Levels Of Fish Meal Research Articles

Effects of replacing fish meal with rubber seed meal on growth, nutrient utilization, and cholesterol metabolism of tilapia (Oreochromis niloticus × O. aureus).

A feeding trial was conducted to evaluate the effects of replacing fish meal with rubber seed meal (RSM) on growth, nutrient utilization, and cholesterol metabolism of tilapia (Oreochromis niloticus × Oreochromis aureus). Five experimental diets were formulated with 0, 150, 300, 450, and 600gkg-1 RSM replacing graded levels of fish meal, respectively. Each diet was randomly assigned to triplicate groups of 25 fish (initial average weight 65.3g) per aquarium in a rearing system maintained at 29±1°C for 8weeks. Dietary 150gkg-1 RSM inclusion did not affect the weight gain and daily growth coefficient, whereas these were depressed by a further inclusion. Additionally, feed efficiency ratio and protein efficiency ratio were not affected by dietary RSM inclusion regardless of inclusion level. However, the inclusion of 450 and 600gkg-1 RSM decreased the mid-intestinal trypsin, lipase, and amylase activities; the hepatic acyl-CoA/cholesterol acyl transferase; low-density lipoprotein receptor; and 3-hydroxy-3-methyl-glutaryl-CoA reductase activities. Similarly, dietary 600gkg-1 RSM inclusion inhibited the plasma catalase and hepatic glutathione peroxidase activities. These results indicated that 150gkg-1 RSM can be included in tilapia diets, whereas higher inclusion of RSM inhibited the growth rate, digestive enzyme activity, antioxidant capacity, and cholesterol metabolism.

Disease resistance and response against Vibrio anguillarum intestinal infection in European seabass (Dicentrarchus labrax) fed low fish meal and fish oil diets

The aim of this study was to assess the effects of low levels of dietary fish meal (FM) and fish oil (FO) on disease resistance and gut associated lymphoid tissue (GALT) response after an experimental intestinal infection with V. anguillarum in European sea bass (Dicentrarchus labrax) For that purpose, sea bass juveniles were fed one of four diets containing combined levels of FO and FM as follows: 20%FM/6%FO, 20%FM/3%FO, 5%FM/6%FO and 5%FM/3%FO during 153 days. At the end of the feeding trial, fish were subjected to either an in vivo exposure to a sub-lethal dose of V. anguillarum via anal inoculation or to an ex vivo exposure to V. anguillarum. Additionally, inducible nitric oxide synthase (iNOS) and tumor necrosis factor α (TNFα) gut patterns of immunopositivity were studied. Growth performance was affected by dietary FM level, however ex vivo gut bacterial translocation rates and survival after the in vivo challenge test were affected by dietary FO level. After 5 months of feeding, low dietary FM levels led to a posterior gut up-regulation of interleukin-1β (IL-1β) and TNFα, major histocompatibility complex-II (MHCII) and cyclooxygenase-2 (COX2), which in turn reduced the gut associated lymphoid tissue (GALT) capacity of response after 24 h post infection and conditioned European sea bass capacity to recover gut homeostasis 7 days post infection. Immunoreactivity to anti-iNOS and anti-TNFα presented a gradient of increased immunopositivity towards the anus, regardless of the dietary FM/FO fed. Strong positive anti-TNFα isolated enterocytes were observed in the anterior gut in relation to low levels of dietary FM/FO. Submucosa and lamina propria immunoreactivity grade was related to the amount of leucocyte populations infiltrated and goblet cells presented immunopositivity to anti-iNOS but not to anti-TNFα. Thus, reducing FO content from 6% to a 3% by VO in European sea bass diets increases ex vivo and in vivo gut bacterial translocation rates, whereas reducing FM content from 20% down to 5% up-regulates the expression of several posterior gut inflammation-related genes conditioning fish growth and GALT capacity of response after bacterial infection.

Combined replacement of fishmeal and fish oil in European sea bass (Dicentrarchus labrax): Production performance, tissue composition and liver morphology

The aim of this study was to evaluate the combination of maximum replacement of fishmeal (FM) and fish oil (FO) by alternative meals (AM) and oils (AO) to develop nutritious, but more eco-friendly diets for European sea bass (Dicentrarchus labrax) juveniles. European sea bass of 9.8±1.5g and 9.1±0.5cm were fed nine isonitrogenous (45% crude protein) and isolipidic (21%) diets containing gradually reduced levels of FM and FO as follows (%FM/%FO): 58/15, 20/6, 20/3, 10/6, 10/3, 5/6, 5/3 and 0/0. Another diet, 0/0+, was similar to the 0/0 but supplemented with LC-PUFA from microbial and marine sources. After 90 days of feeding, European sea bass fed the 0/0 diet showed reduced (P<0.05) final weight, final length, condition factor, perivisceral fat index and viscero-somatic index as well as feed efficiency, whereas addition of LC-PUFA significantly improved daily growth index (DGI) (0/0+ diet). Reduction of FM/FO down to 5/3 did not significantly affect fish survival or condition factor, whereas reduction to 5/6 did neither affect sea bass length or feed conversion and reduction down to 10/3 did not affected body weight, DGI and perivisceral fat or visceral weight. FM reductions down to 5% significantly reduced growth rate. FO substitution by vegetable oils (VO) led to reduced growth and increased liver to body weight ratios, liver lipid deposition and hepatocellular size. In liver and muscle, FO substitution increased n-6 fatty acids (FA) and n-6/n-3 ratio and reduced saturated FA and n-3 LC-PUFA, whereas monounsaturated FA were not increased in proportion to dietary contents. Moreover, FO reduction increased the products from Δ6 desaturase and elongases, Elovl6 and Elovl5. In conclusion, the results of this study show that it is possible to reduce dietary FM and FO levels down to 10% and 3% in mostly plant-based diets without affecting growth performance of European sea bass juveniles.

Replacement of Fishmeal with a Blend of Poultry Byproduct Meal and Soybean Meal in Diets for Largemouth Bass, Micropterus salmoides

AbstractA feeding trial was conducted to evaluate the potential of replacing fishmeal with poultry byproduct meal (PBM) and soybean meal in diets for largemouth bass, Micropterus salmoides. A reference diet (C) contained 400 g/kg fishmeal, and 40 or 60% of the fishmeal was replaced with a blend of pet‐food‐grade PBM and soybean meal (diets PP1 and PP2) or a blend of feed‐grade PBM and soybean meal (diets PF1 and PF2). No significant differences were found in weight gain, nitrogen retention efficiency (NRE), condition factor, and body composition among fish fed diets PP1, PP2, PF1, and PF2. Feed intake and feed conversion ratio (FCR) were higher in fish fed diet PF1 than in fish fed diet PP1. No significant differences were found in weight gain, NRE, condition factor, and body composition between fish fed diet C and diets PP1, PP2, PF1, and PF2. The feed intake and FCR were lower in fish fed diet C than in fish fed diets PP2, PF1, and PF2. This study reveals that dietary fishmeal level for largemouth bass could be reduced to 160 g/kg by inclusion of PBM and soybean meal in combination.

Effects of fish meal replacement with meat and bone meal using garlic(Allium sativum) powder on growth, feeding, digestive enzymes and apparent digestibility of nutrients and fatty acids in juvenile rainbow trout (Oncorhynchus mykissWalbaum, 1792)

Effects of graded dietary levels of fish meal (FM) replacement with meat and bone meal (MBM) with garlic powder (G) or without garlic powder (WG) garlic powder were investigated on growth, digestive enzymes, apparent digestibility, body composition and fatty acid profile of juvenile rainbow trout (Oncorynchus mykiss; 8.26 ± 1.10 g). A total of eight dietary treatments were evaluated: control with garlic powder (0 MBM+G), 250 MBM+G, 450 MBM+G, and 650 MBM+G (g MBM/kg diet; treatments with garlic powder; G treatments), control without garlic powder (0 MBM), 250 MBM, 450 MBM and 650 MBM (g MBM/kg diet; treatments without garlic powder; WG treatments). Our results demonstrated that increased dietary content of MBM impaired growth and production performance, body composition, digestive enzyme activity, tissue fatty acid profile and overall digestibility. Addition of garlic powder was able to correct fish performance, body composition, enzyme activity and digestibility to some extent. Dietary supply of garlic resulted in increased digestive enzyme activity improving fish performance. The current results indicated that fish fed 650 g MBM/kg feed exhibited impaired growth that could be attributed to reduce digestibility of protein, fat, energy and dry matter, PUFAs and n-3 LC-PUFAs in muscle. We suggest that 450 g FM per kilo feed can be successfully replaced with MBM supplemented with 30 g garlic powder per kilo feed without impairing fish performance and physiology, however distorting tissue fatty acid composition resulting in lesser levels of n-3 LC-PUFAs compared to the 0 MBM+G diet.

Effects of Pawpaw Seed Powder as an Additive on Growth of Catfish Fingerlings Reared in an Indoor Tanks

Since the demand of African Catfish (Clarias gariepinus) is on increase there is need to increase its production so as to meet the protein requirement of the populace. An investigation was conducted for six weeks feeding trial to determine the performance of African catfish (Clarias gariepinus) fingerlings feed diets containing varying replacement level of fish meal with pawpaw seed powder meal (Carica papaya). Fingerlings of Clarias gariepinus were subjected to five different dietary treatments with varying levels of pawpaw seed powder meal. The diets I-V contained 0, 20%, 40%, 60% and 80% replacement levels, respectively. The experiment was carried out in an 80 litres circular plastic bowls, the treatments were in triplicate. Each bowl contained 12 fingerlings. Feeding was done at 3% body weight per day and fishes were weighed every week. Growth parameters such as specific growth rate (SGR), weight gained (WG), food conversion ratio (FCR), protein efficiency ratio (PER) and mortality were determined. Therefore, it could be concluded that fish meal could be replaced up to 80% with pawpaw seed powder meal in the diet of Clarias gariepinus fingerlings to encourage growth, while at 40% pawpaw seed powder meal inclusion mortality was reduced.

Effect of fishmeal and fish oil replacement by vegetable meals and oils on gut health of European sea bass (Dicentrarchus labrax)

The main objective of this study was to assess the effects of graded levels of replacement of fishmeal (FM) and fish oil (FO) by terrestrial meals (TM) and vegetable oils (VO) on gut health of European sea bass (Dicentrarchus labrax) based on gut morphology, gut-associated immune system (GALT) and gut microbiota composition. Reducing the dietary FM and FO levels down to 10 and 3%, respectively did not affect the growth of European sea bass. Increase in TM and VO markedly affected anterior and posterior gut morphology and fatty acid composition, which mirrored the dietary fatty acid profile. FO replacement by VO increased lipid deposition in anterior gut lamina propria, denoting an effect in lipid metabolism and lipoprotein synthesis. In posterior gut, FM replacements by TM induced an engrossment of the submucosa, an up-regulation of the proinflammatory cytokines IL-1β and TNFα genes, a relatively high mucus production and changes in mucosal microbiota profiles. Finally, supplementation of 0%FM-0%FO diets with LC-PUFA contributed to maintain gut homeostasis in terms of GALT response and microbiota profiles alterations. Statement of relevanceFM and FO appropriate dietary levels for European seabass

Partial replacement of fish-meal by soy protein concentrate and soybean meal based protein blend for juvenile Pacific white shrimp, Litopenaeus vannamei

An 8-week feeding trial was conducted to evaluate the effect of fish-meal replacement on growth performance, whole body composition, apparent digestibility coefficients and anti-oxidative ability of juvenile Pacific white shrimp, Litopenaeus vannamei. Five practical diets were formulated to contain graded levels (5, 10, 15, 20 and 25%) of fish-meal. Soy protein concentrate and soybean meal based protein blend was used to replace fish-meal, amino acids were supplemented in the low fish-meal diet to get similar amino acid profile as the high fish-meal diet. Weight gain, survival, feed conversion rate (FCR), feed intake and protein efficiency ratio (PER) did not show any significant differences between any of the groups. Alanine ratio in whole body were higher in shrimp fed high fish-meal diets while arginine decreased with the increasing fish-meal levels. The Fe content in whole body was significantly lower in shrimp fed the low fish-meal diets, while the other minerals showed no difference among all the groups. Apparent digestibility coefficients (ADC) of dry matter, protein, Ca, P, Cu, Zn and Mg were equal in all the treatments, while ADC of Fe decreased with the decreasing fish-meal levels. When dietary fish-meal decreased, the anti-oxidant related enzymes activity (Total antioxidant capacity (T-AOC) and Catalase (CAT)). Superoxide dismutase (SOD) was unaffected by treatments. Nitric oxide (NO) contents in hemolymph significantly decreased with the decreasing fish-meal levels, while Phenoloxidase (PO) was unaffected. The results indicated that growth performance and apparent digestibility coefficients of nutrients were not affected when fish-meal was replaced from 25% to 5%, but anti-oxidative ability and immune response were damaged after fish-meal level decreased to 15%. Statement of relevanceThe results of this manuscript contribute to the commercial feed industry of white shrimp, it will be helpful in fish meal replacement, which is very important to the sustainable development of aquaculture.

Optimization of fishmeal, fish oil and wheat in diets for juvenile sablefish,Anoplopoma fimbria

Sablefish Anoplopoma fimbria is a piscivorous fish that is highly desirable as food. To ascertain the relationship of dietary protein, lipid and carbohydrate, eleven diets containing fishmeal, fish oil and wheat flour as test ingredients at different levels were formulated. The levels were chosen according to mixture experiment methodology, which varies the proportion of each test ingredient, while keeping their sum constant across all diets. The range of levels used in the test diets were as follows: fishmeal 430–600 g kg−1, fish oil 100–270 g kg−1 and wheat flour 30–200 g kg−1. The sum of the test ingredients accounted for 900 g kg−1 of all diets, with the remaining 100 g kg−1 accounting for mineral and vitamin premix, binders, attractant, etc. Each diet, plus a commercial feed, was fed to three tanks of juvenile sablefish by hand twice daily for 11 weeks, using a completely random design. It was found that growth and feed efficiency were maximized by the highest dietary inclusion level of fish oil and fishmeal, corresponding to the lowest wheat flour level, that is 600 g kg−1 fishmeal, 270 g kg−1 fish oil and 30 g kg−1 wheat flour.

Weaning wild flathead grey mullet (Mugil cephalus) fry with diets with different levels of fish meal substitution

The culture of flathead grey mullet (Mugil cephalus) is based on wild fry captured during their migration into estuarine environments and consequently, optimizing weaning diets is of special importance for this species at this particular stage of development. Thus, authors have tested a weaning protocol for wild flathead grey mullet fry (202mg initial body weight) during 60days (18.1±0.3°C, salinity, 1.2±0.2‰) using compound diets (36% crude protein, 16% crude fat) with different levels of fish meal (FM) substitution by plant protein (PP) sources (50% and 75% of FM replacement by a blend of corn gluten, wheat gluten, soy bean meal and soy protein concentrate). Fry were progressively weaned onto experimental diets during the first 20days of the trial (25% Artemia metanauplii replacement each 5days), whereas compound diets were offered at a feed ratio of 5% of stocked biomass until the end of the trial (day 60). A blend of PP sources (corn gluten, wheat gluten and soy protein concentrate) as the main dietary protein sources in combination with crystalline l-lysine and dl-methionine dietary supplementation were as good as a FM-based diet in terms of growth performance, digestive physiology and fish condition (i.e. proximate composition, oxidative stress status). As the cost-benefit proxy analysis of the tested weaning diets indicated, the inclusion of alternative PP was a satisfactory strategy in terms of feed price reduction, since PP50 and PP75 diets were 15.5 and 23.6% cheaper than the FM diet. Although wild flathead grey mullet fry were satisfactorily weaned onto diets containing 75% FM substitution by PP sources, present results indicated that complete FM replacement in weaning diets for this species might also be feasible. Statement of relevanceIn this study, authors have tested a weaning protocol for wild flathead grey mullet (Mugil cephalus) fry based on diets with different levels of fish meal substitution by alternative plant protein sources. This is of special importance due to the importance of the aquaculture of this species in several regions of the word, as well as for the use of wild animals for on-growing purposes. Results showed that diets with 75% of fish meal substitution can be successfully used for weaning and on-growing wild fry without any detrimental effect of fry performance and condition.

Supplementations of poultry by-product meal and selenium yeast increase fish meal replacement by soybean meal in golden pompano (Trachinotus ovatus ) diet

The effects of poultry by-product meal (PBM) and selenium yeast (Se-yeast) supplementations on fish meal replacement by soybean meal (SBM) in the diet of golden pompano (Trachinotus ovatus) were examined. In trial I, a 2 × 3 layout including two PBM levels (100 and 170 g kg−1) and three levels of fish meal replacement (0, 40 or 60%) was used. At 100 g kg−1 PBM, fish fed the basal diet exhibited the highest weight gain (WG) and nitrogen retention efficiency (NRE) and the lowest feed conversion ratio (FCR). At 170 g kg−1 PBM, no significant differences were found in WG and NRE between fish fed the basal diet and diet with 40% of fish meal replaced by SBM. In trial II, the basal diet containing 170 g kg−1 PBM (trial I) served as a reference. A 2 × 2 layout included two levels of fish meal replacement (40 or 60%) and two levels of Se-yeast addition (0 and 1 g kg−1). No significant differences were found in WG, feed intake, FCR and NRE between fish fed the reference diet and diet with 40 or 60% fish meal replacement plus 1 g kg−1 Se-yeast addition. This study indicates that supplementations of PBM and Se-yeast can enhance the level of fish meal replacement by SBM in golden pompano diet. Dietary fish meal level can be reduced to 140 g kg−1 by optimizing inclusion of SBM, PBM and Se-yeast.

Effects of β-xylanase and 6-phytase on digestibility, trace mineral utilisation and growth in juvenile red tilapia,Oreochromis niloticus(Linnaeus, 1758)x O. mossambicus(Peters, 1852), fed declining fishmeal diets

Summary In response to the global sustainability drive to lower fishmeal (FM) inclusion in aquatic feeds, exogenous enzymes can improve nutrient digestibility in monogastric plant-based diets. A 80-day experiment was conducted to evaluate the combined effects of xylanase and phytase on digestibility, trace mineral utilisation and growth in juvenile red tilapia, Oreochromis niloticus x O. mossambicus, (48.8 g ± 13.9; μ ± STD) fed declining FM diets. Basal diets were formulated to contain 0, 3 and 5% FM with and without xylanase (0.385 g kg−1) and phytase (0.075 g kg−1), forming six treatments. Each treatment was randomly assigned to four replicates, 20 fish tank−1; mean water temperature 28.98 ± 0.73°C. Although the size of the effects was modest, growth performances (feed intake, FCR, growth rate) decreased with lower FM levels (P < 0.05) but improved with enzyme supplementation. Enzyme supplementation increased P digestibility and trace mineral uptake (P < 0.05), but no effects were seen on protein digestibility and N retention. Nevertheless, tilapia fed the enzyme-supplemented 3% FM and control 5% FM diets performed comparably (P < 0.05). This potentially justifies a 2% FM reduction for tilapia diets using exogenous xylanase and phytase without significant effects on digestibility, trace mineral utilisation and growth.

Pengaruh Pemberian Tepung Ikan Lemuru (Sardenella Fimbriata) Terhadap Persentase Karkas Broiler

ABSTRACT. An experiment was conducted for five weeks to study the effect on feeding different levels of fish meal, Sarninella fibriata on carcass percentage of Cobb broiler strain. 120 day old Cobb chicks were randomly divided into eight expremiental groups, each consisting of 15 birds. Each groubs of 15 bird was divided into three replications of five birs, which then placed into 1x1 x 0.7 m cages at the rate of five birds per cage. Group one, two, three and four were fed 1 %, 4%, 7% and 10% of fish meal, Sardinella fibriata. Groub five, six, seven and eight were maintained with feed and water always available. The carcass percentage of teo birds of each five bird of each reflication were recorded at the end of the experiment. The average of carcass pecentage of groub one, two, three and four of fish meal. Sardinella fimbriata were 62, 67, 69, 68.40 and 69.37% resvectivaly. The average of carcass percentage of groub five, six, seven and eight of commercial fish meal were 63.22, 59.49, 64.90 and 70.22% respectively. There were significant different (P0.01) between groub six and groub eight of commercial fish meal, but there were no significant differences noted.

Effect of Taurine Supplementation on Growth Response and Body Composition of Largemouth Bass

AbstractTaurine is “conditionally essential” for some fish species, particularly when fish meal levels in their diets are reduced. Taurine supplementation has not yet been evaluated in the Largemouth Bass Micropterus salmoides. A 12‐week feeding trial was conducted using a 2 × 2 factorial design with the main effects being fish meal inclusion (0% or 30%) or taurine supplementation (0% or 2%). The fish meal diets contained sardine fish meal while the nonfish meal diets used pork meal, which has a very low taurine content, as the animal source protein. The four experimental diets were formulated to contain 40% crude protein and 12% lipid. The feeding trial was conducted using juvenile Largemouth Bass (19.3 ± 3.9 g; mean ± SD) stocked at 25 fish/tank into twelve 230‐L aquaria within a recirculating system. Fish were fed to apparent satiation twice daily. Dissolved oxygen, pH, and temperature were monitored daily, while alkalinity, total ammonia nitrogen, and nitrite‐nitrogen were monitored three times weekly. Analysis of harvest data indicated a significant statistical interaction between fish meal inclusion and taurine supplementation only for feed conversion ratio (FCR). In diets containing no fish meal, the addition of taurine significantly increased the FCR (from 2.2 to 2.6). However, in fish fed diets containing fish meal, supplemental taurine significantly decreased the FCR (from 2.2 to 1.9). In terms of main effects, taurine supplementation did not significantly affect any of the measured growth or survival variables. Survival and growth in Largemouth Bass fed 0% fish meal were not significantly different from survival and growth in those fed 30% fish meal. Body composition variables were not significantly affected by either fish meal inclusion or taurine supplementation. These data support previous studies that found that by‐products from terrestrial animal sources can successfully replace fish meal in diets for Largemouth Bass. These data also indicate that Largemouth Bass do not have a significant dietary requirement for taurine.

Atlantic Salmon (Salmo salar L.) Gastrointestinal Microbial Community Dynamics in Relation to Digesta Properties and Diet.

To better understand salmon GI tract microbial community dynamics in relation to diet, a feeding trial was performed utilising diets with different proportions of fish meal, protein, lipid and energy levels. Salmon gut dysfunction has been associated with the occurrence of casts, or an empty hind gut. A categorical scoring system describing expressed digesta consistency was evaluated in relation to GI tract community structure. Faster growing fish generally had lower faecal scores while the diet cohorts showed minor differences in faecal score though the overall lowest scores were observed with a low protein, low energy diet. The GI tract bacterial communities were highly dynamic over time with the low protein, low energy diet associated with the most divergent community structure. This included transiently increased abundance of anaerobic (Bacteroidia and Clostridia) during January and February, and facultatively anaerobic (lactic acid bacteria) taxa from February onwards. The digesta had enriched populations of these groups in relation to faecal cast samples. The majority of samples (60-86 %) across all diet cohorts were eventually dominated by the genus Aliivibrio. The results suggest that an interaction between time of sampling and diet is most strongly related to community structure. Digesta categorization revealed microbes involved with metabolism of diet components change progressively over time and could be a useful system to assess feeding responses.

Effects of Partial Replacement of Fishmeal with Seaweed (&lt;i&gt;Lobophora variegata&lt;/i&gt;) Meal on the Growth and Biochemical Composition of Commercial Important Fish Asian Seabass&lt;i&gt; Lates calcarifer&lt;/i&gt; (Bloch, 1790) Fingerlings

Seaweeds are large algae (macro algae) that grow in a brackishwater or marine environment. They are a valuable food source and contain significant quantities of proteins, lipids, vitamins and minerals. Algae meals are alternative plant feedstuffs that are increasingly being used in aqua feeds because of their nutritional quality, lower cost and availability. This study is an attempt made on the effects of replacing fish meal with the brown seaweed ( Lobophora variegata ) on the growth and biochemical composition (protein, lipids, carbohydrates) of Asian seabass Lates calcarifer fingerlings. Investigations on the biochemical constituents and nutritive profile of the formulated feeds showed that seaweeds could be the better replacement for fish meal in pelleted feeds. The seaweeds used in our study did not seem to affect the palatability of the diet for this carnivorous fish. Therefore, reducing fishmeal inclusion levels and replacing fishmeal with cost-effective, widely available and sustainable feedstuffs are considered essential for the future development of the aquaculture industry.

Lasting effects of butyrate and low FM/FO diets on growth performance, blood haematology/biochemistry and molecular growth-related markers in gilthead sea bream (Sparus aurata)

Four isoproteic/isolipidic plant protein-based diets were formulated to assess the lasting effects of feed additives and low fish meal (FM) and fish oil (FO) diet formulations on gilthead sea bream growth performance. FM was included at 23% in the control diet (D1) and at 3% in the other three diets (D2, D3, D4). Added oil was either FO (D1) or a blend of vegetable oils replacing 58% (D2) and 84% (D3, D4 diets) of FO. A commercial sodium butyrate preparation (NOREL, 70-BP) was added to the D4 diet at 0.4%. Each diet was allocated to triplicate groups of juvenile fish fed to satiety over an 8-month feeding trial (May–December). All fish grew efficiently from 15g of initial body weight to 296–320g with an overall feed efficiency (FE) of 0.95–1.01, although fish fed D3 and D4 diets showed transient growth impairments over the course of the first four weeks of the trial. Data on biometric indexes, whole body composition, haematology and blood biochemistry revealed a strong effect of sampling time in fish sampled at mid-summer (August) and late autumn (December). In contrast, the diet effect was mostly reduced to a few blood parameters. Low inclusion levels of FM reduced plasma haemoglobin levels (D2, D3), but these effects were reversed by butyrate supplementation (D4). The same phenomena occurred for total cholesterol with the highest circulating concentration of choline and IGF-I in fish fed the D4 diet during their summer growth spurt. At the transcriptional level, gene expression profiling of liver and skeletal muscle with a PCR-array of 87 growth markers provided additional evidence for an overall well-growth condition in all of the experimental groups. Up to 73 genes were found at detectable levels in the liver tissue, but only 13 were differentially expressed. Likewise, 84 genes were actively transcribed in the skeletal muscle, but only nine were differentially expressed in at least one experimental group. Butyrate supplementation reversed the up-regulated expression of inflammatory cytokines (TNFα) and muscle markers of cellular morphogenesis and protein breakdown (CDH15, CAPN3, PSMA5, PSMB1, UBE2N) in the muscle of fish fed the extreme D3 diet. These results support the use of low FM/FO diets alone or supplemented with feed additives, which have the potential to improve or reverse metabolic steady-states. Statement of relevanceButyrate effect on low fish meal/fish oil diets.

Air-classified faba bean protein concentrate is efficiently utilized as a dietary protein source by post-smolt Atlantic salmon (Salmo salar)

High-quality sources of protein for the formulation of feeds of carnivorous fish species such as Atlantic salmon are currently being sought. In an earlier screening trial we evaluated for the first time in Atlantic salmon (Salmo salar) the applicability of air-classified faba bean (Vicia faba) protein concentrate (BPC) inclusions in combination with soy protein concentrate (SPC) and fishmeal (FM) using parr as a model. Based on the results in parr in freshwater, the present study tested the hypothesis that BPC can effectively replace SPC and/or FM as a dietary protein source in post-smolt Atlantic salmon in seawater. The trial was designed to test nine different combinations of BPC, SPC and FM around the ideal mixture proportions modelled from data on parr (20% BPC, 46% SPC and 34% FM as percent of the total dietary protein). Somatic, physiological, biochemical and molecular parameters were assessed to determine fish performance. On average, fish grew from ~1.28kg to 2.80kg over the course of the 17week trial. Results demonstrated that a mixture of BPC, SPC and FM (208gkg−1, 193gkg−1 and 85gkg−1, respectively) resulted in the highest weight gain of post-smolts without significantly altering the FCR. Specifically, fish fed the highest inclusion of BPC and lowest level of FM had final weights on average 0.24kg more than those with the lowest inclusion of BPC and highest FM. Improved weight gain was not achieved at the expense of poorer FCR, which was lower in fish fed diets with higher content of BPC and lower FM. The highest level of inclusion of BPC tested herein (~21% of feed) could replace up to 8.5% FM (from 17% to 8.5% of feed) and 10% SPC (from 29% to 19% of feed), resulting in the largest improvement in weight gain. There were no biologically significant or physiologically important effects on nutrient digestibility, enteritis scores or hepatic gene expression of dietary BPC. Statement of relevanceThis study is highly relevant to the industry of feed manufacture.

An evaluation of the complete replacement of both fishmeal and fish oil in diets for juvenile Asian seabass, Lates calcarifer

An experiment was conducted to examine the potential for the complete replacement of fishmeal (FM) and fish oil (FO) in diets for barramundi, Lates calcarifer. A series of diets were formulated to the same digestible protein and energy specifications, but which were designed with FM inclusion levels at 300, 200, 100 or 0g/kg and FO at 100%, 30%, 15% or 0% of the added oil in the diets (4×4 factorial design). Ricebran oil was the alternative oil used in the growth study, while soybean meal and poultry meal were the main alternative protein sources used. For the growth study, fish of an initial weight of 154.4±1.1g were randomly allocated across 48 tanks (three replicates per treatment). After eight weeks, the average weight gain across all treatments was 187.7±2.3g/fish and feed conversion across all treatments averaged 1.04±0.01 feed/gain. A significant effect of FM on both feed intake and weight gain was observed, and this was observed as early as within the first few weeks, but no similar such effect was observed with FO. No effects were observed on protein deposition efficiency, though both lipid and energy deposition efficiencies were affected by FM level. The reduction in FO had a notable effect on the fatty acid composition of the diets and subsequently the fish fatty acid composition. Expression of key LC-PUFA metabolism genes in the liver of the fish was influenced by both FM and FO levels, but was only significant at the extremes of the treatment ranges. The results from this study demonstrate that there is clear potential to replace almost all the FM content of barramundi diets without loss of fish performance, up to and including diets with as little as 100g/kg fishmeal. Replacement of fish oil was more successful with the ability to completely replace all FO demonstrated at all but the lowest inclusion levels of FM. These results clearly demonstrate that the near complete replacement of both FM and FO in barramundi diets is a technical reality.

Effects of temperature and feed processing on protease activity and dietary protease on growths of white shrimp,Litopenaeus vannamei, and tilapia,Oreochromis niloticus × O. aureus

Effects of temperature and processing on the stability of a commercial protease were assessed in an in vitro trial followed by growth trials with white shrimp and tilapia. Results showed that the protease has a high heat stability against pelleting, and it could hydrolyse dietary proteins during feed processing. In Exp. 2, white shrimp (3.3 g) fed low fish meal (FM) diet (LFD) with protease addition had similar growth to that fed high fish meal diet, and both had higher weight gain (WG) and lower feed conversion ratio (FCR) than that fed LFD without protease addition (P < 0.05). In Exp. 3, compressed (CD) or extruded (ED) diets containing 30 g kg−1 or 90 g kg−1 FM were supplemented with or without protease and then fed to tilapia (1.7 g) for 8 weeks. WG was improved and FCR decreased (P < 0.05) by the supplementation of protease in 30 g kg−1 FMCD, but not in 90 g kg−1 FMCD and ED diets when compared to those diets without protease supplementation. The digestibility trial with CD indicated the improved apparent digestibilities of dry matter and crude protein by dietary protease in 30 g kg−1 FMCD, but not in 90 g kg−1 FMCD. Results above showed that the protease has a high heat stability and the supplementation of protease in CD with low FM level can improve the growth of shrimp and tilapia.