Fish meal quality assessment for Atlantic salmon (Salmo salar L.) reared in sea water

Studies were conducted to investigate the quality of 16 fish meals for Atlantic salmon ( Salmo salar L.) reared in sea water, and to assess in vitro and in vivo methods for the measurement of the quality of the protein in fish meals. The commercial fish meals tested were Canadian-produced (herring, groundfish, and mixed meals) and were of West Coast and East Coast origin; they included silver hake (Russian origin), two mackerel meals (Chilean) and Norwegian fish meal (Norse-LT94®). In addition, five herring meals were produced in the laboratory to assess the influence of processing conditions and freshness of the raw material on fish meal quality. The dilute-pepsin digestibility was the preferred in vitro assay to evaluate the protein quality of herring meals for Atlantic salmon, but this assay correlated poorly with the results from in vivo assays when other types of fish meals (menhaden, mackerel, silver hake, groundfish) were included.     

Chemical Characterization of Testes Meals Made from Alaska's Seafood Processing Byproducts

ABSTRACT

Our objective was to produce a unique feed ingredient from underutilized walleye pollock (Theragra chalcogramma) and pink salmon (Oncorhynchus gorbuscha) testes. Protein content in meals from both species (72% and 80%, respectively) were above the values found in high quality herring meals (～70%), but both were poor in some essential amino acids, e.g., methionine. Additionally, both were good sources of the amino acid taurine (1.7 and 2.2% of meal, respectively). Pollock meal was very rich in phospholipids (82% of total lipids) and in DHA (28 mg/g meal) and EPA (18 mg/g meal), indicating potential as an ingredient in larval starter diets. The purine contents in both pollock and salmon testes meals were more than 10 times the concentrations found in other fish byproducts or commercial fishmeals. The high concentrations of purines found in these testes, especially in the salmon meal, make it an ideal candidate for an immune system stimulant when added to dietary formulations.     

Marine and freshwater crab meals in diets for red porgy (Pagrus pagrus): effect on growth,fish composition and skin colour

River crab (RC) meal (Procambarus clarkii) and marine crab (MC) meal (Chaceon affinis) were tested as a partial replacement for fish meal in diets for red porgy (Pagrus pagrus), and their effects on growth performance, fish proximate composition and skin colouration were evaluated. Red porgy were fed during 165 days with five diets. High‐quality fish meal diet was used as a control diet (CD). Protein of fish meal in the control was replaced by increasing the dietary levels of protein derived from RC and MC by up to 10% and 20% of each of them (RC10, RC20, MC10 and MC20). Fish fed on MC20 showed the highest values in feed intake, weight gain and growth (%). No differences were found in FCR and protein efficiency ratio among the treatments. Inclusion of both crab meals in diets significantly decreased the lipid content in whole fish compared with the control animals. On the other hand, no differences in muscle composition were found between the diets. Feeding both crab meals resulted in colour improvement compared with that of the control fish, with better hue values for the RC meal group than those for the MC meal group. The crab meals tested in the present study are suitable as a partial replacement for fish meal in diets for the red porgy, with the MC meal improving growth and both crabs meals improving skin colour, with further improvements in skin colour produced in fish‐fed diets containing the RC meal.     

Fisheries by-catch and processing waste meals as ingredients in diets for Nile tilapia, Oreochromis niloticus

Digestibility, feeding and growth studies were conducted with Nile tilapia using diets containing fishery by‐catch and processing waste meals. Three meals manufactured from sorted fisheries by‐catch (MBM, from mixed benthic species, SPM, from small pelagic species, CAM, from mixed catfish species) one from tuna cannery waste (TCW) and one commercial anchovy meal (COM) were tested. By‐catch and processing waste meals had lower protein, lower lipid and higher ash contents than anchovy meal. The meals were all highly digestible and no significant differences (P≥0.05) were observed between apparent protein digestibility measurements. Five feeds, containing fish meal as the major protein ingredient, were formulated and fed to triplicate groups of 30 juvenile tilapias for 9 weeks. Survival, weight gain, specific growth rate (SGR), feed conversion ratio, protein efficiency ratio, phosphorus retention and whole body proximate composition were compared. Weight gain and SGRs were similar for each treatment group and compared favourably with the results obtained from juvenile tilapia elsewhere. Growth was the highest for CAM (P≤0.05), which contained both the highest essential amino acid levels and the highest ash content. Phosphorus retention was significantly lower in fish fed with high ash meals, MBM, CAM and TCW (P≤0.05) than in fish fed with the lower ash meals COM and SPM. Overall, the fisheries by‐catch and processing waste meals evaluated in this study are suitable protein ingredients for juvenile tilapia feeds.     

A comparison of the digestibility of lupin (Lupinus sp.) kernel meals as dietary protein resources when fed to either, rainbow trout, Oncorhynchus mykiss or red seabream, Pagrus auratus

The nutritional value of the kernel meals of three species of lupin (Lupinus albus, L. angustifolius and L. luteus) was compared against each other and solvent extracted soya bean meal and wheat gluten, when fed to either rainbow trout or red seabream. The digestible nutrient and energy values were determined for each ingredient, based on the diet substitution digestibility method. Each test ingredient was included in test diets at 300 g kg^?1. As different faecal collection methods were used on each species, only ingredient comparisons within each fish species study are valid. Protein digestibility for all lupin kernel meals was significantly better than for soya bean meal when fed to red seabream, although only numerically so when fed to rainbow trout. The highest protein digestibility in both fish species was that from the wheat gluten (100.0% for both rainbow trout and red seabream). Energy digestibility for each of the lupin kernel meals (range 62.4%–64.9% in rainbow trout and 60.9%–69.5% in red seabream) was less than that obtained from soya bean meal (75.1% and 81.0% for rainbow trout and red seabream, respectively). However, the higher gross energy content of the lupin kernel meals still resulted in both L. albus and L. luteus providing equivalent levels of digestible energy as that of soya bean meal. Organic matter digestibility was generally poorer for each of the lupin kernel meals relative to that for the soya bean meal and particularly compared with the wheat gluten. Phosphorus digestibility was significantly better in all lupin kernel meals than that from both the soya bean meal and wheat gluten. Highest phosphorus digestibility was that obtained from L. albus kernel meal (100.0% for both rainbow trout and red seabream) although notably the phosphorus digestibility of all lupin kernel meals when fed to rainbow trout was determined at 100%. Similarly the digestibility of phosphorus from lupin kernel meals fed to red seabream was also very high. This study supported the good nutritional value to both rainbow trout and red seabream of kernel meals of all three species of lupin, although the digestible nutrient attributes of kernel meal from L. luteus were particularly favourable.     

Element concentrations in meals from krill and amphipods, — Possible alternative protein sources in complete diets for farmed fish

In the marine environment, organisms from lower trophic levels seem as a good alternative to the traditional meal and oil sources. In the present study, meals were produced from Antarctic krill (Euphausia superba), Arctic krill (Thysanoessa inermis) and the Arctic amphipod Themisto libellula. Diets were then prepared for Atlantic salmon and Atlantic cod where up to 100% of the fish meal protein was replaced by protein from these organisms. Concentrations of copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) were determined by ICP-MS in the various krill and amphipod meals, complete diets and muscle samples from fish fed these diets. The element concentrations were related to growth and general fish health as well as present EU legislations on feed ingredients and complete diets. The cod showed no difference in growth during the trial, while salmon fed diets where 40% of the fish meal protein was replaced with Arctic krill or amphipod meal shoved improved SGR during the first period of feeding (first 100 days). No adverse effects on growth rate or fish health were observed in any fish species or treatment. Nevertheless, high levels of Cu were found in the meal from Antarctic krill (46 mg kg^− 1 dry matter (dm)) resulting in a dietary level of Cu exceeding the upper limit for complete feedingstuff set by EU. Furthermore, the Cd level found in the meal from amphipod (12 mg kg^− 1 dm) was 6 times higher than EU's upper limit. This indicates limitations for the use of certain zooplanktons as alternative protein sources in feed for farmed fish, unless future processing methods yield lower levels of these unwanted elements.     

An Evaluation of the Suitability of Selected Waste Products in Feeds for Three Fish Species

ABSTRACT

Five types of aquatic food industry waste products (carp offal, carp roe, fish frames, trout offal and surimi processing waste) together with fish meal were evaluated for their suitability as potential fish meal replacements, partially or wholly, in diets for three species (rainbow trout, Murray cod and shortfin eel) cultured in Australia, using a number of criteria.

The proximate composition of the ingredients on a dry matter basis including protein content, lipid and ash, varied considerably. The essential amino acid (EAA) contents of the waste products and fish meal decreased in the order: carp roe > fish meal > carp offal > ‘surimi’ processing waste > fish frames > trout offal. The results of cluster analysis of A/E ratios of waste products and fish whole body fell within three clusters. The EAAI of whole body tissue of Murray cod, rainbow trout and Australian shortfin eel however, were closest to fish meal, followed by fish frame waste and/or ‘surimi’ waste. The results on A/E ratios and EAAI did not conform to the raw data on TAA and EAA. Therefore, the study emphasizes the need to have a multi-prong approach to determine the suitability of ingredients for incorporation into fish feeds.     

Growth Rate of Pacu,Piaractus mesopotamicus,Fingerlings Fed Diets Containing Co-Dried Fish Silage as Replacement of Fish Meal

Abstract

Fish meal has been the most common animal protein source used to feed fish, even though it is fairly expensive and seasonally available. The objective of this work was to investigate co-dried fish silage as an alternative animal protein source for diets of pacu, Piaractus mesopotamicus.The diets did not differ significantly (P >0.05) with respect to average weight gain, ration consumption, apparent feed conversion, protein efficiency and specific growth rates. However, apparent protein digestibility and protein productive values were significantly different (P <0.01). Diets containing fish silage, co-dried with agricultural by-products (soybean meal or broken rice), showed better results than the control diet, which contained fish meal as the only animal protein source. The results showed that alternative ingredients can be used effectively to replace fish meal in pacu diets. Co-dried silages are economically and environmentally advantageous, since they use residues generated in the farm.     

Effect of partial and total replacement of fish, shrimp head, and soybean meals with red crab meal Pleuroncodes planipes (Stimpson) on growth of white shrimp Litopenaeus vannamei (Boone)

Red crab meal (RCM), as a potential protein source in diets for juvenile shrimp Litopenaeus vannamei, was evaluated over a 45‐day growth trial under laboratory conditions. Eight experimental diets were tested. The basal diet contained fish (tuna by‐product), shrimp head and soybean (solvent extracted) meals as primary protein sources. Fish or soybean meals were substituted, on an equal‐protein basis, at 33%, 66% and 100% by RCM, whereas shrimp head meal (SHM) was substituted at 100%. A commercial diet was included as a reference. Final weight ranged between 2.23 and 3.36 g and growth rates (GRs) between 0.048 and 0.073 g day⁻¹. Where 66% or 100% of the protein from fish or soybean meals was substituted by RCM, the diets produced significantly higher final weights and GRs than other diets. Regression analysis showed that final weight of shrimp depended significantly on the percentage of substitution, and that the maximum weight gain would be obtained when substituting RCM for 80.2% of fish meal and 81.2% of soybean meal. Feed conversion ratio was below 1.8 for all treatments and there was no apparent relationship with other aspects of the diet. Red crab meal served as a suitable protein source for partial or total replacement of tuna by‐product, soybean and SHMs for cultivated juvenile shrimp L. vannamei.     

Effects of Dietary Energy Level and Number of Meals on Growth and Body Composition of Nile Tilapia Oreochromis niloticus (L.) During Summer and Winter Seasons

Two feeding trials (experiments 1 and 2) were conducted to determine the combined effect of dietary energy levels (low energy, LE and high energy, HE) and number of daily meals (one meal with the entire daily amount, two meals with half of the daily amount, and three meals with one‐third of the daily amount) on the growth and body composition of Nile tilapia Oreochromis niloticus in a recirculating system at different water temperatures, representing winter and summer seasons. In experiment 1 (winter), weight gain and specific growth rate (SGR) were significantly (P < 0.05) affected by dietary energy levels, but not by number of meals. Weight gain and SGR for fish fed the LE diet one daily meal were significantly (P < 0.05) higher than for fish fed the HE diet in one daily meal. Feed efficiency ratio (FER) and energy efficiency ratio (EER) were significantly (P < 0.05) affected by dietary energy levels, but not by number of meals. Protein efficiency ratio (PER) was not significantly (P > 0.05) affected by either dietary energy levels or number of meals. However, protein retention was significantly (P < 0.05) affected by both dietary energy levels and number of meals. The chemical composition (moisture, protein, lipid, and ash) of fish muscle was not significantly (P > 0.05) affected by either dietary energy levels or number of meals. However, visceral fat content was significantly (P < 0.05) affected by dietary energy levels, but not by number of meals. In experiment 2 (summer), weight gain and SGR were significantly (P < 0.05) affected by number of meals, but not by dietary energy levels. Weight gain and SGR for fish fed the LE and HE diets in two daily meals were significantly (P < 0.05) higher than those fed one daily meal. FER and PER were significantly (P < 0.05) affected by number of meals, but not by dietary energy levels. The highest FER and PER were observed in fish fed two daily meals. EER was significantly (P < 0.05) affected by both dietary energy levels and number of meals. Moisture and protein content of the whole fish were not significantly (P > 0.05) affected by either dietary energy levels or number of meals. Lipid content was significantly (P < 0.05) affected by dietary energy levels, but not by number of meals. Based on the results of these experiments, Nile tilapia should not be fed high‐energy diets to improve fish performance even under a limited feed allowance during winter or summer. Fish grew rapidly when fed two daily meals during summer, but number of meals had no effect on fish performance during winter.     

Comparison of the Nutritional Quality of Fish Meals Made from By-products of the Alaska Fishing Industry in Diets for Pacific Threadfin (Polydactylus sexfilis)

The nutritional quality of 13 commercial fish meals (10 from pollock, two from salmon, and one from cod) made from by-products of the Alaska fish processing industry was determined in diets for the marine fish Pacific threadfin Polydactylus sexfilis . Pelleted feeds were manufactured containing these meals as complete replacement of a low-temperature processed Norwegian fish meal (control). These feeds were fed to triplicate tanks of fish at the facilities of the Oceanic Institute, Hawaii for a period of 9 wk. At the end of the trial, the final weight, feed efficiency, protein efficiency ratio and survival data were subjected to ANOVA procedures. The performance parameters of the fish fed the white fish meals (pollock and cod) were not significantly different from the control. Of the two salmon meals, one promoted good growth and efficiency and one did not. It is concluded that the nutritional quality of Alaska white (pollock and cod) fish meals is equivalent to that of the low-temperature Norwegian fish meal and are of suitable quality for inclusion in commercial feeds for Pacific threadfin.     

Effects of Feeding Rate and Feeding Frequency on Survival, Growth, and Body Composition of Ayu Post-Larvae Plecoglossus altivelis

The effects of feeding rate and feeding frequency on survival, growth and body composition of ayu post‐larvae (0.15 g in body weight and 3.5 cm in total length) were investigated in this study. A factorial experimental design of two feeding rates (3 and 6% of body weight of fish per meal) five feeding frequencies (one meal in 2 d, one meal a day, two meals a day, four meals a day, and six meals a day) with three replicates was used. Survival of ayu post‐larvae was significantly (P 0.05) affected by feeding frequency but not by feeding rate. Survival of ayu improved linearly with feeding frequency at both feeding rates. Weight and length gains and specific growth rate (SGR) of ayu was significantly (P 0.05) affected by feeding frequency but not by feeding rate, with weight and length gains and SGR linearly elevated with increasing feeding frequency at both feeding rates. The greatest weight and length gains were observed in fish receiving six meals daily at both feeding rates; however, no significant difference in weight gain was observed among two, four, and six meals a day, or in length gain between four and six meals a day. Feed efficiency ratio (FER) was significantly (P 0.05) affected by both feeding rate and feeding frequency. FER linearly decreased with feeding frequency at both feeding rates or feeding rate in the same feeding frequency. When the total daily amount of feed supply was constant with various feeding frequencies at different feeding rates (one meal a day at 3% feeding rate and one meal in 2 d at 6% feeding rate, two meals a day at 3% feeding rate and one meal a day at 6% feeding rate, or four meals a day at 3% feeding rate and two meals a day at 6% feeding rate), improvement in survival, weight and length gains, and SGR was observed in fish with higher feeding frequency at lower feeding rate. Moisture, protein, and lipid content of fish were not significantly (P > 0.05) affected by either feeding rate or feeding frequency. However, lipid content of ayu linearly increased with feeding frequency at 6% feeding rate. The highest body lipid content was observed in fish receiving six meals daily at both feeding rates. Ash content of fish was significantly (P 0.05) affected by feeding frequency but not by feeding rate. Based on performance of ayu, it can be concluded that optimum feeding rate and feeding frequency for ayu post‐larvae (an initial weight of 0.15 g) were 3% per meal and four meals a day, respectively, under these experimental conditions.     

Apparent digestibility of Asian carp‐ and common carp‐derived fish meals in feeds for hybrid striped bass Morone saxatilis ♀ × M. chrysops ♂ and rainbow trout Oncorhynchus mykiss

Apparent digestibility coefficients (ADCs) of nutrients (crude protein, amino acids, crude lipid, fatty acids, and minerals) were determined for fish meals derived from menhaden, Asian carp (combination of silver and bighead carps), and common carp in feeds for hybrid striped bass and rainbow trout. Extruded test diets were formulated to contain a 70 : 30 mixture of reference diet and test ingredient with yttrium oxide (1 g kg^?1) serving as the inert marker. Diets were randomly assigned to triplicate tanks and fish were fed once per day at 2% body weight. Fecal samples were collected by manual stripping. The ADCs were calculated according to standard procedures. The composition and digestibility of Asian carp and common carp meals was broadly similar to menhaden meal. Protein digestibility ranged from 86.5% (Asian carp meal) to 93.1% (common carp meal). Lipid was highly digestible with ADCs >100% for all ingredients. Although the Asian carp meal was less digestible than the other two fish meals, it was still a highly digestible ingredient. Our data suggest that fish meals derived from Asian or common carp would be valuable feedstuffs in diets for hybrid striped bass, rainbow trout, and possibly other cultured fishes.     

Evaluation of full-fat and defatted maggot meals in the feeding of clariid catfish Clarias gariepinus fingerlings

The nutritional implication of processed maggot meals, hydrolysed, defatted, full‐fat, sun‐dried and oven‐dried, in the diets of Clarias gariepinus fingerlings were evaluated. The nutrient density, proximate composition, gross energy and mineral constituents of the maggot meals were determined. Five isonitrogenous and isocaloric diets were formulated to provide 40% crude protein in which fish meal in the reference diet was completely replaced by any of the following processed maggot meals: oven‐dried full‐fat (ODM), sun‐dried full‐fat (SDM), defatted oven‐dried (DODM) and defatted sun‐dried (DSDM) maggot meals respectively. Fish were fed ad libitum in triplicate treatments for 56 days in glass tanks. Biological evaluations of the fish were based on growth performance and nutrient utilization indices. The result of the nutrient composition analysis showed that processing methods of defattening and drying influenced the nutrient density of maggot meal, with crude protein content ranging between 43.30% and 46.70% for full‐fat sun‐dried and hydrolysed/defatted oven‐dried maggot meals respectively. The result showed that growth performance and nutrient utilization of fish fed DODM and DSDM dietary inclusions were not significantly different and similar to fish fed the fish meal‐based diet. However, fish fed the diet containing SDM exhibited lower daily weight gain, protein efficiency ratio and specific growth. Generally, fish performed better when fed diets containing defatted maggot meals than full‐fat maggot meal, and compared favourably with fish fed the fish meal‐based diet.     

Nutritional assessment of Australian canola meals. I. Evaluation of canola oil extraction method and meal processing conditions on the digestible value of canola meals fed to the red seabream (Pagrus auratus, Paulin)

This study assessed the nutrient and energy digestibility of a variety of canola protein products that were produced by processing canola meal under different conditions, using the red seabream, Pagrus auratus. The test canola protein products included solvent‐extracted canola meal, expeller‐extracted canola meal alone or subjected to one of two different heat treatments (120 or 150°C for 30 min), and expeller meal further processed to produce a canola protein concentrate (CPC). Solvent‐extracted soybean meal was also included in the study as a reference ingredient. Daily feed intake and blood thyroid hormone levels over the experimental period were also examined. The total digestible protein content of the expeller‐ and solvent‐extracted canola meals was 356 and 358 g per kg dry matter (g kg DM^?1) respectively. The total digestible energy content of the expeller‐ and solvent‐extracted canola meals was 14.23 and 8.60 MJ kg^?1 respectively. The organic matter digestibilities of the solvent‐extracted canola meal were poorer than noted for the expeller‐ and solvent‐extracted soybean meal. Notably, the two sources of canola meals used in this study (solvent and expeller meals) did not cause problems with declining feed intakes or changes to blood levels of thyroid hormones when included in the diets of the fish at a 30% level, and the diets were fed over a 3‐week period. The preparation of a CPC resulted in gains in total digestible energy, but a reduction in the amount of total digestible protein, relative to the expeller canola meal from which it was produced. However, the protein concentrating process marginally reduced the relative digestible value of the protein content. Heating expeller meal at 120 or 150°C for 30 min resulted in progressive reductions of all nutrient and energy digestibilities.     

Amino acids composition and protein quality evaluation of marine species and meals for feed formulations in cephalopods

The amino acid composition and protein levels of three species of cephalopods (Octopus vulgaris, Loligo gahi and Todarodes sagittatus), the natural diets of common octopus (O. vulgaris) and different kinds of meals were determined in order to optimise the content of these nutrients in artificial feeds. Arginine, leucine and lysine were the most abundant essential amino acids in cephalopods, while glutamate and aspartate represented the main non-essential amino acids. Arginine and leucine were the limiting amino acid in most samples, with maximum Chemical Score values for mussel (79–98 %), squid (84 %) and crustaceans (65–91 %); medium for fish (41–70 %); and minimum for meals (29–64 %). Mussel, squid, crustaceans and fish showed a high essential amino acid index according to Oser (OI: 88–99 %) suggesting a suitable amino acid balance. The protein from animal meals (fish and krill) covered all the essential amino acids except arginine and lysine in fish meal. The vegetable meal presented the worst amino acid balance (OI: 74–89 %) with several deficiencies in essential amino acids, including arginine, threonine, lysine and methionine. Supplementation with arginine or leucine and protein complementation of crustaceans and bivalves with fish or animal meal are proposed as alternatives for improving the performance of protein in feed for cephalopods.     

Digestibility of selected feedstuffs in subadult Caspian great sturgeon,Huso huso using settlement faecal collection and stripping methods

Apparent crude protein (ADC_CP), crude fat (ADC_CF) and gross energy (ADC_GE) digestibility coefficients of several typical and novel feedstuffs were determined to be employed in the formulated diets of subadult beluga (17.70 ± 0.234 kg) diets via two faecal collection methods of settlement (SFCM) and stripping (StM). The tested feedstuffs included three fish meals, three terrestrial animal by‐products, three plant protein concentrates, nine high‐protein plant meals and three low plant protein meals. ADC_CP values varied in different fish meals ranging from 89.5% for Mexican sardine meal to 93.2% for anchovy meal with SFCM. ADC_CP values for plant protein concentrates ranged from 82.8% for wheat gluten meal to 92% for soy protein with SFCM. ADC_CP ranged from 37.2% for whole wheat to 75.6% for spirulina meal with SFCM. ADC_GE was lower in low‐protein plant meals (64.1%) in comparison to high‐protein plant meals (70.2%). Fish meals showed the highest ADC_CF values. A significant (P < 0.05) quadratic regression relation (r² = 0.92) was observed among in vivo ADC_CP of five feedstuff classes fed to beluga and in vitro ADC_CP. The differences among ADC values appear to be significantly related to the effects of feedstuffs and therefore diet and faecal collection methods.     

Growth in Arctic charr and rainbow trout fed temporally concentrated or spaced daily meals

The effect on growth of distributing feed over a few hours compared tomore frequent meals was tested on 1+ Arctic charr (Salvelinus alpinus L.) and 1+ rainbow trout (Oncorhynchus mykiss Walbaum). Triplicate hatchery groups for each treatment were fed at a ration level of 1%/dayeither with few meals (8 times per day divided into morning and evening)or with frequent meals (32 meals equally distributed during the day). Wefound an opposite effect of meal frequency on growth in the two species.Low feeding intensity (8 meals per day) had a significantly positive effecton growth in rainbow trout but a significantly negative effect on growth inArctic charr when compared to feeding the fish frequent meals. Theopposite response to meal frequency is likely to be an effect of thedifferences in activity during feeding. Rainbow trout feed much moreaggressively than charr which can result in feeding being a more stressfulevent. In this experiment, the specific growth rate was lower and the feedconversion ratio higher for Arctic charr compared to rainbow trout.     

Effect of partial replacement of fish meal with soybean meal and feeding frequency on growth,feed utilization and body composition of juvenile Chinese sucker,Myxocyprinus asiaticus (Bleeker)

A factorial (2 × 4) feeding trial was conducted to investigate the effects of feeding frequency and partial replacement of fish meal (FM) with soybean meal (SBM) on the growth performance, feed utilization and body proximate composition of juvenile Chinese sucker. Two feed types including replacement of 30% FM (diet 1) with SBM (diet 2) were used. Triplicate groups of fish (average weight, 11.80 ± 0.19 g) were fed each feed type to visual satiation at four meals per day, three meals per day, two meals per day and one meal per day for 8 weeks. At the end of the feeding trial, the survival of fish was not significantly different among the treatments. Weight gain was affected by the feeding frequency. The highest weight gain was observed in fish fed with diet 1 at three meals per day. There existed a significant difference in daily feed intake (DFI), daily protein intake (DPI), feed conversion ratio (FCR) and protein efficiency ratio (PER) when the feeding frequency was increased from one or two to three or four meals per day (P < 0.001), but not by the feed types. For both two feed types, the highest DFI and DPI were observed at three meals per day. The highest PER was gained at four meals per day, while FCR was the least. The body proximate composition of fish was altered by feeding frequency. The crude lipid content increased with the increase in feeding frequency. Essential amino acids (EAAs) content showed no significant differences among different treatments. The present findings suggest that three feedings per day at visual satiation may be sufficient for the maximal growth performance of Chinese sucker grown from 11 to 45 g. Results also indicate that about 30% of FM protein can be replaced by SBM protein in Chinese sucker diets without adversely affecting growth.     

Effects of Feeding Diets with and without Fish Meal on Production of Channel Catfish,Ictalurus punctatus,Stocked at Varying Densities

ABSTRACT

Animal protein, generally fish meal, has traditionally been used in the diet of channel catfish. However, our previous research indicates that animal protein is not needed for growing stocker-size catfish to food fish when the fish are stocked at densities typical of those used in commercial catfish culture. Whether this holds when fish are stocked at high densities is not known; thus, we conducted an experiment to evaluate the effect of feeding diets with and without fish meal to channel catfish stocked in earthen ponds at different densities. Two 32% protein-practical diets containing 0% or 6% menhaden fish meal were compared for pond-raised channel catfish, Ictalurus punctatus, stocked at densities of 14,820, 29,640, or 44,460 fish/ha. Fingerling channel catfish with average initial weight of 48 g/fish were stocked into 30 0.04-ha ponds. Five ponds were randomly allotted for each fish meal level?×?stocking density combination. Fish were fed once daily to satiation for two growing seasons. There was a significant interaction between stocking density and fish meal for net production; net production increased in fish fed a diet containing fish meal compared with those fed an all-plant diet at the highest stocking density, but not at the two lower stocking densities. Net production of fish fed diets with and without fish meal increased as stocking density increased. Viewing the main effect means, weight gain decreased and feed conversion ratio increased for fish stocked at the two highest densities, and survival was significantly lower at the highest stocking density. Visceral fat decreased in fish at the two highest stocking densities. Body composition data were largely unaffected by experimental treatment except for a reduction in percentage filet fat in fish at the highest stocking density, and fish that were fed diets containing fish meal had a lower percentage fillet protein and a higher percentage fillet fat. It appears that at stocking densities two to three times higher than generally used, animal protein (fish meal) may be beneficial in the diet of channel catfish. In regard to stocking densities, high stocking results in higher overall production, but the average fish size decreased as stocking density increased.