Effect of replacing fish meal with soybean meal on growth, feed utilization and carcass composition of cuneate drum (Nibea miichthioides)

The effect of replacing fish meal with soybean meal (SBM) in practical feeds for cuneate drum was evaluated in an 8-week net pen trial. The cuneate drum fingerlings (initial body weight 29.8 ± 1.3 g fish^− 1) were fed six isonitrogenous and isocaloric feeds containing 39% digestible protein and 16 MJ kg^− 1 digestible energy. The control feed was formulated to contain 40% herring meal, whereas in the other five feeds SBM was included at 11.3, 22.5, 33.8, 45.0 and 56.3% to replace 20, 40, 60, 80 or 100% of the fish meal. There were no significant differences in feed intake between fish fed the control feed and feeds in which SBM replaced 20 to 80% of the fish meal, but fish fed the fish meal free feed had higher feed intake than the other treatments. Weight gain linearly declined with the decrease of fish meal level. Final body weight (FBW) of fish fed the feeds in which SBM replaced 20% of the fish meal did not significantly differ from fish fed the control feed. Replacing 40 to 100% of the fish meal resulted in lower FBW and nitrogen retention efficiency (NRE), and higher feed conversion ratio (FCR) than those of fish fed the control feed. Fish fed the feeds in which SBM replaced 60 to 100% of the fish meal had lower condition factor and hepatosomatic index than those of fish fed the control feed. No significant differences in carcass protein content was found among the treatments, but fish fed the feeds in which SBM replaced 60 to 100% of the fish meal had higher moisture and lower lipid content in carcass than those of fish fed the control feed. Results of the present study appear to indicate that cuneate drum has a limited ability to utilize SBM as a protein source in practical feeds.     

Effect of replacing soybean meal with yeast‐fermented canola meal on growth and nutrient retention of Nile tilapia,Oreochromis niloticus (Linnaeus 1758)

Yeast fermentation integrated with water soaking was applied as a method to reduce the levels of some anti‐nutritional factors in canola meal. The procedure completely eliminated glucosinolates and it reduced phytic acid content by 18%. It also led to increase of 9% of crude protein and 8–32% of some minerals in the meal. A 60‐day feeding trial was conducted to evaluate replacement of dietary soybean meal protein with yeast‐fermented canola meal for Nile tilapia at ratios of 0, 25, 50, 75 and 100% respectively. Three groups of fish with an initial weight of 10 g were fed with each diet twice a day to an apparent satiation. The results showed that there were non‐significant differences (P > 0.05) in growth, survival rate, feed intake and feed conversion ratio for all fish fed with the test diets. However, replacement with 75 and 100% levels significantly reduced (P < 0.05) protein efficiency ratio and nutrient digestibility of protein, lipid, ash, Ca, Mg and P of fish compared with the lower levels. The low retention of protein, lipid, ash, Ca, Mg and P were also observed. These effects seemed to be related to an increased dietary phytic acid.     

Evaluation of Methionine Supplements and Their Use in Grain‐based Feeds for Litopenaeus vannamei

The use of dietary supplements in commercial shrimp production feeds is increasing because of the need to reduce marine meal (e.g., fish meal) content. Our study evaluated leaching and apparent digestibility of artificial methionine supplements and their use in determining appropriate feeding levels of methionine in practical fish meal replacement diets fed to Litopenaeus vannamei. Three forms of methionine were evaluated: dl ‐methionine HCl, various mineral chelates of methionine, and a short‐chain synthetic methionine polymer. Results showed a significant increase (P < 0.05) in leaching loss of methionine from feeds with decreasing salinity and that leaching was significantly higher for dl ‐methionine than other forms in all salinity treatments. No significant difference was shown in apparent digestibility of methionine among digestibility diets, with the exception of diets supplemented with dl ‐methionine HCl. In two 6‐wk clear‐water growth trials, no significant difference in weight gain was shown by shrimp fed diets containing more than 0.4% methionine (1.14%, as percent of protein). This suggests that an appropriate feed level of methionine for practical plant protein‐based feeds is less than 0.4% of the diet. Results also indicated that mineral‐chelated and polymerized forms of methionine are appropriate for supplementation of plant protein‐based feeds.     

Phosphorus utilization in juvenile Clarias gariepinus fed phytase-supplemented diets based on soya bean (oil-extracted) and full-fat (roasted): A comparison

The effect of microbial phytase on phosphorus utilization in juvenile Clarias gariepinus (initial fish body weight 11.55 ± 0.2 g) was tested on two different diets based on oil-extracted soya bean (Experiment 1) and roasted soya bean meal (Experiment 2) using a 5 × 5 experimental design for 84 days. The basal isonitrogenous and isocaloric diets for oil-extracted and roasted soya bean were formulated to replace fish meal at 25% (S1E), 50% (S2E), 75% (S3E), 100% (S4E); and 25% (S1), 50% (S2), 75% (S3), 100% (S4), respectively. Each treatment was replicated four times. Microbial phytase was supplemented in each replicate at 250 FTU/g (P1), 500 FTU/g (P2), 750 FTU/g (P3), and 1,000 FTU/g (P4). Basal controls, which included a fish meal-based diet (S0), were not supplemented with phytase (P0). The result in Experiment 1 showed that there was a significant increase in whole-body protein and reduction in fat with phytase compared to a diet without phytase (P < 0.05). Serum total protein declined significantly with phytase supplementation (P < 0.05). Serum phosphorus and glucose were higher with phytase supplementation compared to control (P < 0.05). Bone minerals declined significantly with increasing level of soya bean compared to fish meal diet (P < 0.05). In Experiment 2, serum phosphorus was improved with phytase compared to control with no phytase (P > 0.05). A significant reduction in whole-body protein and increase in fat was observed for fish fed phytase diets compared to diets with no phytase, regardless of soya bean level (P < 0.05); however, ash content was improved with phytase (250 FTU/g) compared to control (P < 0.05). Phytase supplementation improved bone phosphorus (250 FTU/g), calcium (250 FTU/g), magnesium (250–500 FTU/g), and zinc (250–1,000 FTU/g) compared to control (P < 0.05). In conclusion, the research has demonstrated that improved bone phosphorus (P) and growth could be achieved with the supplementation of dietary phytase.     

Effects of fish meal replacement with animal protein blend on growth performance,nutrient digestibility and body composition of juvenile Chinese soft‐shelled turtle Pelodiscus sinensis

An 8‐week feeding trial was conducted to evaluate the potential of partial replacement of fish meal with rendered animal protein blend (APB) [meat and bone meal (MBM): expanding blood meal (EBM) = 4 : 1] in the diet of juvenile Chinese soft‐shelled turtle Pelodiscus sinensis. Seven isonitrogenous and isoenergetic practical diets replacing 0%, 10%, 20%, 30%, 40%, 50% and 60% fish meal protein by APB were formulated. Weight gain, feed efficiency, protein efficiency and the apparent digestibility coefficients (ADCs) of dry matter and gross energy in the experimental diets all exhibited no significant difference (P > 0.05) when dietary fish meal was replaced for 0–40%, but decreased significantly (P < 0.05) with further increasing substitution levels. However, relative feed intake, ADC of lipid as well as the contents of whole‐body moisture, protein, lipid and ash all showed little differences (P > 0.05) among all the treatments. Nitrogen retention and the ADCs of protein and most amino acids all decreased significantly (P < 0.05) when fish meal was substituted by more than 30%. The results indicated that fish meal in the practical diet of juvenile Chinese soft‐shelled turtle could be replaced by 30–40% using a combination of MBM and EBM without negative effects on growth performance, nutrients digestibility and body composition.     

Utilization of Caridina nilotica (Roux) meal as a protein ingredient in feeds for Nile tilapia (Oreochromis niloticus)

The effects of replacing fish meal with Caridina nilotica as a protein ingredient on growth performance, nutrient utilization, carcass, proximate composition and economic benefits in Nile tilapia (Oreochromis niloticus) culture was evaluated. Replacement of the FM with C. nilotica was done at 25%, 50%, 75% and 100% (D25, D50, D75 and D100) and the substitution effects was compared with the control diet (D0, 0% C. nilotica). After 140 days of culture, the best growth performance, nutrient utilization and economic benefits occurred in fish groups fed diets with 25% C. nilotica inclusion. However, growth performance in fish fed diets D50 and D75 were comparable with the control (P > 0.05). At 100% substitution level of FM with C. nilotica, the growth performance and fish survival was lower than control. Protein and lipid contents in the fish and their digestibilities were highest in diet D25 and decreased with increasing levels of substitution of FM with C. nilotica. This study demonstrate that utilization of local protein sources (C. nilotica) can be effectively used to replace up to 75% of FM in the diets without compromising growth performance, survival, nutrient utilization and economic benefits in O. niloticus culture.     

Effect of feeding various levels of poultry by‐product meal on the blood parameters,filet composition and structure of female tenches (Tinca tinca)

Homogeneous background (age, sex, genetic lineage, culture conditions) was created to clearly demonstrate the impact of the tested dietary treatments. No feeds optimized for the rearing of the tench (Tinca tinca L. 1758) are available. Feeds are formulated to increase the growth rate or eliminate skeletal deformations. With the increasing prices of the basic components, fish meal (FM) and fish oil, poultry by‐product meal (PBM) can be used. The aim of the study was to evaluate the effects of substitution of FM with PBM on the tench blood parameters, body composition and structure of skeletal muscles. Cage‐reared female tenches (325 ± 18 g) were fed for 86 days with five types of feeds with 0% (control), 25.7%, 48.6%, 71.4% and 100% substitution of FM with PBM. No significant differences between the formulations were reported for weight, total length, fillet weight, visceral, liver, gonado‐somatic, proximate composition and biochemical blood parameters. However, significant differences were found in the fillet profiles of fatty acids—an increase in the PBM content correlated with an increase in saturated and monounsaturated fatty acids and a decrease in n‐3 PUFA and, generally, n‐6 PUFA. Significant differences were also observed in, for example, the content of intramuscular fatty tissue and the level of organ lipidosis between the control variant (0% PBM) and that with 100% substitution. A sensory assessment indicated a higher gustatory value of the fillets in the case of feeds with 48.6% and 71.4% substitution.     

Oxidative effect of l -carnitine on energy metabolism in diploid and triploid rainbow trout ( Oncorhynchus mykiss ): impact on metabolites

l-Carnitine plays a key role in the regulation of energy metabolism and growth in fish. The aim of this study was to determine the effects of dietary l-carnitine levels on carnitine homeostasis and energy metabolism in diploid and triploid trout (Oncorhynchus mykiss). Diploid and triploid trout (29.5 ± 0.6 and 31.8 ± 0.5 g, respectively) were fed with three diets supplemented with 15, 200 or 530 mg l-carnitine/kg, respectively, for 56 days. Compared to 15 mg l-carnitine, total carnitine content increased in the liver by 182% in diploid and by 154% in triploid trout fed 530 mg l-carnitine. In muscle, total carnitine content increased by 60 and 73% in diploid and by 34 and 75% in triploid with the increase in dietary l-carnitine levels. l-Carnitine caused no significant change in the plasma concentrations of metabolites like proteins (ammonia, urea and protein), lipid (triglycerides), carbohydrate (glucose, lactate) and enzyme activities (lipase, lactate, alanine transaminase, lactic acid dehydrogenase). Triploid trout had significantly lower plasma ammonia (P = 0.003), lipase (P = 0.005) and triiodothyronine (T3; P = 0.003) levels than diploid trout. In conclusion, ploidy significantly affected the energy metabolism in rainbow trout, dietary l-carnitine levels altered the l-carnitine homeostasis, but not influence nutritional metabolism.     

Effect of dietary Aloe vera polysaccharides supplementation on growth performance,feed utilization,hemato-biochemical parameters,and survival at low pH in African catfish ( Clarias gariepinus ) fingerlings

This study evaluated the effects of dietary Aloe vera polysaccharides on growth performance, feed utilization, hemato-biochemical parameters, and resistance against low water pH in African catfish (Clarias gariepinus) fingerlings. Fish were divided into five triplicate groups before being fed feeds supplemented with 0% (control), 0.5%, 1.0%, 2.0%, and 4.0% A. vera/kg diet for 8 weeks. Fish fed 1.0% A. vera/kg diet had significantly increased (P < 0.05) growth parameters (i.e., final weight, weight gain, absolute growth rate, and specific growth rate) compared to unsupplemented ones. Among dietary groups, significantly lower feed conversion ratio was presented in fish fed 1.0% followed by those fed 0.5, 2.0%, and 4.0% A. vera/kg diet (P < 0.05). The protein efficiency ratio was significantly higher (P < 0.05) in fish fed 1.0% A. vera/kg diet compared to unsupplemented fish and those fed 4.0% A. vera/kg diet, respectively. Dietary A. vera polysaccharide crude extracts requirement suitable for growth and feed utilization was estimated to be between 1.76 and 1.79% A. vera/kg diet. Overall, A. vera extracts had improved hemato-biochemical indices when compared to unsupplemented fish, and decreased some of the indices, especially at high dietary inclusion level (4%/kg diet). Furthermore, A. vera-supplemented fish had higher survival probability throughout the low water pH challenge period, except those fed 4% A. vera/kg diet and control diet.     

Effect of replacing fish meal with soybean meal on growth,feed utilization and nitrogen and phosphorus excretion on rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis>)

The effect of replacing fish meal with soybean meal (SBM) pretreated with phytase on feeds of juvenile rainbow trout was evaluated in a 90-day feeding trial. The rainbow trout (initial body weight, 4.01 ± 0.02 g) were fed five isonitrogenous (crude protein, 44.97%) and isolipidic (crude lipid, 13.42%) feeds. Diets were formulated to contain phytase-pretreated SBM replacing 0, 20, 40, 60 and 80% of fish meal protein, respectively. The results showed that there was no significant difference in weight gain (WG) among fish fed S0, S20, S40 and S60 diets; however, a significant reduction of this variable occurred when 80% of fish meal protein was replaced by phytase-treated SBM (P < 0.05). Similarly, specific growth rate and protein efficiency ratio had a similar trend with WG. Apparent digestibility coefficient (ADC) of protein and lipid in the S80 diet was significantly lower than that of the other diets, and the ADC of phosphorus significantly increased with the increase of dietary phytase-treated SBM level. No significant differences among treatments were detected for moisture, protein, lipid and ash content in whole body and muscle samples. Nitrogen and phosphorus excretion indicated that fish meal replacement by phytase-treated SBM led to an increase in nitrogen excretion, but led to a reduction in total phosphorus excretion. The results of the present study show that 60% of fish meal could be replaced by phytase-treated SBM in diets of juvenile rainbow trout without compromising weight gain or feed efficiency. A quadratic equation according to regression analysis of weight gain against dietary phytase-treated SBM level indicated that the optimal level of dietary phytase-treated SBM replacement for maximum growth was 26.90%.     

Fishmeal can be totally replaced by a mixture of rapeseed meal and Chlorella meal in diets for crucian carp (Carassius auratus gibelio)

This study was conducted to investigate the effects of dietary fishmeal (FM) replacement by a mixture of rapeseed meal and Chlorella meal (RCM) on growth performance, apparent digestibility coefficients (ADCs), digestive enzymatic activities and intestinal histology of crucian carp Carassius auratus gibelioi. Five isonitrogenous diets were formulated to replace 0% (RCM0), 25% (RCM25), 50% (RCM50), 75% (RCM75), and 100% (RCM100) of protein from fishmeal with RCM respectively. Each experimental diet was randomly assigned to triplicate groups with 25 juvenile fish (initial body weight: 1.77 ± 0.04 g) per fibreglass tank for 6 weeks. With increasing substitution levels, weight gain rate, specific growth rate, feed intake and protein efficiency ratio increased, but feed conversion rate decreased. Dietary RCM substitution improved lipid content of muscle, but had no significant effect on other proximate composition of muscle and liver. ADCs of dry matter, protein, lipid, energy and the majority of amino acids increased with increasing substitution level, and digestive enzyme activities (amylase, trypsin and lipase) in intestine showed the similar trend with ADCs. Dietary RCM substitution had no significant adverse effect on intestinal histology. This study indicated that FM protein could be completely replaced by mixed protein sources (RCM) in crucian carp diets.     

The effect of dietary cricket meal (<Emphasis Type="Italic">Gryllus bimaculatus</Emphasis>) on growth performance,antioxidant enzyme activities,and haematological response of African catfish (<Emphasis Type="Italic">Clarias gariepinus</Emphasis>)

This study was conducted to investigate the growth performance, biomarkers of oxidative stress, catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) as well as the haematological response of African catfish after being fed with fish feed containing different levels of cricket meal. The juvenile fish were assigned to three different treatments with isonitrogenous (35 %) and isoenergetic (19 kJ g^?1) diets containing 100 % cricket meal (100 % CM), 75 % cricket meal (75 % CM), and 100 % fishmeal (100 % FM) as control groups for 7 weeks. The results indicated that a diet containing 100 % CM and 75 % CM improved growth performance in terms of body weight gain and specific growth rate, when compared to 100 % FM. The feed conversion ratio (FCR) and protein efficiency ratio (PER) did not differ significantly between all diets, but reduced FCR and increased PER were observed with a higher inclusion of cricket meal. A haematological examination of fish demonstrated no significant difference of red blood cells in all diets and white blood cells showed a significantly higher value in fishmeal-fed fish. On the other hand, haemoglobin and haematocrit significantly increased with increasing amounts of cricket meal in the diet. Antioxidant activity of CAT was higher in the 100 % CM group compared to fish fed other diets, whereas GST and SOD showed increasing trends with a higher incorporation of cricket, although insignificant differences were observed between all diets. These results suggest that cricket meal could be an alternative to fishmeal as a protein source in the African catfish diet.     

Effects of replacement of animal protein by soybean meal on growth and carcass composition in juvenile Australian freshwater crayfish

A feed trial was conducted for 59 days with juvenile Cherax destructor, mean weight (se) 0.61 (0.01) g, reared communally and maintained on 16 isoenergetic diets containing crude protein levels of 15, 20, 25, and 30%. For each protein level the fish meal component was replaced by soybean meal to produce diets in which 0, 20, 40, or 60% of the protein originated from soybean meal. Mean percentage weight gain per day ranged from 2.98% (15% protein, 60% soybean meal diet), to 11.75% (30% protein, 40% soybean meal diet). When soybean meal was included at a level of 40–60%, growth rate was reduced relative to that achieved with control diets at 15% and 20% protein levels. In no case did a 20% substitution significantly affect growth over that achieved with controls. A two-way interaction occurred between dietary protein and the level of dietary soybean meal. Feeds of higher protein content appeared to permit higher soybean meal inclusion levels without significantly affecting growth. Increases of 5% protein produced a significant improvement in growth when soybean meal contributed from 40–60% of the total protein. This effect was less pronounced in the control diets and the 20% soybean meal series. The percentages of protein increased and lipid decreased in the carcass as the level of dietary protein increased. A similar effect occurred by increasing the soybean meal substitution level to 60%. An obvious trend in carcass moisture, energy, and ash did not occur. A protein requirement of 30% is apparent when fish meal and soybean meal are included in diets at levels of 20% and 24% respectively. A maximum weight of 14.13 g was recorded for an individual fed the 30% protein, 20% soybean meal diet.     

Effect of totally or partially replacing fish meal by alternative protein sources on growth of African catfish Clarias gariepinus (Burchell, 1822) reared in concrete tanks

A 12‐week feeding trial was carried out in concrete tanks to examine complete and partial replacement (75%) of fish meal (FM) with poultry by‐product meal (PBM), meat and bone meal (MBM) and soybean meal (SBM) in practical feeds for African catfish Clarias gariepinus. Triplicate groups of fish (initial body weight ranged from 90.33 to 93.93 g fish⁻¹) were fed seven isonitrogenous and isocaloric diets of 20% digestible protein and 300 kcal 100 g⁻¹ of digestible energy. The control contained 25% herring meal, whereas in the other six diets, PBM, MBM and SBM replaced 75% or 100% of the FM. Final body weight (FBW) and specific growth rate (SGR) of the fish fed diets containing PBM (75% and 100%), SBM (75% and 100%) and MBM (75%) were all higher, but not significantly different than those for fish fed the control diet. Replacing 100% of the FM by MBM significantly lowered FBW and SGR. Concerning whole body composition, there were no significant differences in ash and gross energy content of whole‐body among fish; fish fed diets containing PBM‐100% recorded significantly lower protein content compared with the control diet, while fish fed diet SBM‐100% recorded significantly lower moisture content compared with the control diet. Also fish fed diets SBM‐100% and PBM‐75% recorded higher lipid and gross energy contents compared with the control diet. The study revealed that satisfactory growth and feed utilization responses could be achieved through the replacement of FM by PBM, SBM and MBM in the diet of African catfish.     

Replacement of fish meal in practical diets for the Pacific white shrimp (Litopenaeus vannamei) reared under pond conditions

Increasing economical and ecological concerns regarding the use of fish meal in diets for marine shrimp have led to the development of replacement strategies where soybean meal has received ample attention. Most studies evaluating these strategies have been carried out under laboratory conditions which greatly differ from production conditions in ponds. This study evaluated a fish meal replacement strategy using vegetable protein sources in practical feeds for marine shrimp reared in ponds. Juvenile Pacific white shrimp (Litopenaeus vannamei) (0.03 g) were stocked into 16 0.1-ha low-water exchange ponds and reared over an 18-week period. Four commercially extruded diets formulated to contain 35% crude protein and 8% lipids were evaluated. These diets included varying levels of fish meal (9, 6, 3, and 0%) which was replaced by a combination of increasing levels of soybean meal (32.5, 34.9, 37.2 and 39.6% respectively) and corn gluten meal (0.0, 1.7, 3.2, and 4.8% respectively) to replace the protein originating from fish meal. At the conclusion of the experimental period, there were no significant differences (P ≥ 0.05) in shrimp production among the test diets. Mean final yield, final weight, feed conversion ratio and survival values ranged from 5363–6548 kg ha^− 1, 18.4–20.7 g, 1.38–1.12 and 84.0–94.0%, respectively. Although not significant, as higher levels of plant protein sources were included in the diets, the economic analysis showed a general increase in the partial gross returns of shrimp production. Results from this study demonstrate that fish meal can be completely replaced using alternative vegetable protein sources in practical shrimp feeds without compromising production and economic performance of L. vannamei reared in ponds.     

Partial Replacement of Fish Meal with Corn Gluten Meal in Diets for Japanese Flounder Paralichthys olivaceus

Abstract.— Feeding experiments were conducted to evaluate corn gluten meal (CGM) as an alternative protein source for fish meal in the diet of Japanese flounder Paralichthys olivaceus . A diet containing 75% white fish meal as a sole protein source was the control, and 20, 40, and 60% of fish meal protein was replaced with CGM protein in the experimental feeds. Juvenile fish of about 8 g initial body weight were fed each diet to apparent satiation twice a day. 6 d per week for 8 wk at 20 C. Survival rates of fish ranged from 98 to 100% and were not significantly different ( P > 0.05) among treatments. Final body weight, weight gain, feed efficiency and protein efficiency ratio of fish fed the diets containing CGM up to 40% substitution levels were not statistically different from those of fish fed the control diet. All production parameters for fish fed the diet replacing 60% of fish meal protein were significantly lower than the control ( P ≤ 0.05). Supplements of crystalline amino acids to the CGM diet improved the nutritive value of the diet. Since substitution up to 40% did not adversely affect hematological and hematochemical parameters as well as whole body composition of the cultured fish, it is suggested that up to 40% of fish meal protein can be replaced with CGM in the diet of juvenile Japanese flounder.     

Nutritional effects of protein source in starter diets for channel catfish (Ictalurus punctatus Rafinesque) in suboptimal water temperature

Intensive tank rearing of channel catfish (Ictalurus punctatus Rafinesque) fry can be successfully accomplished with commonly available ‘salmonid’ starter diets. Ingredient substitution in starter diets is less important from the cost perspective but growth, survival and health of fish are major concerns. Several combinations of fish meals and animal protein substitutes were evaluated in diet formulations for hatchery rearing of catfish fry. Sub‐optimal thermal conditions were used which are characteristic for the north‐central USA where catfish culture is important for stocking purposes and live‐fish markets. A diet formulated on the basis of menhaden fish meal (29.1%), herring fish meal (25.1%) and animal by‐product mixture (16.38%) gave numerically the highest growth rate after 13 weeks of feeding, although growth reductions in fish fed diets exclusively with mehaden meal (77.6%) as protein or substituted with 50% animal by‐product protein were not significant. Instantaneous mortality rates were the highest between weeks 2 and 4 of rearing and increased almost proportionally with the increased fish meal protein substitution. A diet based on menhaden fish meal had the highest concentration of phosphorus and several other essential minerals, but these were not reflected in the mineral composition of the fish body at the termination of feeding. Among activities of digestive enzymes, trypsin was depressed in fish offered diets with 75–100% fish meal protein replacement. A diet superior in terms of fish performance was defined in the present study and it was concluded that the initial feeding can greatly affect physiological status of juvenile channel catfish.     

Replacement of fish meal with poultry by-product meal in diets formulated for the humpback grouper, Cromileptes altivelis

An eight-week feeding trial was conducted to examine the possibility of replacing fish meal with poultry by-product meal (PBM) at high inclusion levels in the diets of the humpback grouper, Cromileptes altivelis, a carnivorous marine tropical fish. Six isolipidic (12%) and isoproteic (50%), experimental diets were formulated to contain graded levels of PBM. Fish meal protein was replaced with a feed-grade PBM at 50, 75 or 100% level (FPBM50, FPBM75, FPBM100, respectively), or a pet food grade PBM at 75 or 100% replacement level (PPBM75 and PPBM100, respectively). The control diet contained Danish fish meal as the sole protein source. The experimental diets were fed close to apparent satiation, twice a day to triplicate groups of humpback grouper fingerlings (12.4 ± 0.2 g). The grouper fingerlings were randomly distributed into groups of 15 fish in cylindrical cages (61 cm depth and 43 cm diameter) and placed in a 150-ton seawater polyethylene tank. Except for fish fed the FPBM100 diet, growth performance, survival, and feed utilization efficiency for fish fed PBM-based diets were not significantly lower (P > 0.05) compared to fish fed the control diet. The PBM source and dietary level did not significantly affect (P > 0.05) the hepato- and visero-somatic indices or the condition factor of fish. Dry matter and protein apparent digestibility coefficients (ADC) of the diets decreased with increasing dietary PBM, and ranged from 64.3-71.5% and 86.2 to 91.2%, respectively. High values (91.7 to 96.7%) for lipid ADC were observed in all diets, with no significant differences among dietary treatments. Whole-body moisture and lipid contents of the fish were not affected by the inclusion of PBM in the diets. With the exception of fish fed the FPBM100 diet, whole-body protein of fish fed the PBM-based diets was slightly higher than that of fish fed the control diet. There was a trend of increased whole-body ash with the increase in dietary levels of PBM. The results from this study indicate that good quality terrestrial PBM can successfully replace more than half the protein from marine fish meal in the diets for humpback grouper. However, total replacement of fish meal with PBM might be constrained by lowered nutrient digestibility and limiting essential amino acids, especially lysine and methionine.     

Evaluation of corn steep liquor as a supplementary feed for Labeo rohita (Ham.) fingerlings

The effects of corn steep liquor (CSL), a by-product of corn starch industry, in the fish diet at 25% (D1), 50% (D2) and 75% (D3) replacement of fish meal are investigated on the growth of Labeo rohita (rohu) fingerlings. Formulated feeds were iso-nitrogenous (39% crude protein) and iso-energetic (15.8?kJ/g). The CSL is found to be rich in protein (43.48%), lactic acid (20.79%) and minerals and is free from fibres, phytic acid and trypsin inhibitors. The sulphur amino acid content of CSL is found to be 2.43%, though it is deficient in lysine (0.73%). With diets D1 and D2, growth performance and feed efficiency in terms of weight gain, specific growth rate (SGR), feed intake, feed conversion ratio (FCR) and protein efficiency ratio (PER) as well as apparent digestibility (APD and ALD) were higher when compared to CD. With diet D3, they were similar to CD. Up to 50% level of CSL in the diets (D1 and D2), the protein and lipid contents of carcass were significantly higher (P?<?0.05) when compared to CD. The digestive enzyme activities are found to be similar in all the diet groups. The findings suggest that in the diet of rohu, fish meal can be replaced up to 75% level with CSL without hampering the growth of the fishes. The CSL appear to be a better plant protein source as partial replacement of fish meal.     

Replacement of Fish Meal with Salicornia Meal in Feeds for Nile Tilapia Oreochromis niloticus

Abstract.— We investigated the use of the halophyte salicornia Sulicornia bigelovii as a replacement for fish meal in feeds containing 35% crude protein for Nile tilapia Oreochromis niloticus . Five isocaloric, isonitrogenous diets were formulated with salicornia meal to replace 0%. 20%. 40%. 60%. and 80% of the fish meal in the feed. Another diet was formulated entirely from salicornia meal. Diets were fed to three replicate groups of tilapia fingerlings (mean initial weight = 0.5 g/fish) for 6 wk in 40-L aquaria supplied with 22 C well water. Tilapia growth did not differ ( P < 0.05) for fish fed diets in which 0%. 20%. or 40% of the fish meal in the diet was replaced with salicornia meal. Weight gain was reduced when fish were fed diets with higher levels of salicornia meal, and growth was slowest for fish fed diets formulated entirely from salicornia meal. Body fat was reduced and body moisture content was increased ( P < 0.05) for fish fed diets in which more than 80% of the fish meal was replaced with salicornia meal. We conclude that salicornia meal can replace up to 40% of the fish meal in O. niloticus feeds without affecting growth or body composition.