Effect of feeding level on feed losses and feed utilization of soya and fish meal diets in Colossoma macropomum (Cuvier)

Juvenile, 1-g Colossoma macropomum (Cuvier) were fed two different diets: one with fish meal and another with soya meal as the main dietary protein source. Both diets were provided at ad libitum feeding level, and at two restricted feeding levels of ～ 80% and 60% of the ad libitum level. The experiment was performed in 30 aquaria, each stocked with 12 fish. For each treatment (two diets X three feeding levels), there were five replicates. Fish were fed three times daily at 0900, 1300 and 1700 h. At sampling days (days 14, 29, 44) in each aquarium in one of these feedings, chromic-oxide-marked feed was used. Shortly after the last meal, fish were weighed and four fish were taken from each aquarium for determination of the chromic oxide content in their digestive tract. Fish fed the fish meal diet attained a higher weight but had a lower body protein content. At the ad libitum feeding level, feed intake of the fish meal diet was higher, but feed and protein utilization efficiency were lower than with the soya diet. However, statistical analysis of the data of both the ad libitum and the two restricted feeding levels revealed that the reduced voluntary feed intake of the soya diet was the cause of its better utilization with ad libitum feeding. There is no evidence that soya protein is more freely available than fish meal protein. The chromic oxide data showed that 15 min after feeding, all of the feed (99.8%) could be traced back in fish fed the lowest feeding level, while at the ad libitum feeding level the recovery was only 72%. These data confirmed the hypothesis that at high feeding levels, considerable amounts of feed remain uneaten. Feed losses were not significantly different between the two diets. The chromic oxide recovery data of the 0900 h and 1300 h feedings showed that the feed passage rate in the digestive tract was similar for the three different feeding levels. Due to the high feed losses at high feeding levels, the relation between feed ration and feed utilization is determined mainly by the percentage of feed losses at the different feed rations.     

Effects of replacing fish meal with soybean meal and peanut meal on growth,feed utilization and haemolymph indexes for juvenile white shrimp Litopenaeus vannamei,Boone

An 8‐week feeding trial was conducted to evaluate the effects of replacing fish meal (FM) with soybean meal (SBM) and peanut meal (PM) on growth, feed utilization, body composition and haemolymph indexes of juvenile white shrimp Litopenaeus vannamei, Boone. Five diets were formulated: a control diet (FM30) containing 30% fish meal and four other diets (FM20, FM15, FM10 and FM5) in which protein from fish meal was substituted by protein from SBM and PM. The dietary amino acids of diets FM20, FM15, FM10 and FM5 were equal to those of the diet FM30 by adding crystalline amino acids (lysine and methionine). Each diet was randomly assigned to triplicate groups of 30 shrimps (initial weight = 0.48 g), each three times daily. The results indicated that shrimp fed the diets FM15, FM10 and FM5 had poor growth performance and feed utilization compared with shrimp fed the control diet. No difference was observed in feed intake, survival and body composition among dietary treatments. The plasma total cholesterol level of shrimp and the digestibility of dry matter, protein and energy contained in the diets decreased significantly with increasing PM and SBM inclusion levels. Results of this study suggested that fish meal can be reduced from 300 to 200 g kg^?1 when replaced by a mixture of SBM and PM.     

Effects of replacing fish meal with poultry by‐product meal and soybean meal and reduced protein level on the performance and immune status of pond‐grown sunshine bass (Morone chrysops × M. saxatilis)

Two primary ways to achieve low‐cost, nutritionally efficacious diets for sunshine bass (Morone chrysops × M. saxatilis) are to decrease crude protein (CP) levels and the use alternative animal or plant ingredients to partially, or totally, replace fish meal. A 459‐day feeding trial was conducted with juvenile (35 g) sunshine bass to evaluate growth, feed efficiency, size distribution at harvest, immune function status and body composition when fed diets containing soybean meal (SBM), feed‐grade poultry by‐product meal (PBM), and supplemental methionine as complete replacements for menhaden fish meal (MFM) at 300 g kg^?1 diet, while simultaneously reducing dietary crude protein (CP; 320, 360, and 400 g kg^?1). The feeding trial was conducted in 12, 0.04‐ha earthen ponds stocked at a rate of 300 per pond (3000/ac). At 400 g kg^?1 dietary protein, there were no differences in responses between fish fed the diet containing MFM or the diet in which MFM was completely replaced with PBM and supplemental methionine on a digestible protein basis. However, final mean weight, percentage weight gain, specific growth rate, and protein efficiency ratio were linearly related (P < 0.10) to dietary protein level in the diets while no significant differences were found in feed intake and feed conversion ratio. The expected odds of fish at harvest being classified into larger size categories (> 680 g) decreased as dietary protein level decreased based on ordinal logistic regression. There were no significant relationships between body compositional indices and dietary treatments. Body fat ranged from 56 g kg^?1 to 62 g kg^?1, single fillets ranged from 28% to 30%, and livers ranged from 2.45% to 2.62% of body weight across treatments. Fillet protein concentration was positively linear and quadratic for protein level in the diet but fillet moisture, lipid and ash did not differ among diets. Total serum protein, immunoglobulin and lysozyme activity decreased linearly with decreasing diet protein level. These results suggest that complete replacement of MFM with feed grade PBM and supplemental methionine is possible in diets for sunshine bass and that further reductions in dietary protein level may be possible with amino acid supplementation.     

Optimizing dietary protein sources for Japanese sea bass (Lateolabrax japonicus) with an emphasis on using poultry by‐product meal to substitute fish meal

This study evaluated the potential of using poultry by‐product meal (PBM) to replace fish meal in diets for Japanese sea bass, Lateolabrax japonicus. Fish (initial body weight 8.5 g fish^?1) were fed six isoproteic and isoenergetic diets in which fish meal level was reduced from 400 g kg^?1 (diet C) to 320 (diet PM1), 240 (diet PM2), 160 (diet PM3), 80 (diet PM4) or 0 g kg^?1 (diet PM5), using PBM as the fish meal substitute. The weight gain (WG), specific growth rate, nitrogen retention efficiency, energy retention efficiency and retention efficiency of indispensable amino acids were higher in fish fed PM1, PM2, PM3 and PM4 diets than in fish fed diets C or PM5. The phosphorus retention efficiency was lower in fish fed PM3, PM4 and PM5 diets than in fish fed C, PM1 or PM2 diets. Fish fed diet PM5 had the highest feed conversion ratio, total nitrogen waste output (TNW) and total phosphorus waste output (TPW) among the treatments. No significant differences were found in the hepatosomatic index or body contents of moisture, lipid and ash among the treatments. Fish fed diet C had lower condition factor and viscerosomatic index than those of fish fed PM1, PM3, PM4 and PM5 diets. The results of this study indicate that using fish meal and PBM in combination as the dietary protein source produced more benefits in the growth and feed utilization of Japanese sea bass than did using fish meal or PBM alone as the dietary protein source. The dietary fish meal level for Japanese sea bass can be reduced to 80 g kg^?1 if PBM is used as a fish meal substitute.     

Partial replacement of soybean meal by sesame meal in diets of juvenile Nile tilapia,Oreochromis niloticus L.

An 8‐week feeding trial was conducted to determine the effects of replacing of soybean meal (SBM) with sesame meal (SM) in the diets of Oreochromis niloticus fingerlings. Seven practical diets (33 g kg^?1 crude protein, 19.2 MJ kg^?1 dry diet) containing substitution levels of 0%, 8%, 16%, 24%, 32%, 40% and 48% SM for SBM protein were formulated and fed to triplicate groups of O. niloticus fingerlings (mean initial weight of 8.74 ± 0.12 g). The fish survival rate, hepatosomatic index, viscerosomatic index and condition factor were not significantly affected by the contents of SM in the diets (P>0.05). The final body weight, weight gain (WG), specific growth ratio, feed conversion ratio and protein efficiency ratio of the fish fed the diet containing 16% SM were similar (P>0.05) to that of the fish fed the control diet. Except lipid, digestible contents of dry matter, crude protein, ash, gross energy and individual amino acids decreased while phosphorous increased with increasing SM levels. No significant differences were observed in whole‐body dry matter, ash and lipid contents among all the treatments (P>0.05); crude protein contents between fish fed the control diet and a diet containing 24% SM were also not affected significantly (P>0.05), and the phosphorus content was not significantly different when the SM level was increased to 32% (P>0.05). No significant negative differences were observed in the liver composition between fish fed the control diet and the diet containing 24% SM. The most efficient diet in terms of cost per unit WG of fish was obtained in 8% SM dietary substitution, while no significant differences were found among the 0%, 8% and 16% levels. It was indicated that SM can be utilized in the juvenile Nile tilapia diet to replace about 16% of SBM protein without causing negative effects on growth performance, body composition, liver composition and feed utilization.     

The potential of pet‐grade poultry by‐product meal to replace fish meal in the diet of the juvenile spotted rose snapper Lutjanus guttatus (Steindachner, 1869)

A 12‐week feeding trial was conducted to examine the replacement of fish meal with pet‐grade poultry by‐product meal (PBM‐PG) in the spotted rose snapper Lutjanus guttatus diet. Five experimental diets were formulated to contain graded levels of PBM‐PG at proportion of 250, 500, 75 or 900 g kg^?1. The control diet contained sardine fish meal as the main protein source. Four groups of 15 randomly assigned L. guttatus juveniles were fed to satiation 3 times day^?1. Except for the fish fed the PBM‐PG90 diet, the growth performance, survival and feed utilization efficiency of the experimental fish were not significantly lower than those of the control fish. The dietary level of PBM‐PG did significantly affect the haematological characteristics (P < 0.05). The dietary dry matter and protein apparent digestibility coefficients (ADCs) decreased with increasing dietary PBM‐PG. High values for lipid ADCs were observed in all diets, with significant differences among the dietary treatments. The fish whole‐body protein, moisture, lipid and ash contents were not affected by the inclusion of dietary PBM. These results indicate that high‐quality terrestrial PBM can successfully replace more than half of the marine fish meal protein in the L. guttatus diet.     

Total replacement of fish meal with animal protein sources in Nile tilapia,Oreochromis niloticus (L.), feeds

The effects of total replacement of dietary fish meal (FM) with animal protein sources on the growth, feed efficiency and profit indices of Nile tilapia, Oreochromis niloticus (L.), were investigated. Shrimp meal (SM), blood meal (BM), meat and bone meal (MBM), BM + MBM mix and poultry by-product meal (PBM) replaced FM in six isonitrogenous (30% crude protein), isocaloric (400 kcal GE 100 g^–1) diets. The diets were fed to O. niloticus fingerlings (12.5 g) to satiation twice a day for 150 days. The growth of fish fed SM, PBM and MBM was not significantly different from those fed the FM-based diet, while feed conversion and protein efficiency ratios were significantly retarded. Further reduction in fish performance was noticed when BM or BM + MBM replaced FM in the control diet. Cost–benefit analyses of the test diets indicated that these sources were economically superior to FM. The PBM-based diet produced higher carcass lipid than other diets. Fish fed SM, MBM and PBM diets had significantly higher ash contents (P < 0.05).     

Effects of partial substitution of dietary fish meal by fermented soybean meal on growth performance,amino acid and biochemical parameters of juvenile black sea bream Acanthopagrus schlegeli

A feeding trial was conducted to evaluate the effect of replacing fish meal protein with fermented soybean meal (FSM) on the growth performance, feed utilization, amino acid profile, body composition, morphological parameters, activity of antioxidant and digestive enzymes of black sea bream (Acanthopagrus schlegeli) juvenile. Five isonitrogenic and isolipidic diets were prepared with levels of 0 (control), 80, 160, 240 and 320 g kg^?1 FSM. Triplicate groups (40 fish per tank) of juvenile black sea bream with initial weight of 1.17 ± 0.04 g were hand‐fed to visual satiation at three meals per day for 8 weeks. The fish fed diets containing different levels of FSM had no significant differences regarding survival and specific growth rate compared with control group. Feed and protein efficiency ratios of fish fed diet containing 320 g kg^?1 FSM were significantly lower than those of control group. Daily feed intake and daily protein intake of fish fed diet containing 240–320 g kg^?1 were significantly higher than those of control group. Hepatosomatic index and condition factor of fish were not affected by different dietary FSM level. Fish fed diets containing 240–320 g kg^?1 FSM had significantly higher visceral somatic index than control group. Whole body proximate and amino acid compositions of fish were not affected by dietary FSM level. The activity of digestive enzymes in the intestine was not affected by dietary FSM level. The activity of glutathione peroxidase in liver was significantly higher for fish fed the diet containing 160 g kg^?1 FSM compared with control group. This study showed that up to 40% fish meal in the diets of juvenile black sea bream could be replaced by fermented soybean meal with supplementation of methionine, lysine and taurine.     

Evaluation of potential of lupin meal as an alternative to fish meal in juvenile Penaeus monodon diets

An indoor feeding trial in a flow-through marine water system was performed to evaluate the feasibility of using dehulled lupin Lupinus albus seed meal as a protein source to replace fish meal in diets for the juvenile Penaeus monodon. Five isonitrogenous (40% crude protein) diets formulated by replacing 0, 25, 50, 75, and 100% of fish meal protein by lupin meal protein were fed to shrimp (mean initial weight of 4.32 ± 0.23 g) three times daily at a feeding allowance of 5% body weight per day for 42 days. Shrimp fed diets with 0, 25, 50 and 75% replacement had similar (P > 0.05) weight gain, dry matter feed intake, feed conversion ratio (FCR), protein efficiency ratio (PER), and apparent net protein utilization (ANPU). Shrimp fed the highest dietary inclusion level of lupin meal (100% replacement) had significantly (P < 0.05) lower responses for all the above parameters than shrimp fed all other diets. Survival was high (87–100%) and similar for all diets. Apparent dry matter digestibility (ADMD) of diets with 25, 50, 75 and 100% replacement of fish meal with lupin meal was similar (75.6–76.6%) and significantly (P < 0.05) higher than that of diet with 0% replacement (73.9%). Diets containing the two highest lupin inclusion levels (75 and 100% replacement) had significantly (P < 0.05) better apparent protein digestibility (APD) than those containing the two lowest lupin meal inclusion levels (0 and 25% replacement). There were no significant differences (P > 0.05) in whole-body composition (dry matter, protein, lipid and ash) of shrimp fed on the various diets. Pellet water stability was inversely related to level of lupin meal inclusion. It was found, in this study, that up to 75% protein of fish meal can be replaced with the protein of dehulled lupin seed meal in diets for juvenile P. monodon. The diet with total replacement of fish meal containing 40% lupin meal was utilized very poorly by the shrimp.     

Effect of dietary zinc level on growth,enzyme activity and body trace elements of hybrid tilapia,Oreochromis niloticus × O. aureus,fed soya bean meal‐based diets

A feeding experiment was conducted to determine the dietary zinc (Zn) requirement of hybrid tilapia fed on a diet with soya bean meal as the sole protein source. The quantity of phytic acid in the experimental diet was 15.5 g kg^?1. Juvenile hybrid tilapia were fed on diets containing 31–227 mg Zn kg^?1 in triplicates for 6 weeks. Haematology of the fish was not affected by various dietary Zn levels. Fish fed on a diet containing 31 mg kg^?1 endogenous Zn showed the lowest growth rates, feed utilization, and body and plasma Zn levels. Weight gain (WG), plasma Zn level and superoxide dismutase (SOD) activity increased when a higher quantity of dietary Zn of 127 mg kg^?1 was administered to the experimental fish. Beyond this level, the values of these parameters were relatively stable. On the other hand, within the dietary Zn range tested, whole‐body Zn and ash increased with higher dietary Zn levels. Analysis using a broken‐line model showed that the dietary Zn requirements of hybrid tilapia fed on soya bean meal‐based diets containing 15.5 g kg^?1 endogenous phytic acid were 115, 115 and 105 mg kg^?1 based on WG, whole‐body Zn retention and plasma Zn level, respectively.     

Evaluation of soybean meal in the formulated diets for juvenile Pangasianodon hypophthalmus (Sauvage, 1878)

The influence of soybean meal (SBM) on the growth and feed utilization of juvenile sutchi catfish (Pangasianodon hypophthalmus, Sauvage, 1878) was investigated. Eight isonitrogenous (300 g kg^?1 CP) and isoenergetic (18 MJ kg^?1) diets were formulated incorporating Argentine SBM to replace fish meal at 0, 150, 300, 450, 600, 750, 900 and 1000 g kg^?1 dietary protein. Each diet was fed to three replicate groups of fish with an initial weight 6.0–6.2 g for twelve weeks. Growth performance decreased, and feed utilization was worsened with the increase in SBM inclusion in the diets. Final weight and relative growth rate (RGR) of fish fed control diet (0 SBM) were significantly higher than those fed test diets (P < 0.05). However, there were no significant differences in the final weight and RGR between the fish fed on 15 SBM, 30 SBM, 45 SBM and 60 SBM diets. Specific growth rate of fish fed 0 SBM, 15 SBM, 30 SBM and 45 SBM diets was significantly higher than those fed other diets. Feed conversion ratio of fish fed 0 SBM, 15 SBM, 30 SBM, 45 SBM and 60 SBM diets was significantly lower than those fed other diets (P < 0.05). The dry matter and protein digestibility were lesser in all the diets in comparison with the control diet. Hepatosomatic index and viscerosomatic index increased with increasing SBM in diet. This present trial indicated that fish meal can be replaced by SBM in the diet of juvenile sutchi catfish only up to 45% of fish meal protein without any adverse effect on growth, feed utilization and body composition.     

Evaluation of micronized lupin seed meal as an alternative protein source in diets for gilthead sea bream Sparus aurata L. juveniles

A 12‐week growth trial was performed to evaluate the effect of lupin seed meal as a protein source in diets for gilthead sea bream (Sparus aurata) juveniles. Six experimental diets were formulated to be isonitrogenous and isoenergetic and to contain 10%, 20% and 30% of raw lupin (Lupinus angustifolius) seed meal protein or 20% and 30% lupin (L. angustifolius) seed meal processed by infrared radiation (micronized) in place of fish meal protein, the only protein source of the control diet. Fish accepted all diets well and no significant differences in feed utilization among groups were noticed during the trial. Final weight of fish fed the experimental diets was identical or higher than the control group. Final weight of fish fed diets including 20% micronized lupin protein was even significantly higher than that of fish fed the fish meal‐based control diet. Moreover, at the same dietary lupin seed meal protein inclusion levels, final weight of fish fed diets including micronized lupin was significantly higher than with raw lupin. A trend was also noticed for a decrease of final weight with the increase in lupin seed meal in the diets. At the end of the trial no significant differences in proximate whole‐body composition, hepatosomatic and visceral indices were observed among groups. It is concluded that lupin seed meal can replace up to 30% fish meal protein in diets for gilthead sea bream juveniles with no negative effects on growth performance. Furthermore, micronization of lupin seeds improves its dietary value for gilthead sea bream juveniles. At the same dietary lupin inclusion levels, diets including micronized lupin seeds promote significantly higher growth rates than raw lupin seeds.     

Use of cottonseed meal supplemented with iron for detoxification of gossypol as a total replacement of fish meal in Nile tilapia, Oreochromis niloticus (L.) diets

The objective of this study was to determine the effect of total replacement of fish meal by cottonseed meal (CSM) supplemented with various levels of iron in practical diets on growth performance, feed utilization, body composition and some biological and haematological parameters of Nile tilapia, Oreochromis niloticus (L.). Juvenile fish (average weight 3.78±0.1 g) were stocked in 18 glass aquariums (80 L each) at 25 fish per aquarium. Fish meal (50% of the diet) was used as the sole source of animal protein in the control diet 1. Diets 2–6 had 100% CSM (0.145% free gossypol) protein with various levels of supplemented iron (86, 486, 972, 1458 and 1944 mg Fe kg diet^?1) in diets 2–6 respectively. Diets were fed to fish twice daily at a rate of 3% of body weight during the first 12 weeks then 2% of the total fish biomass daily until the end of the experiment (30 weeks). The results of this study revealed that, groups of fish fed diets 1, 4, 5 and 6 had significantly (P≤0.01) the higher average body weight and specific growth rate than those of fish fed diet 2 (100% CSM without iron supplementation) and diet 3 (100% CSM plus 486 mg Fe kg diet^?1). The best values for feed conversion ratio, protein efficiency ratio and condition factor (K) were recorded with groups of fish fed diet 4 (100% CSM plus 972 mg Fe kg diet^?1). Red blood cell count, haematocrit and haemoglobin were increased with increasing levels of iron and significantly affected by dietary iron. Hepatosomatic index for diets 3–6 were not significantly different (P>0.05) and superior to that of diet 1 control [100% fish meal (FM)]. The gonadosomatic index of males of Nile tilapia was not influenced by CSM diets with or without iron, while females of Nile tilapia were significantly influenced with iron and the lowest values were recorded with groups of fish fed diet 2 (100% CSM without iron supplementation). Apparent digestibility coefficients of protein, fat dry matter and energy were relatively high for most diets supplemented with iron and increased by increasing iron supplementation. There were no significant differences between groups of fish fed diet 1 (100% FM) and diets 5 and 6 which contained 100% CSM with additional 1458 and 1944 mg Fe kg diet supplemental iron^?1 respectively. Proximate composition of whole body was not influenced by diet. Adding 972 mg Fe kg diet^?1 from ferrous sulphate to the CSM‐based diets that contained 972 mg free gossypol (1:1 iron to free gossypol ratio) for Nile tilapia reduce the negative effects of gossypol and improved growth performance, feed utilization and blood parameters and can totally replace fish meal in tilapia diets.     

Partial substitution of fish meal with soybean and cottonseed meals in diets for African bonytongue,Heterotis niloticus (Cuvier, 1829) fingerlings: effects on growth,feed efficiency and body composition

A feeding trial was conducted to examine the suitability of soybean meal (SBM) and cottonseed meal (CSM) as a partial substitute for the dietary protein supplied by fish meal for H. niloticus fingerlings. Fish were fed with four isonitrogenous (350 g kg^?1 crude protein) and isoenergetic (18.8 kJ g^?1 GE) diets in which fish meal protein was gradually replaced by plant protein from a mixture of SBM and CSM (0%, 25%, 50% and 75% in diets 1, 2, 3 and 4 respectively). Triplicate groups of fingerlings H. niloticus (mean weight of 5 g) were handfed twice daily to apparent satiation for 60 days inside net hapas. Growth performances (SGR varied from 3.09% to 3.16% day^?1) of fingerlings fed diets containing 0%, 25% and 50% plant protein were not significantly different (P>0.05). At 75% fish meal substitution, growth and feed utilization efficiency indicators were significantly reduced (P<0.05). The carcass composition were also significantly (P<0.05) affected by the replacement level of fish meal, except dry matter and ash. Results suggest that the dietary fish meal protein could efficiently be substituted by a mixture of soybean and cottonseed meals up to 50%, without adverse effects on maximal growth in practical diets for H. niloticus fingerlings.     

Incorporation of a mixture of meat and bone meal,poultry by‐product meal,blood meal and corn gluten meal as a replacement for fish meal in practical diets of Pacific white shrimp Litopenaeus vannamei at two dietary protein levels

A 6‐week feeding trial was carried out in glass tanks to determine the effects of partial replacement of fish meal (FM) with a combination of meat and bone meal (MBM), poultry by‐product meal (PBM), blood meal (BM) and corn gluten meal (CGM) in practical diets on the growth, nutrient digestibility and body composition of Pacific white shrimp. Six practical diets were formulated, containing two levels of crude protein (CP) (330 and 380 g kg^?1) and similar crude lipid (CL) levels. For the 330 g kg^?1 dietary protein level, 0, 357 and 714 g kg^?1 FM were replaced by the mixture in Diets 1–3, respectively; while 0, 514 and 784 g kg^?1 FM were replaced in Diets 4–6, respectively, for 380 g kg^?1 dietary protein level. White shrimp‐fed diets containing 330 g kg^?1 CP had significantly lower weight gain compared with white shrimp fed diets containing 380 g kg^?1 CP. Increasing the mixture and dietary protein level significantly raised the body ash content of white shrimp. White shrimp fed a low‐protein diet obtained better nutrient digestibility compared with those fed a high‐protein diet.     

不同饲料蛋白水平下点带石斑鱼对鸡肉粉、羽毛粉和血粉混合物的利用能力

通过10周网箱养殖实验,评价了不同饲料蛋白水平下点带石斑鱼对1种鸡肉粉、羽毛粉和血粉混合物的利用能力。采用2×4实验设计,设2个饲料蛋白水平(490 g/kg和530 g/kg粗蛋白),每个饲料蛋白水平下设4个鱼粉水平,其中1组饲料中加入500 g/kg鱼粉(对照),另外3组饲料中分别加入139、278、416 g/kg的鸡肉粉、羽毛粉和血粉混合物(鸡肉粉∶羽毛粉∶血粉=65∶20∶15)替代对照饲料中30%、60%、90%的鱼粉。实验鱼初始体重为(33.4±0.1) g。实验期间,除恶劣天气外,每天分两次按饱食量投喂实验鱼。实验结果表明,饲料蛋白水平对摄食量、增重,饲料系数、氮储积效率、能量储积效率和鱼体组成无显著影响;饲料鱼粉含量显著影响增重,饲料系数、氮储积效率和能量储积效率,但对摄食量和鱼体组成无显著影响。在相同饲料蛋白水平下,特定生长率(SGR)随鱼粉含量降低而下降;当鱼粉含量相同时,摄食高蛋白饲料的鱼SGR略高于摄食低蛋白饲料的鱼。本实验结果显示,通过添加鸡肉粉、羽毛粉和血粉混合物可将点带石斑鱼饲料鱼粉含量降低到200 g/kg,在490~530 g/kg范围内提高饲料蛋白水平无助于降低点带石斑鱼饲料鱼粉含量。     

Replacement of by-catch fishmeal with dried chicken viscera meal in extruded feeds: effect on growth,nutrient utilisation and carcass composition of catfish <Emphasis Type="Italic">Clarias batrachus</Emphasis> (Linn.) fingerlings

An 84-day feeding trial was conducted to study the effect of replacing dietary fishmeal with dried chicken viscera meal (CVM) on the growth (net biomass gain, specific growth rate, SGR), feed acceptability, feed conversion ratio (FCR), protein efficiency ratio (PER) and carcass composition of Clarias batrachus fingerlings. Triplicate groups of fingerlings with mean initial body weight of 13.35 g were fed on six iso-nitrogenous and iso-lipidic diets. The control diet (CVM0) used marine by-catch fishmeal as the sole source of animal protein. In the other five diets (CVM100–CVM500), 20–100% of fishmeal was substituted by dried CVM at 20% increments. The highest body weight gain, SGR and PER, and the lowest FCR were observed in fish fed a diet containing 300–500 g CVM kg⁻¹. The fish accumulated increasing quantities of lipids and decreasing levels of ash in their carcasses with increasing levels of dietary CVM.     

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.     

Supplementation of various meals to fish meal diet for chum salmon fry

In a 6-week feeding experiment, chum salmon, Oncorhynchus keta, swim-up fry, were fed fish meal diets supplemented with silkworm pupae powder (5%), dried beef liver (5%), krill meal (5%) or earthworm powder (5%) at the expense of fish meal, or substituting glucose (13%) for dextrin. Fish fed the diet with earthworm powder showed the best growth performance (675% weight gain in 6 weeks) and feed efficiency (117%). The growth rate and feed efficiency of the krill meal group were also significantly better than those of the control group (without supplement or substitution). Substitution of glucose and supplementation of silkworm pupae or beef liver failed to improve the growth rate, but significantly improved feed efficiency. Food consumption of fish fed the diet supplemented with earthworms was lowest, and none of the dietary treatments appreciably increased food intake of the fish over that of the control group. The dietary group receiving earthworm powder also showed significantly higher body fat content than the remaining dietary groups. No significant differences were noted in body protein and ash contents among all dietary treatments.