Published on 24/3/2017
Three isonitrogenous diets containing 60 g kg–1, 90 g kg–1 or 120 g kg–1 lipid were formulated and fed to the Litopenaeus vannamei (2.00 ± 0.08 g) under two salinities (25 or 3 psu) in triplicate for 8 weeks. Shrimp fed 90 g kg–1 lipid had higher weight gain and specific growth rate than shrimp fed the other two diets regardless of salinity, and the hepatosomatic index increased with increasing dietary lipid at both salinities. The shrimp at 3 psu had significantly lower survival and ash content, higher condition factor, weight gain and specific growth rate than the shrimp at 25 psu. Increasing dietary lipid level induced the accumulation of serum MDA regardless of salinity, and at 3 psu, it reduced the serum GOT and GPT activities and the mRNA expression of TNF-α in intestine and gill of L. vannamei. The hepatopancreatic triacylglycerol lipase (TGL) and CPT-1 mRNA expression showed the highest value in shrimp fed 90 g kg–1 lipid diet at 3 psu. This study indicates that 120 g kg–1 dietary lipid may negatively affect the growth and induce oxidative damage in shrimp, but can improve immune defence at low salinity; 60 g kg–1 dietary lipid cannot afford the growth and either has no positive impact on the immunology for L. vannamei at 3 psu.
Published on 24/3/2017
An 8-week feeding trial was conducted to investigate the effects of dietary vitamin E on growth performance and antioxidant status of juvenile snakehead. The snakeheads (20.47 ± 0.06 g) were fed with five isonitrogenous and isoenergetic experimental diets that contained 13 (the basal diet), 52, 79, 168 and 326 mg of vitamin E kg−1, respectively. The maximum specific growth rate (SGR) and feed intake (FI) were achieved in fish fed on a diet with 79 mg kg−1 vitamin E (p < .05). No significant differences were found in protein efficiency ratio (PER), feed conversion ratio (FCR) and survival of fish among all groups (p > .05). Vitamin E supplementation improved hepatic glutathione peroxidase (GPx) activity significantly. A consistent decline in the hepatic and serum malondialdehyde (MDA) content was observed in fish fed diets with the increased supplementation of vitamin E (p < .05). In addition, with the increasing level of vitamin E, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were reduced (p < .05). However, serum superoxide dismutase (SOD), catalase (CAT) and alkaline phosphatase (ALP) activities were enhanced in fish fed 79 mg vitamin E kg−1 diet and then decreased significantly as the content of vitamin E in the diet increased (p < .05). Meanwhile, serum albumin (ALB) and globulin (GLB) were not affected by the supplemental levels of dietary vitamin E (p > .05). The vitamin E concentrations in liver and serum increased significantly with increasing dietary vitamin E (p < .05). Based on the broken-line regression of SGR, vitamin E level in the diet is estimated to be 80.5 mg kg−1 for Channa argus × Channa maculata. In conclusion, this study indicated that the dietary appropriate vitamin E could enhance the growth performance, antioxidant status and non-specific immune response.
Published on 22/3/2017
Soybean meal (SBM) is one of the most commonly used vegetable ingredient to replace fish meal in fish diets. However, SBM is limiting in some essential amino acids and contains numerous antinutritional factors and antigens that can affect intestinal microbiota and innate immune system in several finfish species and crustaceans and compromise health. The impact of SBM on health and gut microbiota of aquatic animals is not only affected by SBM in general, but also on the degree of treatment of the meal and exposure. Recently, many studies are actively seeking ways to complement or balance those adverse responses induced by high inclusion of SBM in aquaculture diets. These include advanced processing and mixture of feed with other feed components to balance antinutritional factors. The impact of dietary soybean oil on gut microbiota has also been investigated but to a lesser extent than SBM. As the gastrointestinal tract has been suggested as one of the major routes of infection in finfish species and crustaceans, the effect of soybean products on the gut microbiota is important to investigate. Several studies have focus on supplementation of SBM on the adverse responses of the innate immune system as immunological mechanisms are likely involved in the underlying pathology. However, the precise cause of the inflammatory process has not yet been clarified, even though some investigations have suggested that alcohol-soluble antinutritional factors, especially soy saponins, are potential causative factors. Possible interactions between soybean products and innate immune system in several finfish species and crustaceans are discussed.
Published on 17/3/2017
Four isocaloric-isonitrogenous diets containing 0, 50, 100 and 190 g/kg corn protein concentrate (CPC) as replacement for dietary fish meal were fed to Nile tilapia Oreochromis niloticus fingerlings for 8 weeks. Tilapia growth parameters were not significantly (p > .05) different in fish fed diets with 0, 50 and 100 g/kg CPC and found to be superior compared to those fed on 190 g/kg CPC. Fish dressing ratios and body composition were similar among all treatments. The electron microscope indicated that the stomach size of control fish was slightly smaller and the wall was thinner while the stomach of the fish fed all other levels of CPC undergone a remarkable size increase and their walls were thicker after feeding diets with CPC. Total aerobic bacterial and coliform counts were significantly decreased in fish intestine when fed diets with 100 and 190 g/kg CPC compared with fish fed diets with 0 g/kg or 50 g/kg CPC. This study indicates that it is possible to replace up to 534 g/kg of dietary fish meal in tilapia fingerlings using 100 g/kg of CPC without any negative effect on fish growth and proximate body composition.
Published on 17/3/2017
A feeding trial was conducted to evaluate the optimum dietary level of eicosapentaenoic acid (EPA, 20:5n-3) based on growth and non-specific immune responses in juvenile rock bream. A basal diet without EPA supplementation was used as a control, and six other diets were prepared by supplementing with 4, 8, 12, 16, 20 or 40 g of EPA per kg diet. The actual EPA concentrations of the diets were 0.5, 4.3, 8.5, 13.0, 16.8, 21.0 and 41.2 g of EPA per kg diet, and the diets were abbreviated as EPA0.5, EPA4.3, EPA8.5, EPA13.0, EPA16.8, EPA21.0 and EPA41.2, respectively. Triplicate groups of fish averaging 1.06 ± 0.01 g (mean ± SD) were fed one of the seven experimental diets at the apparent satiation for 8 weeks. At the end of the feeding trial, weight gain, specific growth rate and feed efficiency of fish fed EPA16.8, EPA21.0 and EPA41.2 diets were significantly higher than those of fish fed EPA0.5, EPA4.3, EPA8.5 and EPA13.0 diets (p < .05). Superoxide dismutase activity of fish fed EPA16.8, EPA21.0 and EPA41.2 diets were significantly higher than those of fish fed EPA0.5, EPA4.3 and EPA8.5 diets. Fish fed EPA21.0 and EPA41.2 diets showed significantly higher lysozyme activity than did fish fed EPA0.5, EPA4.3, EPA8.5 and EPA13.0 diets. The broken-line analysis of weight gain indicated that the optimum dietary EPA level was 16.7 g/kg diet. These results suggested that the optimum dietary EPA level in juvenile rock bream could be greater than 16.7 g/kg diet but less than or equal to 16.8 g/kg diet based on the broken-line analysis and the ANOVA test of weight gain.
Published on 17/3/2017
A 10-week feeding trial of using housefly (Musca domestica) maggot meal (MM) in practical feeds for Nile tilapia (Oreochromis niloticus) was conducted to assess the growth performance, ingredient utilization, flesh quality, innate immunity and its influence on water environment. Fish were fed five isonitrogenous and isoenergetic diets, where fishmeal (FM) was substituted by MM at the level of 0, 90, 180, 270 and 360 g kg-1 diet (remaining FM content: 360, 270, 180, 90 and 0 g kg-1). There was no significant difference in feed intake and apparent digestibility coefficient between the treatments. Replacing up to 270 g kg-1 FM did not have an impact on the growth performance and ingredient utilization, whereas the complete replacement of FM caused significantly lower survival rate, weight gain, specific growth rate and higher feed conversion rate. Dietary MM was also proved positively influential in flesh quality, whereas replacing 180 g kg-1 or more FM suppressed the innate immunity of tilapia. When compared by the effects on the water environment, the increasing substitute levels were accompanied with the declining concentrations of nitrite nitrogen and total phosphorus in the water. Our study verified the feasibility of using MM as a partial substitute of FM in aquatic feed. When replacing 180 g kg-1 FM (corresponding to half of the FM content in control diet) in the diet of Nile tilapia, it can serve as a renewable and environmentally superior alternative without compromising the performance criteria.
Published on 17/3/2017
Studies were conducted to investigate the effects of dietary n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) on growth performance, lipid deposition, hepatic fatty acid composition and serum enzyme activities of juvenile Japanese seabass Lateolabrax japonicus (initial mean weight 29.2 ± 1.34 g). Triplicate groups of 30 Japanese seabass were fed with six diets containing grade levels of n-3 LC-PUFA (1.30, 2.98, 5.64, 10.31, 14.51, 24.13 g kg–1 of dry weight) to apparent satiation twice daily for 9 weeks. The specific growth rate (SGR) was the highest in 10.31 g kg–1 dietary n-3 LC-PUFA group. Crude lipid content of the fish decreased significantly with increasing dietary n-3 LC-PUFA. Meanwhile, the hepatic lipid content increased significantly in the 24.13 g kg–1 group. Hepatic n-3 LC-PUFA content of total fatty acids was closely correlated with that in diet. No significant difference was observed in serum alanine transaminase (ALT) and aspartate aminotransferase (AST) activities. Moderate n-3 LC-PUFA level (10.31 g kg–1 of dry weight) in the diet was beneficial to enhance the activity of lysozyme in serum. Based on SGR, the optimum dietary n-3 LC-PUFA content was estimated to be around 10.94 g kg–1 of dry weight by second-order polynomial regression method.
Published on 17/3/2017
Roasted coffee powder (RCP; Coffea arabica) is usually used as a beverage for human but there are few attempts to use it as a natural feed supplement in fish diets. In this study, common carp, Cyprinus carpio L., (11.8 ± 0.09 g) were reared in zinc (Zn)-containing water at concentrations of 0.0 or 5.0 mg/L and cosupplemented with 0.0 or 1.0 g RCP/kg diet for 6 weeks to investigate effects of RCP supplementation, Zn exposure and their interaction on fish performance, biochemical variables, antioxidant activity and Zn bioaccumulation in whole fish body. Fish growth and feed intake were significantly affected by RCP supplementation, Zn toxicity and their interaction. However, fish fed a RCP-supplemented diet did not exhibit better performance than those fed the RCP-free diet and both diets produced higher fish performance than the Zn-toxicated fish. It is noticed that RCP supplementation to Zn-toxicated fish enhanced their growth, and feed utilization as compared to Zn-toxicated fish alone. Fish fed control and RCP-enriched diets showed no significant differences in biochemical variables, which were significantly altered due to waterborne Zn toxicity. Moreover, Zn reduced significantly; meanwhile, RCP supplementation increased significantly superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities. Notably, Zn exposure could reduce fish growth and antioxidant activity and increase Zn deposition in whole fish body. And RCP intake could enhance the antioxidant activity exerting a protective effect against Zn toxicity, thereby reducing Zn bioaccumulation in whole fish body.
Published on 16/3/2017
Taurine is an important amino acid derivative for marine and freshwater fish, especially during early development. We investigated the range of taurine concentrations that influence the growth and survival rates of California yellowtail (CYT; Seriola dorsalis) during transition from live feeds to microparticulate diets, as well as the extent to which nutrient leaching from the microparticulate diets affects these ranges. We tested particle-assisted rotationally agglomerated (PARA) particles with four levels of taurine: 4 (low taurine; LT), 45 (medium taurine; MT), 93 (high taurine; HT) and 122 g/kg (very high taurine; VHT). Our results showed that CYT postlarvae had no significant differences in growth, survival and feed consumption rates between the MT, HT and VHT treatments. However, it should be noted that the PARA particles containing 122 g/kg (VHT) taurine were especially prone to leaching and may have had taurine concentrations as low as 34.9 g/kg before they settled on the bottom of the tank. Therefore, the actual dietary taurine concentrations experienced by the larvae were likely lower than the initial dietary concentrations. More research is needed to evaluate the potential nutrient toxicity of elevated dietary taurine concentrations for marine fish larvae and juveniles.
Published on 11/3/2017
The effects of two weaning diets and different weaning protocols on growth, survival, skeletal deformity and gut morphology of Atlantic cod larvae were studied in four groups from 16 to 45 days posthatch (dph). Cod larvae in groups 1 (early weaning with control diet) and 2 (early weaning with experimental diet) were used to evaluate the effects of different polar lipid content of weaning diets on larval and juvenile performance. Cod larvae in groups 2, 3 (early weaning with experimental diet + cofeeding with Artemia) and 4 (earlier weaning with experimental diet and earlier cofeeding with Artemia) were used to evaluate the effects of early introduction of dry diet and Artemia. From 45 to 170 dph, cod juveniles from all four groups were reared using a standard feeding protocol. No significant differences in growth, survival, deformities and gut morphology were found between cod larvae and juveniles from groups 1 and 2. Cod larvae fed on cofeeding regime with Artemia nauplii (groups 3 and 4) were bigger and had lower frequencies of jaw and neck deformities and higher foregut microvillus circumference than cod larvae from group 2. Our results demonstrate the importance of proper weaning protocols in producing better quality cod juveniles.
Published on 11/3/2017
Marine-derived fish meal (FM) is a traditional component of commercial aquaculture feeds for many farmed fish species. Modern bioprocessing technologies have been developed to produce high-protein plant-based ingredients for aquafeeds to further reduce FM and other conventional animal protein sources. A 90-day feeding trial using juvenile rainbow trout (Oncorhynchus mykiss) (27.9 ± 1.4 g; mean ± SE) was completed to evaluate growth, feed efficiency, general health and immunological responses to diets containing experimental plant-based protein sources and reduced FM. Trout were fed one of four dietary treatments: experimental bioprocessed soy protein concentrate (BSPC), commercially available enzymatically hydrolysed soy protein concentrate (CSPC), experimental bioprocessed barley protein concentrate (BBPC) and a FM control (FMC). At trial termination, there were no significant differences in relative growth (RG) or specific growth rate (SGR) between fish fed either FMC or BSPC (p > .05). Fish fed either CSPC or BBPC resulted in significantly lower RG and SGR than the FMC (p < .05). Significant respiratory burst analysis differences were observed among treatments at day 90 (p < .01), for fish fed either FMC or CSPC diets. This assessment of bioprocessed plant-based protein ingredients facilitates the characterization and incorporation of bioprocessed soy and barley protein as the industry continues to evaluate FM replacements in rainbow trout feeds.
Published on 8/3/2017
Six isoenergetic diets were formulated as follows: fish meal (FM) 700 g kg–1 (control, C), FM 300 g kg–1 + soy protein concentrate 300 g kg–1 (SPC), FM 300 g kg–1 + enzyme-treated SPC 300 g kg–1 (ESC), FM 170 g kg–1 + soy protein isolate 300 g kg–1 (SPI), FM 160 g kg–1 + enzyme-treated SPI 300 g kg–1 (ESI) and FM 150 g kg–1 + conglycinin 300 g kg–1(CG). Forty fish (3.9 g) were randomly distributed into each of eighteen 300-L tanks, fed twice daily until satiation for 8 weeks. The final body weight, specific growth rate and condition factor did not show significant differences among the fish fed with diets C, SPC, ESC and ESI (p > .05). The survival was significantly lower in fish fed with diets SPI and CG. Feed efficiency was significantly higher in fish fed with diets SPC and C than in fish fed with other diets (p < .05). There were no significant differences in nutrients retention efficiencies in fish fed with diets C, SPC, ESC and ESI. A significantly higher phosphorus retention efficiency in fish fed with soymilk protein diets resulted in lower phosphorus discharge to the environment (p < .05). These results suggest that the soymilk proteins can comfortably replace 570–770 g FM kg–1 diet of red sea bream juvenile, which will ensure significant ecological benefits through reducing phosphorus load to the environment.
Published on 8/3/2017
A 6-week feeding trial was conducted to estimate the optimum dietary essential amino acid (EAA) pattern for silvery-black porgy juvenile based on the AA deletion method. Eleven isonitrogenous and isoenergetic diets were formulated containing 60% of fish meal nitrogen and 40% of crystalline AA nitrogen. In the control diet, the EAA profile was made similar to fish meal protein. Ten other diets were formulated similar to the control diet but replacing 40% of each EAA by a mixture of non-essential amino acids. Triplicate groups of fish (initial body weight of 4.7 g) were handfed with the experimental diets, three times a day, to visual satiation, for 42 days. At the end of the trial, final body weight of all EAA-deficient groups was lower than that of control group, ranging from 6.3% of reduction with arginine-deficient diet to 39.4% of reduction with lysine-deficient diet, relatively to the control group. Based on the relationship between nitrogen retention and EAA intake of the control and EAA-deficient diets, the optimal dietary EAA profile for silvery-black porgy juveniles was estimated to be (g 16/g N): arginine 5.3, lysine 6.0, threonine 5.2, histidine 2.5, isoleucine 4.6, leucine 5.4, methionine + cysteine 4.0 (in a diet containing 0.6 cysteine), phenylalanine + tyrosine 5.6 (in a diet containing 1.9 tyrosine), tryptophan 1.0 and valine 4.6.
Published on 6/3/2017
A range of physical cell disruption techniques have been evaluated to aid the processing of astaxanthin-rich haematocysts of Haematococcus pluvialis for inclusion in salmonid feeds. Cell disruption by a scalable pressure treatment system was shown to be effective in breaking open the haematocysts without altering the content or isomeric composition of carotenoids in the algal cells. Storage of disrupted cells was optimal at −20°C in the dark under nitrogen. Disrupted cells were spray-dried, incorporated into commercial diets and fed to rainbow trout (Oncorhynchus mykiss L.). A marketable level of pigmentation in fish muscle was achieved after 10-week dietary supplementation. The geometric and optimal isomer composition of the astaxanthin deposited in the muscle was nearly identical to that seen in Haematococcus. Changes were observed in the chirality of the astaxanthin deposited in the skin in comparison with that isolated from both the white muscle and the alga.
Published on 6/3/2017
4-Nonylphenol (NP) is an emerging concern contaminant which is widely spread in the aquatic ecosystem. Nigella sativa seed (NSS) has multifaceted therapeutic values. This study aimed to give insight into the potential protective effect of NSS on NP-induced haematotoxicity in Clarias gariepinus through evaluation of haematological parameters, oxidant/antioxidant balance of blood lysate and histopathological investigation of blood smear. One hundred and fifty fish were divided into five groups (30/group). First group served as control which did not received NP exposure and fed basal diet without NSS supplementation. The other four groups were exposed to NP at a dose of 0.1 mg L−1 and fed diets supplemented with NSS at levels of 0, 10, 25 and 50 g/kg diet, respectively. Macrocytic hypochromic anaemia, thrombocytopenia, leucopenia, neutrophilia, lymphopenia, monocytosis and eosinophilia were observed following NP exposure together with increase in morphological erythrocyte alterations and micronuclei formation. Elevation in total peroxide and malondialdehyde and depletion in total antioxidant capacity of blood lysate were reported. We concluded that supplementation of NSS markedly ameliorated the previously listed manifestations, and the most effective doses were 25 and 50 g/kg feed.
Published on 6/3/2017
Litopenaeus vannamei is economically important shrimp species in worldwide aquaculture. This study was conducted to assess the effect of different levels of probiotic Pediococcus pentosaceus (PP) on growth performance, feed utilization, digestive enzyme activity, intestinal microflora count and body composition of L. vannamei. Four diets containing different concentrations [0 (PP0), 106 (PPI), 107 (PPII) and 108 (PPIII) CFU/g] of PP were formulated. After 8 weeks feeding trial, the experimental shrimps were challenged with Vibrio anguillarum and noted the surveillance. At the end of the feeding trial, the obtained results revealed a significant increase (p < .05) in final body weight, final length, weight gain (WG), survival rate, protease and amylase activities, lactobacillus sp. and Bacillus sp. intestinal count, total haemocyte counts (THC) and lysozyme activity in PPIII group when compared with the other groups. Similarly, WG, amylase activity, Bacillus sp. count, THC and lysozyme activity were significantly enhanced in case of PPII compared to the control group (p < .05). Interestingly, FCR and Vibrio sp. counts were significantly decreased in case of PPIII group when compared to the other groups (p < .05). Also, significant level of surveillance was noted in the challenging test with V. anguillarum. These results suggested that the P. pentosaceus improved the growth performance, digestive enzyme activity, immunity and tolerance against V. anguillarum of L. vannamei.
Published on 6/3/2017
In a 4-week experiment, 15 cannulated rainbow trout were fed three diets based on fish meal (FM), Saccharomyces cerevisiae yeast (SC) and Wickerhamomyces anomalus and S. cerevisiae yeast mix (WA). Fish were fed daily, and blood samples were collected on day 7 of each week at 0, 3, 6, 12 and 24 hr after feeding. In the final week, fish were exposed to a 1-min netting stressor. All essential and non-essential plasma amino acid levels except methionine were similar between fish fed diets FM, SC and WA. Plasma methionine and sarcosine were significantly higher in fish fed diets SC and WA, possibly due to the crystalline methionine level, form or feeding regime. Hydroxy-proline and 3-methyl-histidine were higher in fish fed diet FM, which can be explained by the higher levels present in fish meal compared with yeast. In stressed fish, there were no dietary effects on plasma amino acid levels, but significant increases in taurine and cystathionine were found in stressed compared with unstressed fish. These results demonstrate that yeast-based diets produce similar plasma amino acid profiles to fish meal and suggest that yeast may be a suitable fish meal replacement in diets for rainbow trout.
Published on 6/3/2017
Published on 3/3/2017
The objective of this study was to evaluate the effects of different phospholipids (PL) and cholesterol (CH) levels on the growth, moulting and fatty acid composition of juvenile swimming crab, Portunus trituberculatus. Six diets were designed to contain three PL levels (0, 10 and 20 g/kg) and two CH levels (2 and 8 g/kg). Juvenile swimming crabs (3.48 ± 0.02 g/crab) were reared for 8 weeks. The weight gain (WG) was significantly (p < .05) increased by supplementation of 8 g CH/kg of diet. However, no significant interaction between dietary PL and CH levels was found on the growth performance (p > .05). The moulting frequency (MF), protein efficiency ratio (PER) and feed efficiency ratio (FCR) were not significantly (p > .05) affected by the dietary treatments. The serum total cholesterol (TCH) significantly (p > .05) increased with increasing dietary PL level. The C20:4n-6 and C20:5n-3 content of the whole body of crabs increased with the addition of PL to the diet containing 2 g/kg CH of diet. An interaction was observed between PL and CH on certain saturated and unsaturated fatty acid concentrations of body.
Published on 3/3/2017
A ten-week feeding trial was conducted to evaluate the effect of replacing fishmeal with two differently processed cottonseed meals (CSM), namely XC and SC, separately in turbot (5.28 ± 0.02 g). Nine isonitrogenous and isoenergetic diets were formulated without fishmeal replacement (FM), 150 g/kg (XC15, SC15), 250 g/kg (XC25, SC25), 350 g/kg (XC35, SC35) and 450 g/kg (XC45, SC45) of fishmeal replaced by CSM. Fishmeal was successfully replaced by XC in turbot diets without growth reduction at 350 g/kg, but not by SC even at 150 g/kg. The apparent digestibility coefficients of SC-included diets were significantly lower than XC-included diets at same replacement level. The activities of aspartate aminotransferase and superoxide dismutase were significantly affected in XC45 and SC45 group. The XC45 and SC-included diets caused shortened distal intestine villi height and structural damage of liver compared with FM diet. This study indicated that different processing methods could affect the nutritional value of CSM and effect as a protein source for turbot. CSM with high quality could be an important alternative dietary protein source for juvenile turbot.