater. The results showed that peroxymonosulfate (PMS) could effectively reduce the viral load of IMNV in seawater samples. The combined disinfection approach (10 ppm (ppm)) of PMS disinfection (combined with povidone‑iodine) followed by a standing time of at least 2 days, or 10 ppm chlorine dioxide disinfection (combined with povidone‑iodine) followed by a standing time of at least 4 days, were found to be successful in the efficient disinfection of IMNV. This research provides a method to effectively remove IMNV from marine aquaculture water, thereby contributing to reducing the risk of IMN disease transmission and providing a sound basis for the sustainable and healthy development of the shrimp aquaculture industry.

Exploiting hybrid vigor to enhance survival and growth for whiteleg shrimp (Litopenaeus vannamei): A complete diallel cross experiment

Whiteleg shrimp (Litopenaeus vannamei) is an economically important cultured species that is extensively cultured in China. However, there is the potential for further optimization of its survival and growth traits that are key determinants of productivity in aquaculture. This study investigated the efficacy of hybridization, a genetic improvement technology leveraging hybrid vigor, as a strategy for enhancing these traits in L. vannamei. The study was conducted using a 4 × 4 complete diallel cross experiment involving four selected strains (5, 8, 9, and 10), with the aim of identifying potential crosses exhibiting hybrid vigor. The most suitable crosses were those between strains 8 and 9, where the mid-parent heterosis (H89) was 16.52% for survival and 18.93% for growth. Our findings revealed that most reciprocal hybrids displayed higher rates of survival than their inbred parents. Additionally, an age-dependent increase in the heterosis effect on weight was observed over mid-parents and single-parents in most hybrid offspring. These findings suggest that hybridization could be a promising approach to improving the survival and growth of whiteleg shrimp. Our crossing experiment has yielded novel genetic resources for shrimp breeding, ultimately enhancing the economic importance of whiteleg shrimp.

Synbiotic encapsulation against Vibrio parahaemolyticus infection in whiteleg shrimps

Vibrio parahaemolyticus is a severe pathogenic bacterium which causes significant mortality and economical loss in shrimp farming. To control vibriosis in whiteleg shrimps (Litopenaeus vannamei), we developed synbiotic beads by microencapsulating probiotic of Lactobacillus plantarum and prebiotic of xanthan gum in agarose matrix through emulsion technique. Coculture method indicated that synbiotic beads reduce viability of Vibrio parahaemolyticus by 3 orders of magnitude. The high inhibitory activity of synbiotic beads against pathogen could result from the antibacterial substances secreted from encapsulated probiotics, and access blocking of pathogens to prebiotics as food source so that the encapsulated prebiotics solely stimulate nearby probiotic growth without boosting pathogen growth. Bacterial challenge test indicated that exposure to synbiotic beads in advance can delay mortality and increase shrimp survival from 10% to 57%. As a smart encapsulation platform, our design can be extended to various probiotics, prebiotics, and pathogens, thus providing an alternative strategy to the use of antibiotics for disease prevention and sustainable aquaculture.

Assessment of fish protein hydrolysate as a substitute for fish meal in white shrimp diets: Impact on growth, immune response, and resistance against Vibrio parahaemolyticus infection

This study investigated the effects of fish protein hydrolysate derived from barramundi on growth performance, muscle composition, immune response, disease resistance, histology and gene expression in white shrimp (Penaeus vannamei). In vitro studies demonstrated FPH enhanced mRNA expressions of key immune-related genes and stimulated reactive oxygen species (ROS) production and phagocytic activity in shrimp hemocytes. To evaluate the effects of substituting fish meal with FPH in vivo, four isoproteic (43%), isolipidic (6%), and isoenergetic diets (489 kcal/100g) were formulated with fish meal substitution levels of 0% (control), 30% (FPH30), 65% (FPH65), and 100% (FPH100). After 8-week feeding, the growth performance of FPH65 and FPH100 were significantly lower than that of control and FPH30 (p < 0.05). Similarly, the midgut histological examination revealed the wall thickness and villi height of FPH100 were significantly lower than those of control (p < 0.05). The shrimps were received the challenge of AHPND+ Vibrio parahaemolyticus at week 4 and 8. All FPH-fed groups significantly enhanced resistance against Vibrio parahaemolyticus at week 4 (p < 0.05). However, this protective effect diminished after long-period feeding. No significant difference of survival rate was observed among all groups at week 8 (p > 0.05). The expressions of immune-related genes were analyzed at week 4 before and after challenge. In control group, V. parahaemolyticus significantly elevated SOD in hepatopancreas and Muc 19, trypsin, Midline-fas, and GPx in foregut (p < 0.05). Moreover, hepatopancreatic SOD of FPH65 and FPH100 were significantly higher than that of control before challenge (p < 0.05). Immune parameters were measured at week 8. Compared with control, the phagocytic index of FPH 30 was significantly higher (p < 0.05). However, dietary FPH did not alter ROS production, phenoloxidase activity, phagocytic rate, and total hemocyte count (p > 0.05). These findings suggest that FPH30 holds promise as a feed without adverse impacts on growth performance while enhancing the immunological response of white shrimp.

Reusing biofloc-culture water and microbubble aeration for culturing the white-leg shrimp Litopenaeus vannamei

This study investigated the effects of reusing biofloc-culture water for culturing the white-leg shrimp Litopenaeus vannamei. Experiments were conducted for two continuous cycles without water exchange for 30 days during the nursery stage. The studies were performed with two different aeration systems, namely microbubbles (MB) and large air bubbles (LB). Water quality parameters such as dissolved oxygen (DO), temperature, pH, salinity, alkalinity, total ammonia nitrogen (TAN), nitrite, nitrate, settleable solids (SS), and total suspended solids (TSS) were recorded throughout the culture days. Also, comparisons were performed on parameters of the shrimp growth, i.e., body weight and length, feed conversion ratio (FCR), and specific growth rates (SGR) for the 30-day culture for Cycles 1 and 2. Cycle 2 showed no deterioration in water quality and no significant difference in growth performance compared to Cycle 1 for either aeration method (MB and LB). However, when comparing between aeration methods, MB aeration significantly improved the DO of the water and accelerated the conversion of TAN to nitrate. Shrimps in the MB aeration system were significantly larger (by 39%) with a lower FCR value (reduced by 30%) than in the LB aeration system. Harmful bacteria from the Vibro group were detected. However, they occurred at a minimum level in both cycles and aeration types. Overall, the biofloc-culture water might be reused for the subsequent cycle, while the MB aeration might promote the growth of biofloc and L. vannamei.

IMPLEMENTATION OF COLD CHAIN SYSTEM IN PEELED DEVEINED TAIL-ON VANNAMEI SHRIMP (Litopenaeus vannamei) PRODUCTS

Vannamei (Litopenaeus vannamei) Peeled Deveined Tail-On (PDTO) shrimp is frozen shrimp product consumers highly preferred. However, shrimp products are easily perishable that require a proper cold chain system to preserve their quality, shelf life, and nutritional value. This study investigated the cold chain implementation of PDTO shrimp processing in the fishery industry. The temperature of shrimp products, water, and rooms was monitored during processing. Results showed that the shrimp temperature measured in each process was below 5°C. However, abusive temperatures were detected in water used in the peeling and deveining step and soaking process, while water and shrimp temperatures altered each other. Moreover, room temperatures were recorded under 20°C, conforming to Ministry of Marine and Fisheries regulations. Air Blast Freezer and cold storage temperatures revealed that ABF and CS could not meet the company’s temperature standards. These findings may help shrimp companies monitor steps indicating to have temperature abuse attentively.

Genome-wide QTL and eQTL mapping reveal genes associated with growth rate trait of the Pacific white shrimp (Litopenaeus vannamei)

BackgroundGrowth rate is a crucial economic trait for farmed animals, but the genetic regulation of this trait is largely unknown in non-model organisms such as shrimp.ResultsIn this study, we performed genome-wide phenotypic quantitative trait loci (QTL) and expression quantitative trait loci (eQTL) mapping analyses to identify genes affecting the growth rate of Pacific white shrimp (Litopenaeus vannamei), which is the most commercially-farmed crustacean worldwide. We used RNA-sequencing of 268 individuals in a mapping population, and subsequently validated our findings through gene silencing and shrimp growth experiments. We constructed a high-density genetic linkage map comprising 5533 markers spanning 44 linkage groups, with a total distance of 6205.75 cM and an average marker interval of 1.12 cM. Our analyses identified 11 QTLs significantly correlated with growth rate, and 117,525 eQTLs. By integrating QTL and eQTL data, we identified a gene (metalloreductase STEAP4) highly associated with shrimp growth rate. RNA interference (RNAi) analysis and growth experiments confirmed that STEAP4 was significantly correlated with growth rate in L. vannamei.ConclusionsOur results indicate that the comprehensive analysis of QTL and eQTL can effectively identify genes involved in complex animal traits. This is important for marker-assisted selection (MAS) of animals. Our work contributes to the development of shrimp breeding and available genetic resources.

Cumulative mortalities in white leg shrimp, Litopenaeus vannamei Boone 1931, cultured in biofloc system in Egypt reflected new record of Fusarium verticillioides infection

AbstractThe Egyptian aquaculture sector is still struggling to establish L. vannamei culture. In an effort to stimulate shrimp production with minimal environmental impact and less water loss, biofloc technology (BFT) has been employed. Chronic mortality was recently observed in L. vannamei which was raised in the BFT system. Examining samples of moribund shrimp revealed sporadic melanization on the musculature and gills, suggesting the potential existence of black gill disease. The present work was carried out to isolate and identify potentially implicated fungus species based on mycological properties of interest. To isolate and serve as initial identification tools, wet mount preparations and colonial features, along with slide culture techniques, were used. PCR assays, gene sequencing, and phylogenetic analyses were used in the molecular identification process to clarify the confirmation of the fungal isolates that were acquired. The pathogenicity tests were designed to fulfil Koch’s postulates in addition to clarifying the infectivity of isolated fungus. Moreover, histopathological examination was employed to notice tissues’ alterations associated with experimentally infected shrimp. The results revealed the isolation of three fungal isolates, namely, BNS 1117, BNS 2117, and BNS 3117, that were confirmatively identified as Fusarium verticillioides, and their selected sequences were submitted to Genbank. Moreover, experimental infection using F. verticillioides selected isolate (BNS 31,117) at both high (5 × 105 CFU/mL, group A) and low (3 × 105 CFU/mL, group B) doses of its conidial suspensions experienced cumulative mortality of 72.2% and 21.1%, respectively. Besides, the selected isolate was re-isolated from the experimentally infected shrimp in a pure form, which satisfied Koch’s postulates. Histopathological alterations demonstrated several degrees of either degenerative, oedema, or proliferative changes in the hepatopancreas, musculatures, and gills, respectively. This study sets a new record for F. verticillioides to be included in Fusarium species linked to shrimp mortality.

Dietary Lysophosphatidylcholine Improves the Uptake of Astaxanthin and Modulates Cholesterol Transport in Pacific White Shrimp Litopenaeus vannamei

Astaxanthin (AST), functioning as an efficient antioxidant and pigment, is one of the most expensive additives in shrimp feeds. How to improve the uptake efficiency of dietary astaxanthin into farmed shrimp is of significance. The present study investigated the effects of lysophosphatidylcholine (LPC), an emulsifier, on dietary astaxanthin efficiency, growth performance, body color, body composition, as well as lipid metabolism of juvenile Pacific white shrimp (average initial body weight: 2.4 g). Three diets were prepared: control group, the AST group (supplemented with 0.02% AST), and the AST + LPC group (supplemented with 0.02% AST and 0.1% LPC). Each diet was fed to triplicate tanks, and each tank was stocked with 30 shrimp. The shrimp were fed four times daily for eight weeks. The AST supplementation improved the growth of white shrimp, while LPC further promoted the final weight of shrimp, but the whole-shrimp proximate composition and fatty acid composition were only slightly affected by AST and LPC. The LPC supplementation significantly increased the astaxanthin deposition in the muscle. The LPC supplementation significantly increased the shell yellowness of both raw and cooked shrimp compared to the AST group. Moreover, the dietary LPC increased the high-density lipoprotein-cholesterol content but decreased the low-density lipoprotein-cholesterol content in the serum, indicating the possible regulation of lipid and cholesterol transport. The addition of astaxanthin significantly up-regulated the expression of npc2 in the hepatopancreas compared to the control group, while the addition of LPC down-regulated the expression of mttp compared to the AST group. In conclusion, the LPC supplementation could facilitate the deposition of dietary astaxanthin into farmed shrimp and further enlarge the beneficial effects of dietary astaxanthin. LPC may also independently regulate shrimp body color and cholesterol transportation. This was the first investigation of the promoting effects of LPC on dietary astaxanthin efficiency.

Dietary Poly-β-Hydroxybutyrate Improved the Growth, Non-specific Immunity, Digestive Enzyme Activity, Intestinal Morphology, Phagocytic Activity, and Disease Resistance Against Vibrio parahaemolyticus of Pacific White Shrimp, Penaeus vannamei.

This study assessed the effects of dietary supplementation of poly-β-hydroxybutyrate (PHB) on growth performance, feed efficiency, non-specific immunity, digestive enzyme capacity, phagocytic activity, hemocyte count, intestinal morphology, and disease resistance against Vibrio parahaemolyticus of Pacific white shrimp (Penaeus vannamei). Six diets were prepared by supplementing graded levels of PHB at 0.00, 0.25, 0.50, 1.00, 2.00, and 4.00% (Con, P0.25, P0.5, P1.0, P2.0, and P4.0, respectively). Triplicate groups of 90 shrimps (initial body weight 0.25 ± 0.01g) per treatment were randomly assigned and fed an experimental diet for 56days. The growth performance of shrimp was significantly improved by 1% dietary PHB supplementation. PHB-included diets fed shrimp showed significantly improved hepatopancreatic trypsin, chymotrypsin, and pepsin activities. Villus height was significantly increased with dietary PHB supplementation, and villus width was increased at a 1% inclusion level. P0.25, P0.5, and P4.0 groups significantly increased phenoloxidase activity, and the P2.0 group significantly increased anti-protease activity compared to the Con group. The survival of shrimp challenged against V. parahaemolyticus was higher in P0.5, P1.0, and P2.0 groups than in the Con diet. Dietary PHB supplementation improved weight gain, digestive enzyme activity, intestinal morphology, non-specific immunity, and disease resistance against V. parahaemolyticus of shrimp. According to the above observations, the optimal dietary PHB supplementation level for maximum weight gain would be 1% for Pacific white shrimp.

Komparasi Metode Isolasi DNA dalam Mendeteksi Gen toxR Bakteri Vibrio parahaemolyticus pada Udang Vaname (Litopenaeus vannamei)

Vibrio parahaemolyticus bacteria is one of the dangerous pathogens in vaname shrimp farming (Litopenaeus vannamei). Infection with this bacterium can cause mass mortality in shrimp and considerable losses for farmers. This bacterium also has a specific gene, the toxR gene, which is used to detect its presence. The successful detection of this bacterium determines the success of handling the disease it causes. The purpose of the study was to determine the optimal DNA isolation method in detecting the toxR gene of Vibrio parahaemolyticus bacteria in vaname shrimp. The research was conducted by means of molecular biology-based identification using two DNA isolation protocols, namely Chloroform and Boilling lysis buffer. Visualization results showed that toxR gene DNA appeared in samples isolated with Boiling Lysis Buffer in Tryptic Soy Broth (TSB) media culture preparation. This means that the boiling lysis buffer method is a suitable DNA isolation method for detecting the toxR gene of the Vibrio parahaemolyticus bacteria in white shrimp.

Correction: Evaluation of a single-cell protein as a dietary fish meal substitute for whiteleg shrimp Litopenaeus vannamei

Correction: Evaluation of a single-cell protein as a dietary fish meal substitute for whiteleg shrimp Litopenaeus vannamei

Molecular authentication and discrimination between banana shrimp and Pacific white shrimp by duplex PCR-lateral flow dipstick (dPCR-LFD) system

Banana shrimp is easily substituted by Pacific white shrimp due to its relatively similar morphology and appearance. The duplex PCR-lateral flow dipstick (dPCR-LFD) system was developed to authenticate these two species based on the mitochondrial cytochrome b (Cytb) gene. Two pairs of species-specific primers were designed for dPCR amplification. The specificity was also tested toward nine marine species. The sensitivity of the method was also evaluated at the DNA range of 0.02 %-60 % of adulterated Pacific white shrimp DNA in DNA from banana shrimp. Several types of cooked samples under various conditions were also tested. The developed dPCR-LFD system could specifically differentiate banana shrimp from Pacific white shrimp. No cross-amplification was observed in the specificity test. The sensitivity test showed the detection limit of 0.02 % (0.01 ng) of Pacific white shrimp DNA. The cooking processes including boiling, frying, and steaming did not show any effect on the efficiency of the dPCR-LFD system. This technique could be therefore implemented for the authentication of banana shrimp and Pacific white shrimp products as well as further use for other seafood frauds.

Effect of dietary krill oil levels on the regulation of ovary development in Pacific white shrimp (Litopenaeus vannamei) broodstock

Krill oil is rich in phospholipids and has been proven to significantly promote ovarian development in shrimp. However, the optimal level and related mechanism are unknown. In this study, four isonitrogenous and isolipidic diets were prepared. These diets included different gradients of krill oil supplementation (3%, 6%, and 9%), with no-krill oil serving as a control. Female Litopenaeus vannamei broodstock with stage I ovarian development were fed these diets for 28 days. The results showed that the inclusion of krill oil in the diet had a positive effect on ovarian development in female shrimp, particularly at the 6% supplementation level. This was evident from the significant improvements in the gonadosomatic index and in the 17β-estradiol, progesterone, and methyl farnesoid levels. Moreover, 6% krill oil supplementation facilitated lipid accumulation in the hepatopancreas, promoted the deposition of yolk granules within the oocyte, and significantly enhanced the mobilization efficiency of triglycerides and total cholesterol from the hepatopancreas to the ovary. The upregulation of the serum metabolites choline and phosphorylcholine promotes the synthesis of phosphatidylcholine and triglycerides. Additionally, prostaglandin E2 stimulates the production of ovarian steroid hormones. Acamprosate influences the activity of glutamic acid, potentially leading to a reduction in the secretion of gonadal inhibitory hormones. Multiomics analysis revealed joint enrichment of differentially altered metabolites and differentially expressed genes in pathways involved in arachidonic acid metabolism, cholesterol metabolism, and ovarian steroid synthesis. Additionally, there was significant enrichment in glycerophospholipid metabolism. The expression of the cytosolic phospholipase A2 gene was upregulated in both the lipid metabolism and steroid synthesis pathways. Moreover, the mRNA expression levels of 3β-hydroxysteroid dehydrogenase/delta 5- > 4-isomeras, cytochrome P450 2 L1, and prostaglandin H synthase 2 were also upregulated in the ovarian steroid synthesis pathway. In conclusion, supplementing the diet with 6% krill oil is optimal for promoting lipid metabolism and steroid hormone secretion in female L. vannamei broodstock, thereby enhancing ovarian development and maturation.

Effect of Calanus finmarchicus Hydrolysate Inclusion on Diet Attractiveness for Whiteleg Shrimp (Litopenaeus vannamei)

Shrimp feed formulations have moved towards less fish meal and more of the readily available and cheaper plant proteins. To counteract the lower attractiveness and palatability of plant proteins, feeds are supplemented with ingredients known to have chemoattractive properties that will increase feed intake. This study investigated the putative chemoattractive effect of Calanus finmarchicus hydrolysate, when used as a dietary supplement in shrimp feeds. C. finmarchicus is a zooplankton species native to the northern Atlantic Ocean and is a novel and sustainable raw material for shrimp feed products. Diet attractiveness was evaluated in a 24-day feeding trial with whiteleg shrimp (Litopenaeus vannamei) by measuring the intake of 12 diets with various levels of fish meal, calanus hydrolysate, and krill (Euphausia superba) meal. Higher inclusion rates of both ingredients resulted in increased feed intakes, and supplementing the high fish meal diet with calanus hydrolysate gave a statistically significant higher feed intake. Low molecular weight peptides, chemoattractive amino acids, and the water-soluble nature of the hydrolysate could explain the chemoattractive properties observed in the study.