Krill Meal Research Articles

Acoustic feeding responses using marine chemoattractants in plant-based diets for naive and non-naive Litopenaeus vannamei

The inclusion of chemoattractants has been investigated to improve the attractability and palatability of plant-based shrimp diets. A more recent approach utilizes passive acoustic monitoring (PAM) to record the sounds (clicks) emitted by shrimp during feeding activity allowing the identification of behavioral responses related to the diets. In the present study we automatically identified click signals in PAM recordings at sampling frequency of 192 kHz. This methodology was applied to evaluate the efficiency of three chemoattractants (krill meal, squid meal and fish hydrolysate) added to a basal all-plant diet on the acoustic feeding behavior and food consumption of naive (without acclimation) and non-naive (acclimated to the diets) Litopenaeus vannamei. Five diets were used: basal all-plant diet (AP, negative control) and its modifications to contain 20 g/Kg of krill meal (AP+KM), 20 g/Kg of squid meal (AP+SM) and 40 g/Kg of fish hydrolysate (AP+FH); a diet with 120 g/Kg fishmeal (FM) was used as a positive control. Ten shrimp (6.8 ± 0.6 g; mean ± SD) were stocked per aquarium (70 L) in a clear water recirculation system (30 aquaria, five diets with six replicates). The food consumption and acoustic activity were evaluated simultaneously in each aquarium over a 30-min period during two consecutive days for each trial, naive and non-naive shrimp. Strong positive relationships (r = 0.78–0.81; P < 0.001) were found between food consumption and total number of clicks emitted by naive and non-naive shrimp. Overall, the inclusion of the chemoattractants to the plant-based diet had a positive effect improving acoustic feeding behavior and food consumption for naive and non-naive L. vannamei. In particular, the response of non-naive shrimp to chemoattractants was markedly increased, and the highest clicking activity was attained by using krill meal (AP+KM), followed by fish hydrolysate (AP+FH). The new analytical method proved to be a useful alternative approach for studying shrimp feeding behavior, also indicating the potential of PAM to forecast feed intake and improve efficiency of feed management.

Utilising feed effectors and automated feeders for semi‐intensive pacific white shrimp (Litopenaeus vannamei) production

AbstractFeed effectors have been suggested to improve the efficiency of plant‐based shrimp diets by increasing attractability and palatability. This research trial aimed to expand upon previous Pacific white shrimp (Litopenaeus vannamei) research involving plant‐based diets, feed effectors and passive acoustic monitoring (PAM) in a laboratory setting by conducting a feed trial in outdoor semi‐intensive ponds stocked at 30 shrimp/m2. A 13‐week trial was conducted in sixteen 0.1‐ha ponds equipped with PAM‐integrated feeders, which allowed for demand‐style feeding. Four soy‐optimised diets, consisting of an ‘all‐plant’ basal diet (AP) and three diets with an attractant (2% krill meal (KM), 2% squid meal (SM), 4% fish hydrolysate (FH)), were fed to the shrimp for a period of 74–75 days. Significantly more (p = 0.0131) of the FH diet was fed to the respective ponds than the KM and AP diets, suggesting that the addition of FH to soy‐optimised diets increases the intensity of the feed response in shrimp cultured in semi‐intensive ponds. The same diets offered in predetermined amounts to shrimp in an outdoor, recirculating green water system resulted in no significant differences (p &gt; 0.05) between treatment means for final weight or weekly growth rate. However, there was a significant difference (p = 0.021) in survival between the AP treatment (85.83%) and the FH treatment (95.83%), which led to the final biomass (p = 0.004) and FCR (p &lt; 0.0001) of the AP treatment being significantly different from all other treatments. The reduced response observed in the AP treatment suggests that the addition of attractants may improve the performance of plant‐based diets in RAS.

Influences of replacing dietary fish meal by Antarctic krill meal on growth performance, immunity and muscle quality of white shrimp Litopenaeus vannamei

The present study was conducted to investigate the effects of Antarctic krill Euphausia superba meal replacing dietary fish meal on the growth performance, immunity and muscle quality of white shrimp Litopenaeus vannamei (initial body weight: 4.080 ± 0.143 g, mean±SD). The replacement levels were designed as 0%, 5%, 15%, 30%, 45%, 60%, 75% and 100%, respectively. After a 52-day feeding trial, results showed that the specific growth rate (P = 0.129) and feed intake (P = 0.217) of shrimp were not significantly affected. Feed conversion ratio (FCR, P = 0.000), protein efficiency ratio (PER, P = 0.000) and protein retention (PR, P = 0.000) were significantly affected with a quadratic positive trend for FCR, a linear and quadratic negative trend for PER and a quadratic negative trend for PR. The total haemocyte count (P = 0.307), respiratory burst (P = 0.168), activities of superoxide dismutase (P = 0.221) and glutathione reductase (P = 0.170) in serum were not significantly affected. While, malondialdehyde content (P = 0.000), acid phosphatase (P = 0.000) and alkaline phosphatase activity (P = 0.000) in serum were significantly decreased both in linear and quadratic trend. The carotenoid content in exoskeleton (P = 0.019) and pH in muscle (P = 0.000) were linearly increased. With the increasing replacement levels, n-3 PUFA content (P = 0.001) in muscle significantly decreased and n-6 PUFA (P = 0.000) increased. The ratio of essential amino acid to total amino acid (P = 0.000) and the inosinic acid content in muscle (P = 0.002) were significantly increased with the dietary replacement levels in a linear trend. In conclusion, Antarctic krill meal can totally replace dietary fish meal without negative impact on the growth of L. vannamei. From the perspective of feed utilization, after the quadratic regression analysis of FCR, PER and PR, the appropriate replacement level of dietary fish meal by krill meal for L. vannamei was 52.78%, 68.50% and 47.41%, respectively (i.e., dietary krill meal level was 13.27%, 17.22%, and 11.92%, respectively).

Application of stable isotope analysis to evaluate the assimilation of protein sources in juvenile slipper lobsters (Thenus australiensis)

Stable carbon and nitrogen isotope analyses were used to evaluate the contribution of five protein sources to the growth of juvenile slipper lobster Thenus australiensis. Protein sources tested were fish meal, krill meal, lupin meal, soybean meal and a squid by-product meal. A commercial in confidence basal mix was utilised to produce five experimental feeds containing 30% of each protein source. Juvenile lobsters were fed daily at 5% of their body weight for 12 weeks. Lobster performance was assessed by survival, feed intake and growth performance, and the effects of protein source on nutrient assimilation and discrimination factor were determined. The squid by-product meal, soybean meal, and krill meal produced better growth performance and survival. The specific growth rate on lupin meal was significantly (p < 0.05) lower than all the other protein sources. Apparent feed intake was significantly (p < 0.001) higher in squid by-product meal than lupin meal but with no significant differences in feed efficiency ratio. Protein source assimilation proportion in lobster ranged from 7% for soybean meal to 32% for squid by-product meal, whereby squid by-product meal and fish meal (29%) were the only protein sources assimilated at approximately their dietary inclusion level (30%). Overall, squid by-product meal had the best growth performance, high survival, and the highest assimilation into growth. This study demonstrated the potential of stable isotopic analysis to screen protein sources, evaluate the nutritional performance of the experimental feeds, and provide a deeper insight into ingredient utilisation. This study also provides the first whole-body isotopic discrimination factors for juvenile lobster, which can determine ingredient contribution to growth in future studies.

EFFECT OF BIOACTIVE PROTEIN INGREDIENTS (MOTIVTM) ON TOTAL HEMOCYTE AND SURVIVAL RATE OF VANNAMEI SHRIMP, Litopenaeus vannamei

One of the problematic factors in the cultivation of vannamei shrimp is the outbreak of bacteria and viruses. One way to prevent infection is by strengthening the shrimp’s immune system. MOTIVTM is a fermented corn protein concentrate that has been reported to possess probiotic properties that can positively increase the disease resistance of shrimp. Therefore, this study aimed to determine the effect of bioactive protein (MOTIVTM) on the total hemocyte count and shrimp survival rate. The study used an experimental method with a completely randomized design with five treatments and three replications: A (commercial feed), B (7.5% MOTIV add of 1.5% krill meal instead of 9% fish meal), C (7.5% MOTIVTM add of 1% krill meal to replaces of 2% poultry meal and 6.5% fish meal), D (7.5% MOTIVTM to replaces of 3.5% poultry meal and 4% fish meal), and E (7.5% MOTIVTM to replaces of 7.5% poultry flour). Feeding was done four times/day based on shrimp biomass and weekly feed counts based on daily shrimp survival. The vannamei shrimp used was one gram with a population density of 15 shrimps/aquarium with an aquarium volume of 100 liters.Total shrimp hemocytes, survival, and water quality were all measured. Treatment C had the highest total hemocyte, averaging 4.1 x 107 cells/mL, whereas treatment B had the lowest, averaging 1.4 x 107 cells/mL. During the trial, only treatment C supported 100% survival.

Dietary discrimination using a dual-choice self-feeding system in seabream (Sparus aurata)

Self-feeding systems have been extensively used to study animal behaviour and food preferences in vertebrates. In this study, we used a dual-choice self-feeding system to explore feeding behaviour and dietary discrimination based on organoleptic cues. Experimental tanks were provided with 2 self-feeders activated by string sensors and connected to a computer system. In the first experiment (E1) [6 tanks, 10 animals/tank, body weight (BW) 266 g ± 19.4 g], both feeders delivered the same control standard diet to evaluate the potential preference for one feeder. E1 had 3 phases: 1st, animals were allowed to demand from both feeders; 2nd, from only one feeder and 3rd from both feeders again. The second experiment (E2) (11 tanks, 15 animals/tank, BW range 25–50 g) examined whether seabream can discriminate between 3 isoenergetic diets: the control diet; a positive/palatable diet containing high levels of fish, squid and krill meal; and a negative diet in which 1.5% quinine hydrochloride was added to the control diet. E2 had 3 phases: 1st acclimation with control diet; 2nd dual-choice; 3rd dual-choice with reversal of feeders. The third experiment (E3) (8 tanks, 10 animals/tank, BW range 25-50 g) was performed using a single self-feeder per tank, with each tank being fed either control or quinine diet, to corroborate the aversive response to quinine in the absence of dietary choice. E1 demonstrated that animals demanded significantly less when only one feeder/sensor was available. E2 shows that seabream can easily discriminate a bitter compound (quinine) in the diet, showing negative preference (P < 0.05) in both phases, 2nd and 3rd. When no choice was available (E3), seabream equally demanded control or quinine diet, presumably driven by its energy requirements. However, the presence of the bitter substance increased feed refusals, 14.3% rejection of demanded feed in quinine diet, versus 2.6% in control diet, indicating a role of sensory systems in assessing food quality. A positive conditioning with a palatable diet was not effective and no positive choices were measured over a basal diet, although results were possibly influenced by the previous familiarization with the basal diet and by the experimental conditions (fast growing juveniles at high temperature). This poor dietary selection during active feeding periods could partly explain the easy adaptation of this species to substitution diets. Finally, results suggest that food intake is conditioned by agonistic behaviour in an age-dependent manner. The information will be useful for diet and feeding strategy design in seabream.

Apparent digestibility of protein and essential aminoacids from commonly used feed ingredients in Brazil for juvenile shrimp Litopenaeus vannamei

This study determined the apparent digestibility for crude protein (ACPD) and essential aminoacids (AEAAD) of ingredients for Litopenaeus vannamei fed diets containing soy protein concentrate (SPC), corn gluten meal (CGM), poultry byproduct meal (PBM), meat and bone meal (MBM), hydrolyzed feather meal (HFM), spray-dried blood meal (DBM), tilapia byproduct meal (TBM), Brazilian marine fish meal (BFM), salmon byproduct meal (SLM), and krill meal (KRM). Digestibility was estimated using chromic oxide as a marker in a reference (REF) mixture. Shrimp [...]

Effects of Non-Heated and Heat Processed Krill and Squid Meal-Based Diet on Growth Performance and Biochemical Composition in Juvenile Pacific Bluefin Tuna Thunnus orientalis

This study investigated the effects of krill and squid meal and their heat processing on the growth performance and biochemical composition of juvenile Pacific bluefin tuna (PBT) Thunnus orientalis. An experiment using a 2 × 2 factorial design examined the effects of two dietary protein sources (squid and krill meal) and heat treatment (heated and non-heated). Prey fish were provided to a reference group. Fish with an initial mean weight of 74.1 mg were fed one of the five diets. After six days of the feeding trial, the fish fed with krill meal and non-heated diets showed improved growth compared to those fed with the squid meal and heated diets. Fish fed the non-heated diets showed significantly higher whole-body crude protein and crude lipid contents than fish fed the heated diets. These results suggest that nutrient availability could be improved by using krill meal and the non-heated treatment to improve the growth performance of juvenile PBT.

Effect of fermented corn protein concentrate on growth performance, haemocyte counts, histological structure of hepatopancreas and intestinal condition of pacific white shrimp Litopenaeus vannamei

AbstractThis study evaluated the suitability of commercially produced fermented corn protein concentrate (FCPC) known as MOTIV® (Cargill's IP Product), in replacing fishmeal (FM) and/or poultry by‐product meal (PBM) on growth and health performances of the Pacific white shrimp Litopenaeus vannamei. A 60‐day feeding trial was conducted to evaluate the use of five iso‐nitrogenous and iso‐lipidic diets containing 0% FCPC (control), 7.5% FCPC and 1.5% Krill meal (KM) replacing 9% of FM (FCPC 1), 7.5% FCPC and 1% KM replacing 2% poultry by‐product meal (PBM) and 6.5% FM (FCPC2), 7.5% FCPC replacing 3.5% PBM and 4% FM (FCPC3) and 7.5% FCPC to replace 7.5% PBM (FCPC4) on growth performance, total haemocytes count, lysozyme activity, body composition, resistance on acute salinity change, total number of bacteria and histomorphological condition of the hepatopancreas of Pacific white shrimp Litopenaeus vannamei. At the end of the growth trial, the dietary treatments significantly affect the growth performance of shrimp with better growth obtained in shrimp treated with FCPC 1 and 4 compared to the control treatment. For the non‐specific immune system, the inclusion of FCPC had significantly improved the lysozyme activity of L. vannamei but no significant effect to the total haemocytes counts. Total numbers of bacteria were lower in the hepatopancreas of shrimp fed on FCPC diets compared to the control treatment. In addition, FCPC diets increased survivability of shrimp acute salinity stress compared to the control group. Our findings suggested that FCPC could be used as an alternative for a sustainable approach to replace FM and/or PBM in shrimp diets to have better growth as well as enhancing stress resistances and increasing antibacterial responses of shrimp through enhancing the lysozyme activities in L. vannamei

Optimizing nursery diets for post‐metamorphic stage black sea bass: Growth performance, body composition, and feed utilization on open‐formulated and commercial starter diets

AbstractThe objective of this study was to optimize nursery diets for post‐metamorphic stage black sea bass by evaluating growth performance, whole‐body proximate and fatty acid composition, and utilization of University of North Carolina Wilmington (UNCW)‐formulated and commercial diets under laboratory conditions. A feeding trial was conducted to compare two UNCW‐formulated diets (D1 and D2) for black sea bass (54% crude protein = CP and 14% crude lipid = CL) and two premium, commercial marine finfish fry diets, Otohime (Reed Mariculture Inc., Campbell, CA, CP = 48% and CL = 14%, CD3) and Gemma Diamond (Skretting, Nutreco, Canada, CP = 57%, CL = 15%, CD4). The UNCW‐formulated diet 1 (D1) contained high fish meal (FM, 40% of diet), whereas UNCW‐formulated diet 2 (D2) replaced 50% FM protein by high‐quality poultry by‐product meal (PBM) protein. Post‐metamorphic stage black sea bass (~0.60 g, d40ph) were stocked in each of sixteen 75‐L tanks at a density of 1 fish per L (75 per tank), with four replicate aquaria per treatment. Fish were fed four times per day (0800, 1100, 1400, and 1600 h) to apparent satiation for 30 days. Final body weight (5.70–5.74), specific growth rate (7.40–7.45%/d), and percent body weight gain (834–848%) of fish fed the UNCW‐formulated D1 (FM‐based) and D2 (FM + PBM‐based) were higher (p &lt; .05) than in fish fed the commercial diets CD3 and CD4 (4.66–5.21 g, 6.80–7.15%/d, and 668–756%, respectively). Feed intake (% body weight/d was significantly lower for fish fed commercial diet (CD4) (3.94) compared with fish fed CD3 (4.20), but feed intake for CD3 was not significantly different compared with the UNCW‐formulated diets D1 and D2 (4.10–4.12). Feed conversion ratios (0.76–0.82) were significantly higher for fish fed CD3 (0.82) than for fish fed D1 and CD4 (0.76). Survival was high (99–100%) in all diet treatments. Final whole‐body crude protein content (15.2 to 15.9% wet basis), moisture (68.9–69.6%), and ash (4.31–4.77%) showed no significant differences; however, whole‐body crude lipid was lower in fish fed CD3 (9.67%) than in fish fed the other diets (9.96–10.22%). Final whole‐body fatty acid composition reflected the diet composition. Higher feed consumption and growth of fish fed the UNCW‐formulated diets were attributed to a more optimal combination of marine (fish, squid, and krill meals), terrestrial plant (soybean meal) protein sources, and the addition of chemo‐attractants, which provided both higher nutritional quality and palatability. The study suggests that the species‐specific starter diets may improve growth performance and fingerling quality and may therefore lower production costs under intensive nursery conditions.

Determination of free fatty acids in Antarctic krill meals based on matrix solid phase dispersion

Amino-modified mesoporous silicawas prepared by modifying mesoporous silica with 3-aminopropyltriethoxysilane and used as adsorbents in matrix solid-phase dispersion (MSPD) to analyze free fatty acids (FFAs) in krill meals for the first time. The adsorption–desorption experiments and Fourier-transform infrared spectroscopy showed amino-modified mesoporous silica with ordered mesoporous structure was successfully synthesized. The adsorption experiments including static and dynamic adsorption showed thatabsorption capacity of amino-modified mesoporous silica towards FFAs was better than that of aminated silicon microspheres at all concentrations. Under optimal extraction conditions, outstanding linearity (0.1–12000 nmol g−1), low LODs (0.05–1.25 nmol g−1), satisfactory recoveries (82.17–96.43%) and precisions (0.19–5.26%) were obtained. Moreover, the application of MSPD for FFAs analysis avoided complicated lipid extraction procedures and accomplished the homogenization, crushing, extraction and cleaning of the samples in one step. Consequently, this approach provides an alternative choice to the existing approach for analyzing FFAs in solid and semi-solid samples.

Growth, fatty acid composition, immune-related gene expression, histology and haematology indices of Penaeus vannamei fed graded levels of Antarctic krill meal at two different fishmeal concentrations

An eight-week feeding trial was conducted to investigate the effect of dietary krill meal inclusion in diets with moderate (12%) and low (6%) fishmeal concentrations for Penaeus vannamei. Inasmuch, eight iso‑nitrogenous and isolipidic diets were formulated to contain 36% crude protein and 5.5% crude lipid. In the moderate-fishmeal diets, krill meal was included at 0, 2, 4 and 6% (called FK12:0, FK12:2, FK12:4 and FK12:6, respectively), likewise in the low-fishmeal diets, krill meal was included at the same concentrations of 0–6% (called FK6:0, FK6:2, FK6:4 and FK6:6, respectively). Shrimp with a starting body weight of 0.55 ± 0.02 g were stocked at 22 animals per tank of 350 l capacity and fed three times daily. Results revealed that dietary krill meal and fish meal inclusion levels significantly increased growth performance (P < 0.05)and there was no significant effect on interaction between fishmeal and krill meal levels. Shrimp fed 6% krill meal diet had the highest final body weight of 11.61 g, weight gain of 11.05 g, weight gain % of 1969.38%, specific growth rate of 5.41%/d and yield of 229.42 g/tank. The weight gain % and SGR showed non significant difference between 4 and 6% krill meal containing groups. Dietary change did not affect feed conversion ratio, protein efficiency ratio and apparent protein utilization(P > 0.05). Survival was significantly increased in the groups containing 6 and 4% krill meal diets compared to 0% krill meal diet (P < 0.05). Inclusion levels of krill meal showed non-significant differences in post-fed body composition except for crude lipid and crude fibre content. Fishmeal inclusion levels showed significant (P < 0.05) variation in C14:0, C16:0, C18:0, C16:1,C18:1n-9, C18:2n-6, C22:6n-3, n-3/n-6 ratio, whereas krill meal inclusion levels showed significant variation in the all n-3 fatty acids only. Immune-related gene expression was significantly (P < 0.05) upregulated in the shrimp fed high fishmeal diets (12%) for all the analyzed genes ProPhenoloxidase (ProPO), ProPhenoloxidase activating enzyme (PPAE), Serine Protease (SP), β-1, 3-glucan-binding protein (BGBP), Superoxide dismutase (SOD), and Hemocyanin (HC). The dietary change led to a significant difference in both histology and haematology parameters (P < 0.05). The results inferred that krill meal could be used as a potential functional feed ingredient in Penaeus vannamei.The present study suggested beneficial effects of krill meal in shrimp diets. The levels of fishmeal inclusion (12 and 6%) also showed significant (P < 0.05) variations in various growth performance parameters. It is plausible that an inclusion level of 4% is the minimum for a measurable difference in growth performance.

Effects of Antarctic Krill Products on Feed Intake, Growth Performance, Fillet Quality, and Health in Salmonids

The interest for krill-based ingredients for aquaculture feed applications has increased steadily in recent years. For decades, there has been a heavy reliance on the limited sources of fishmeal and fish oil in the salmonid aquaculture industry. Further growth in farming of carnivorous fish is dependent on new feed resources becoming available. The only unexploited marine resources of significant biomass are found at lower trophic levels, of which the Antarctic krill (Euphausia superba) has a high potential. Apart from being the biggest single species biomass, Antarctic krill is also rich in nutrients, such as omega-3 polyunsaturated fatty acids, phospholipids, astaxanthin, vitamins, and minerals. This makes Antarctic krill a high-quality source of health-beneficial lipids and proteins. The present article provides an overview on the documented benefits of feeding salmonids (Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss)) with krill products (krill meal, krill oil, and krill hydrolysate), focusing on growth performance (feed intake, growth rate, and feed conversion), fillet quality, slaughter yield, and health benefits in terms of reducing fat accumulation in liver and intestinal tissues. Besides, the article discusses possible future studies, to widen the knowledge on krill benefits in salmonids and to unravel the underlying mechanisms.

Evaluation of composite mixture of protein sources in replacing fishmeal for Pacific white shrimp (Litopenaeus vannamei): Based on the changing pattern of growth performance, nutrient metabolism and health status

An 8 weeks feeding trial was designed to evaluate the alternative efficiency of composite mixture of protein sources in replacing fishmeal (FM) for Pacific white shrimp (Litopenaeus vannamei) with the initial weigh of 2.55 ± 0.002 g. Four isonitrogenous (44.0%) and isolipidic (6.7%) diets were formulated using different protein sources. Diet-1 (Control diet): used FM as the main protein sources; Diet-2: 50% FM was replaced by poultry by-product meal(PBM) and antarctic krill meal (AKM) (1:1); Diet-3: FM was totally substituted by PBM, AKM and corn gluten meal (CGM) (1:1:1); Diet-4, 100% FM was substituted by CGM, cottonseed meal and rice protein concentrate meal (1:1:1). Results showed that no statistical differences for growth performance were detected after shrimp fed with Diet-2 and Diet-3 compared with the shrimp fed with control diet. However, Diet-4 markedly decreased the growth performance, feed utilization and body composition. Moreover, compared with control diet, Diet-2 and Diet-3 also had no effect on modifying the concentration of total free essential amino acid (EAA), whereas Diet-4 significantly reduced the concentration of EAA in muscle. Further explored the underlying mechanism, present study shown that Diet-2 did not alter the activation of target of rapamycin (TOR) signaling and the gene expression profile of glucolipid metabolism and immune response. Compared with control diet, Diet-3 caused partial variation of the activity of TOR signaling, nutrient metabolism and immune response. However, whole plant proteins replacement diet (Diet-4) significant decreased the growth performance and damaged the health status through inhibiting TOR signaling and further depressing the nutrient turnover and immune response. According, present study demonstrated that composite mixture of PBM and AKM (1:1) might be an effective substitution to replace FM. Meanwhile, composite mixture of PBM, AKM and CGM (1:1:1) is an excellent alternative diet to totally replaced FM in shrimp feeds.

High protein krill meal as a tool to optimize low cost formulas for juvenile Litopenaeus vannamei diets farmed under semi-intensive conditions

ABSTRACT To investigate the potential of high-protein krill meal (HPK) to improve growth in low-cost diets for Pacific white shrimp (Litopenaeus vannamei), a commercial control and a 3% HPK diet were compared. To simulate a semi-intensive culture system, a total of 4,500 shrimp with a body weight (BW) of 3.07 ± 0.01 g were stocked with 25 animals/m2 in 20 cages in a 2.16-ha pond. After 60 days of rearing, the 3% HPK diet achieved a significantly higher yield (22,094.0 ± 130.35 g/cage) in comparison to the control diet (19,301.6 ± 272.28 g/cage) (P < 0.05). When the feed cost per kg shrimp produced was compared, it was significantly lower in the 3% HPK group (US$1.01/kg shrimp) when compared to the control group (US$1.11/kg shrimp). The results indicate that low feeding cost diets can profit from the partial replacement of fish meal by HPK to optimize shrimp growth performance without increasing formula cost.

Effects of Antarctic Krill Euphausia superba Meal Inclusion on Growth, Body Color, and Composition of Large Yellow Croaker Larimichthys crocea

AbstractThe effects of Antarctic krill Euphausia superba meal inclusion in the diet of Large Yellow Croaker Larimichthys crocea were studied. Inclusion levels were 0.000, 4.125, 8.250, and 12.375% (control, KM4.125, KM8.250, and KM12.375, respectively), and groups of large‐sized fish (average body weight = 190.6 g) received these diets for 99 d. No significant differences were found in body length, body weight, and specific growth rate compared with the control group, but the KM4.125 and KM8.250 groups had significantly increased condition factors and hepatosomatic indices. The KM8.250 fish showed a significant increase in redness values in the dorsal skin, while the KM12.375 fish presented significantly higher yellowness in the ventral skin and tail fin. Addition of krill meal exerted no significant effect on whole‐body proximate composition. The KM8.250 group showed significantly higher lipid content and lower ash content, which differed from those of the KM12.375 group. Most of the amino acids in muscle and liver tissues remained unchanged compared to those in the control. The KM4.125 group showed significantly higher muscle proline, serine, and total functional amino acids, while the total amino acid content in KM12.375 fish significantly decreased. The results indicated that dietary inclusion of fish meal with up to 8.25% krill meal does not result in adverse effects on growth and body composition of large‐sized Large Yellow Croaker; however, addition of krill meal could improve skin coloration in these fish.

Substitution of fish meal with krill meal in rice field eel (Monopterus albus) diets: Effects on growth, immunity, muscle textural quality, and expression of myogenic regulation factors

An 8-week feeding experiment was conducted to evaluate the effects of replacing fish meal (FM) with krill meal (KM) on the growth, immunity, muscle textural quality, and expression of myogenic regulation factors of Monopterus albus (initial body weight: 23.00 ± 0.10 g). Five experimental diets consisted of different proportions of FM (0, 25, 50, 75, and 100 g/kg) were substituted with KM, corresponding to dietary inclusion levels of 0 (KM0), 28.8 g/kg (KM29), 57.6 g/kg (KM58), 86.4 g/kg (KM86), and 115.2 g/kg (KM115). The results showed that: (1) the weight gain rate (WGR) of the fish in the KM58, KM86, and KM115 groups were significantly higher than those of the KM0 group, whereas the opposite result was observed for the feed conversion ratio. (2) Serum complement 3 content and superoxide dismutase activity in the KM58 group and alkaline phosphatase activity in the KM29, KM58, and KM115 groups were significantly higher than those in the KM0 group. However, there were no significant differences in serum immunoglobulin M, complement 4, malondialdehyde content, and catalase activity among all groups. (3) The highest levels of hardness, cohesiveness, springiness, chewiness, gumminess, and adhesiveness of muscle tissues of M. albus fed with the KM58 diet were significantly higher than those of the other treatments. (4) No remarkable difference was detected in MEF2A, MEF2D, MyoG, and Myf5 mRNA expression levels in the muscle tissues among the dietary treatments. However, MyoD2, Myh6, MyoD1, MRF4, MEF2B, and MEF2C mRNA expression levels were significantly upregulated by KM replacement. In conclusion, these results suggested that dietary inclusion levels of 57.6–115.2 g/kg KM improved the growth performance, immune function, muscle textural quality, and expression of myogenic regulation factors of M. albus. Based on the WGR, the optimal level of KM was 103.08 g/kg.

Replacement of fish meal by Antarctic krill meal in diets for European sea bass Dicentrarchus labrax: Growth performance, feed utilization and liver lipid metabolism

A sustainable growth of the aquaculture sector implies the use of sustainable novel raw materials as replacers of the traditional fishmeal (FM) and fish oil (FO) ingredients. This fact has led to the development of sustainable and functional diets as part of a management strategy to reduce the effects on fish growth performance and health derived from low FM/FO dietary contents. In this sense, Antarctic krill (Euphausia superba) is considered a potential candidate in dietary inclusions to potentiate fish growth and health status. In this study, European sea bass (Dicentrarchus labrax) were fed a practical diet with either a 15% fishmeal content (KM0; control diet) or the same diet substituted by 30% (KM5; 50 g KM/kg diet) or 50% (KM7.5; 75 g KM/kg diet) Antarctic krill meal (KM) for 12 weeks in triplicates. At the end of the feeding trial, growth performance, liver morphology, liver proximate composition, lipid classes and fatty acid profiles, as well as the expression of hepatic genes related with lipid metabolism were evaluated. Fish fed KM-based diets presented higher (p < 0.05) final weight, protein and lipid efficiency ratios, specific growth rate (SGR) and improved feed conversion ratio (FCR), irrespective of the KM dietary level. Whole body and muscle proximate composition and fatty acid profiles were similar among dietary groups. Livers of European sea bass fed the experimental diets presented similar (p > 0.05) biochemical composition and fatty acid profile. However, smaller hepatocellular area and lower grade of cytoplasm vacuolization as well as a better alignment around sinusoidal spaces were found. The analyses of liver lipid classes revealed a positive correlation between the level of dietary KM and the pigmented material such as astaxanthin and free fatty acid content, as well as a negative correlation with the cholesterol levels. The expression of hepatic genes studied demonstrated a downregulation of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (hmgr) and delta-6-desaturase (fads2) expression levels in fish fed KM-based diets. Besides, gene expression levels of fatty acid binding protein 7 (fabp7) and lipoprotein lipase (lpl) were significantly correlated with KM dietary levels. Altogether, these results profile KM as a potential promoter of growth and liver health in European sea bass fed low fish meal and oil diets.

Effect of Boiling Process on the Quality of Antarctic Krill Meal

Boiled processing is a common process in the production of Antarctic krill meal, and its processing conditions often affect the physical and chemical indicators of Antarctic krill meal. In order to further study the effect of boiling processing on the quality of Antarctic krill meal, this study measured the lipid peroxide value, acid value, thiobarbituric acid value (TBARS) and fatty acid of krill meal after different temperature and time treatments. The experimental results showed that compared with the non-boiling treatment group, the peroxide value, acid value and TBARS of the 40, 60, 80, and 100 ℃ were increased significantly (P 0.05). Boiling for 15, 30, 45, and 60 minutes all increased the lipid peroxidation value of Antarctic krill meal (P 0.05). And boiling time over 30 min significantly increased acid value (P<0.05). More than 30 min boiling treatments slightly increased the content of saturated fatty acids. The 60 min boiling reduced the content of polyunsaturated fatty acids from 47.186% to 43.342%. Considering comprehensively, to get better Antarctic krill meal, the boiling temperature should be controlled at 60 °C as much as possible, and the boiling time should not exceed 30 minutes.

Effects of fishmeal replacement, attractants, and taurine removal on juvenile and sub-adult Red Snapper (Lutjanus campechanus)

Four growth trials were conducted to evaluate the effects of fishmeal replacement with various levels of soybean meal (SBM) and poultry byproduct meal (PBM) on growth performance in practical diets for juvenile and sub-adult red snapper, Lutjanus campechanus. In addition, the need for taurine and palatability enhancement (krill meal) were evaluated in the high SBM, low fishmeal diet. Across the trials, ten diets were formulated to contain 36% protein and 10% lipids. All diets except for one included a taurine supplement of 1%. A supplement of 5% krill meal was added as an attractant to one of the low fishmeal and high SBM diets to explore potential palatability issues associated with plant-based proteins. No statistically significant differences were found between the performance of the basal diet and the PBM replacement diets, indicating that PBM is a suitable replacement for fishmeal in red snapper diets. On the contrary, a clear negative linear relationship was observed with increasing levels of SBM replacement. The reduced growth performance of high SBM inclusion diets is unlikely to be due to palatability issues, as no significant difference was observed between the performance of the high SBM diet with krill meal and an identical diet without krill meal. The significant reduction in growth observed in snapper fed a diet lacking a taurine supplement indicates that red snapper have a taurine requirement that is limiting at low (0.2%) levels. Gut samples were taken from fish that received the SBM diets to determine if reduced growth performance could be attributed to inflammation. However, no statistically significant difference was observed, indicating that reduced growth was not necessarily the result of a hypersensitivity reaction. Further investigation will be necessary to determine the optimal taurine requirement and required dietary supplements to improve the performance of low fishmeal feed formulations.