Effects of replacement of fish meal with fermented cottonseed meal on growth performance,body composition and haemolymph indexes of Pacific white shrimp,Litopenaeus vannamei Boone, 1931

A feeding trial was performed for 28 days to evaluate the effects of replacement of fish meal (FM) with fermented cottonseed meal (FCM) on growth, body composition and haemolymph indexes of juvenile Litopenaeus vannamei. Four isonitrogenous and isoenergetic diets were formulated by using FCM (96.4, 206, 317 and 417 g kg^?1) to substitute 25%, 50%, 75% and 100% of FM in a control diet respectively. Each diet was randomly allotted to four tanks with 20 shrimp per tank. The feeding trail was conducted in an indoor flow‐through aquaculture system. Shrimp fed diets containing 317 and 417 g kg^?1 of FCM obtained lower (P < 0.05) final weight, weight gain, specific growth ratio, protein efficiency ratio as well as a higher (P < 0.05) feed conversion ratio compared with shrimp fed the control diet. The body ash content decreased (P < 0.05) in shrimp fed the diet with complete replacement of FM than those in other treatments. Moreover, increasing the dietary inclusion of FCM linearly raised (P < 0.05) the concentrations of total gossypol, (?) and (+) gossypol enantiomers in the whole shrimp body. No difference (P > 0.05) was observed in haematological parameters among the treatments. The results suggest that up to 50% of FM can be replaced by FCM without adverse effects on growth and feed utilization of L. vannamei.     

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

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

Evaluation of cottonseed meal derived from genetically modified cotton as feed ingredients for channel catfish,Ictalurus punctatus

Three laboratory experiments were conducted to assess nutritional quality of cottonseed meals from genetically modified (GM) cotton crops, Roundup Ready^® Flex, Bollgard^® × Roundup Ready, Bollgard II^® × Roundup Ready, and Bollgard II × Roundup Ready Flex for channel catfish, Ictalurus punctatus using Good Laboratory Practices. Growth, feed efficiency, survival, and fillet composition of catfish fed diets containing 20% cottonseed meal from these cotton products were compared with that of catfish fed diets containing cottonseed meals from the near‐isogenic, non‐GM control and non‐GM commercial varieties. Juvenile catfish (mean weights of 4.1, 5.0, and 0.6 g per fish for Experiments 1, 2, and 3, respectively) were stocked in each of 80‐L aquaria and fed experimental diets for 8 weeks. Although there were slight variations in proximate composition, amino acids, and gossypol concentrations, the GM cottonseed meals were not significantly different from the conventional control and the reference cottonseed meals. Weight gain, feed conversion, survival, and fillet composition of catfish fed GM cottonseed meals appeared similar to that of either the control or the commercial cottonseed meals. Results from the present study demonstrate that these GM cottonseed meals are nutritionally equivalent to conventional non‐GM cotton varieties when fed to catfish at 20% of the diet.     

Hydrolysed fish protein concentrate (FPC) reduces viscera mass in Atlantic salmon (Salmo salar) fed plant‐protein‐based diets

Atlantic salmon fed diets devoid of fishmeal but added 0.5 g  kg^?1 fish protein concentrate (FPC) showed reduced growth and lipid deposition without affecting protein accretion as compared to fish fed a fishmeal‐based control diet. The aim of the current study was to assess whether higher inclusion of FPC improved the growth and lipid deposition of Atlantic salmon (initial body weight 380 g) fed high plant protein diets. Quadruplicate groups of fish were fed diets containing 200 g kg^?1 fishmeal of which was replaced with FPC (150, 112, 75, 38 and 0 g kg^?1) for a period of 79 days. The rest of the diet protein was a mixture of plant proteins. The lipid source used was fish oil. A fishmeal‐based diet was included as a positive control for growth performance. None of the test diets differed from the positive control‐fed fish in voluntary feed intake, growth performance or nutrient accretion. Thus, the test diets were found appropriate to assess the effect of FPC inclusion. Replacement of fishmeal with increasing concentration of FPC did not affect voluntary feed intake (P = 0.56), but growth performance decreased (P = 0.02) resulting in an increased feed conversion ratio (P = 0.003). Viscerosomatic index decreased as diet FPC inclusion increased (P = 0.012) without affecting the dress out weight (P = 0.08). Thus, the apparently improved growth in fish fed the diets with the low FPC inclusion was because of a higher visceral mass. Possible reasons for the reduced visceral mass following addition of FPC to high plant protein diets are discussed.     

Effects of feeding glandless or glanded cottonseed products and gossypol to Tilapia aurea

Seven isocaloric and isonitrogenous practical diets in which either glanded or glandless cottonseed products were substituted for soybean and/or peanut meals, and three purified diets containing graded levels of gossypol were fed to fingerling Tilapia aurea for a period of 10 weeks. Growth, feed conversion and survival data indicated that glanded and glandless cottonseed products were not as high in nutritive value for tilapia as are soybean and peanut meals. The inferior performance of fish fed cottonseed protein did not appear to be related to dietary gossypol. Carcass fatty acids generally reflected dietary fatty acids. An increase in palmitic and linoleic fatty acids was observed in fish fed fullfat, glandless cottonseed flour.     

Growth performance and expression of immune‐regulatory genes in rainbow trout (Oncorhynchus mykiss) juveniles fed extruded diets with varying levels of lupin (Lupinus albus), peas (Pisum sativum) and rapeseed (Brassica napus)

Varying levels of lupin (Lupinus albus), peas (Pisum sativum) and rapeseed (Brassica napus) meals were evaluated as partial replacements for fishmeal in extruded diets for rainbow trout, with particular emphasis on the effect on growth performance and the expression of three genes associated with immune response. A series of 10 isonitrogenous (450 g kg^?1 crude protein) and isolipidic (17 g kg^?1 crude lipid) diets were formulated to contain different levels of lupin (150 g kg^?1, 250 g kg^?1 and 350 g kg^?1), rapeseed cake (100 g kg^?1, 200 g kg^?1 and 300 g kg^?1) and pea (50 g kg^?1, 150 g kg^?1 and 250 g kg^?1) meals. The control diet was prepared with fish meal as the sole source of protein. Triplicate groups of fish (37.08 ± 3.58 g) were assigned to each experimental diet. The feeding experiment was conducted for 9 weeks at 14.3 ± 0.4 °C. The fish were hand fed three times per day, 6 days per week to apparent satiation level. Growth performance, feed utilization and immunological response were significantly affected by the type of plant protein as well as level of inclusion. Hepatosomatic index (HSI) increased in all groups of fish fed diets with pea and rapeseed cake meal. Dietary inclusion of lupin did not affect the expression of Mx‐1 gene. Our results suggest that fish meal can be replaced by lupin in the diet of rainbow trout without any apparent adverse effects on key innate immunological genes.     

A comparison of the effect of dietary fungal phytase and dicalcium phosphate supplementation on growth performances,feed and phosphorus utilization of tra catfish juveniles (Pangasianodon hypophthalmus Sauvage, 1878)

Six isonitrogenous (320 g kg^?1) and isolipidic (60 g kg^?1) diets were formulated with graded levels (0, 5, 10 and 15 g kg^?1) of dicalcium phosphate (DCP) and fungal phytase (750 and 1500 FTU kg^?1 diet). Tra catfish (Pangasianodon hypophthalmus), 9.6 g, were fed the diets for 12 weeks. Each experimental diet was fed to eight replicates of fish to apparent satiation. At the end of the trial, fish fed the diets containing 15 g kg^?1 DCP, 750 and 1500 FTU kg^?1 phytase had higher growth performances, protein efficiency ratio and phosphorus retention than those fed the control diet, 5 g kg^?1 DCP and 10 g kg^?1 DCP diets (P < 0.05). Whole body ash and phosphorus concentration of fish fed the 10 g kg^?1 DCP and 15 g kg^?1 DCP diets were significantly higher than those of fish fed the control diet. Higher apparent digestibility coefficient of phosphorus was observed in fish fed the phytase supplemented diets. The present results indicate that supplementation of phytase at 750 FTU kg^?1 and 1500 FTU kg^?1 improves growth performances, feed and phosphorus utilization. The supplementation can completely replace dicalcium phosphate or other phosphorus sources in tra catfish feed and reduce the phosphorus discharge into environment.     

Quantitative dietary leucine requirement of juvenile Pacific white shrimp,Litopenaeus vannamei (Boone) reared in low‐salinity water

The experiment was conducted to determine the leucine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low‐salinity water (0.50–1.20 g L^?1). Six diets were formulated to contain 410 g kg^?1 crude protein with fish meal, peanut meal and precoated crystalline amino acids with different concentration of l ‐leucine (16.72, 19.60, 22.06, 24.79, 27.28 and 30.16 g kg^?1 dry diet). Each diet was randomly assigned to triplicate groups of 30 shrimps (0.38 ± 0.002 g), and the feed trial lasted for 8 weeks. The results indicated that the maximum weight gain was observed at 24.95 g kg^?1 dietary leucine group, whereas the diets containing higher leucine concentration conversely reduced the growth performance (P < 0.05). Moreover, the highest body protein content and body protein deposition and the lowest haemolymph AST and ALT activities were also found at 24.95 g kg^?1 dietary leucine group. With the increase in leucine in diets, a dose‐dependent increase was found in body lipid content and haemolymph urea concentration. The polynomial regression calculated using weight gain, feed efficiency and body protein deposition indicated that the optimal dietary leucine requirement for L. vannamei reared in low‐salinity water was 23.73 g kg^?1 leucine of dry diet, correspondingly 57.88 g kg^?1 of dietary protein.     

The effect of dietary taurine supplementation on growth performance,feed utilization and taurine contents in tissues of juvenile white shrimp (Litopenaeus vannamei,Boone, 1931) fed with low‐fishmeal diets

An 8‐week feeding trial was conducted to investigate the effects of different taurine levels on the growth performance of juvenile white shrimp fed with low‐fishmeal diets. Six level diets of dietary taurine were prepared by the supplementation of taurine (0, 0.4 g kg^?1, 0.8 g kg^?1, 1.2 g kg^?1, 2.0 g kg^?1 and 4.0 g kg^?1) to a control diet (100 g kg^?1 fish meal). Each diet was randomly assigned to triplicate groups of 30 shrimps (0.48 ± 0.0 g), each three times daily. Shrimp fed the 0.4 g kg^?1 and 0.8 g kg^?1 taurine‐supplemented diets, showed significantly higher weight gain, protein efficiency ratio and protein retention efficiency than those of shrimp fed the other diets. The quadratic regression analysis (y = ?55.59x² + 187.1x + 750.2 R² = 0.587) indicated that a maximum weight gain occurring at 1.68 g kg^?1 of taurine level. The whole body and hepatopancreas taurine contents of the taurine‐supplemented diets were on the same level and higher than those of the control group. Total free amino acid content in the hepatopancreas was significantly affected by taurine supplementation. The results of the present study demonstrate that the white shrimps require taurine as an essential nutrient for growth performance.     

Use of marine by‐product meals in diets for juvenile longfin yellowtail Seriola rivoliana

A 60‐day feeding trial to determine the nutritional value of marine by‐product meals in diets for longfin yellowtail Seriola rivoliana juveniles (48.1 ± 0.6 g initial weight) was conducted. Five diets were evaluated: a reference diet (RD; 500 g kg^?1 CP, 130 g kg^?1 L), containing 500 g kg^?1 of fish meal (FM); three experimental diets with 125 g kg^?1 of shrimp head (SM), Catarina scallop viscera (CM) or Pen shell viscera (PM) meals; and one diet (SCP) containing 125 g kg^?1 of each of the experimental meals, to partially replace FM. Survival was not significantly affected by any treatment. Individual weight gain per day was high for the PM (5.3 ± 0.51 g d^?1) and SM (4.7 ± 0.32 g d^?1) diets, being significantly higher than the RD (3.5 ± 0.23 g d^?1) and the other treatments (<1.2 g d^?1). Feed intake was high in PM and SM diets, and very low in SCP and CM diets. Biochemical and haematological parameters were similar among treatments RD, PM and SM, while fish fed CM and SCP exhibited lower levels of total protein, cholesterol, haematocrit and haemoglobin. The results indicate that SM or PM can be used to partially replace FM in diets for yellowtail juveniles.     

Combined effects of dietary mannan‐ and fructo‐oligosaccharide on growth indices,body composition,intestinal bacterial flora and digestive enzymes activity of regal peacock (Aulonocara stuartgranti)

A 56‐d feeding trial was conducted to investigate the effect of dietary mannan‐oligosaccharides (MOS) and fructo‐oligosaccharide (FOS) on growth indices, body composition, intestinal bacterial community and digestive enzymes activity of regal peacock. A total of 240 fish were randomly distributed to 15 experimental units (40‐L aquariums) of 16 fish each. These replicates were randomly assigned to one of five treatments in a 2 × 2 + 1 factorial arrangement. The treatments were control diet (no MOS and FOS), diet A (2 gkg^?1 MOS + 1.5 g kg^?1 FOS), diet B (2 g kg^?1 MOS + 3 g kg^?1 FOS), diet C (4 g kg^?1 MOS + 1.5 g kg^?1 FOS) or diet D (4 g kg^?1 MOS + 3 g kg^?1 FOS). The results showed that feeding diet C increased specific growth rate and protein efficiency ratio and decreased feed conversion ratio compared with control diet. Higher intestinal trypsin activity and increased Lactobacillus counts were observed in fish fed diets B and C. All diets significantly elevated body protein deposition and intestinal amylase activity compared to the control diet. In conclusion, the diet supplemented with 4 g kg^?1 MOS + 1.5 g kg^?1 FOS was advantageous over other MOS + FOS‐supplemented diets, with respect to growth performance and health benefits of regal peacock.     

Comparative studies on dietary protein requirements of juvenile and on‐growing gibel carp (Carassius auratus gibelio) based on fishmeal‐free diets

Two trials were conducted to investigate protein requirements of juvenile (3.18 g in Trial 1) and on‐growing (87.1 g in Trial 2) gibel carp, Carassius auratus gibelio var. CAS III. Six isoenergetic diets containing 250–500 g kg^?1 dietary protein were formulated using soy protein concentrate (SPC) and casein as protein sources. The results showed that weight gain (WG) increased when dietary protein increased from 250 to 400 g kg^?1 and decreased at 400 to 500 g kg^?1 CP in Trial 1, while WG increased when dietary protein increased from 250 to 350 g kg^?1 and kept constant at 350 to 500 g kg^?1 CP in Trial 2. With increasing dietary protein, feed conversion ratio (FCR) decreased, while protein retention efficiency (PRE) decreased in Trial 1 and was not affected in Trial 2. Apparent digestibility coefficient of protein (ADC_p) increased with increasing dietary protein in two trails. Trypsin activity increased with dietary protein in the juveniles and was not affected in on‐growing fish. Hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities increased with dietary protein. Broken‐line and quadratic regression of WG estimated that dietary protein requirements for maximum growth were about 402–427 g kg^?1 for the juvenile and 337–418 g kg^?1 for on‐growing gibel carp.     

The effect of dietary methionine on growth,antioxidant capacity,innate immune response and disease resistance of juvenile yellow catfish (Pelteobagrus fulvidraco)

An 11‐week feeding trial was conducted to evaluate the effect of dietary methionine on the growth, antioxidant status, innate immune response and disease resistance to Aeromonas hydrophila of juvenile yellow catfish. Six isonitrogenous and isolipidic practical diets were formulated to contain different graded methionine levels ranging from 6.1 to 16.4 g kg^?1 of dry weight. The results indicated that growth performance and feed utilization were significantly influenced by the dietary methionine levels; fish fed the diet containing 6.1 g kg^?1 methionine level had lower specific growth rate, percentage weight gain (PWG), feed efficiency and protein efficiency ratio than those fed the other diets (P < 0.05). Fish fed the diet containing 16.4 g kg^?1 methionine level had lowest protein contents in whole body and muscle among all treatments. Triacylglycerols, cholesterol, aspartate aminotransferase, alanine aminotransferase and haemoglobin (Hb) in plasma or whole blood were significantly affected by dietary methionine levels. Fish fed the diet containing 6.1 g kg^?1 methionine level had higher superoxide dismutase, glutathione peroxidase activities and malondialdehyde values than those fed other diets. Fish fed diets containing 9.7 and 11.8 g kg^?1 methionine levels had higher lysozyme activity, total immune globulin, phagocytic activity and respiratory burst than those fed other diets. The lowest survival after A. hydrophila challenge was observed in fish fed a diet containing 6.1 g kg^?1 methionine. Quadratic regression analysis of PWG against dietary methionine levels indicated that the optimal dietary methionine requirement for the maximum growth of juvenile yellow catfish was estimated to be 11.5 g kg^?1 of the diet in the presence of 4.0 g kg^?1 cystine (corresponding to 23.5 g kg^?1 of dietary protein on a dry weight basis).     

Effects of dietary protein and lipid levels on growth,feed utilization and body composition in Pseudobagrus ussuriensis fingerlings

An 8‐week feeding trial was conducted to investigate the optimum dietary protein and lipid levels for growth, feed utilization and body composition of Pseudobagrus ussuriensis fingerlings (initial weight: 3.40 ± 0.01 g). Twelve diets containing four protein levels (350, 400, 450 and 500 g kg^?1 crude protein) and three lipid levels (50, 100 and 150 g kg^?1 crude lipid) were formulated. Fish were randomly allotted to 36 aquaria (1.0 × 0.5 × 0.8 m) with 25 fish to each glass aquarium. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. The results showed that weight gain and specific growth rate (SGR) decreased with increasing dietary lipid level from 50 to 150 g kg^?1 at the same dietary protein level. Fish fed the diets containing 150 g kg^?1 lipid exhibited higher feed conversion ratio (P < 0.05), lower protein efficiency ratio (PER) and nitrogen retention efficiency (NRE) relative to fish fed the diet containing 50 and 100 g kg^?1 lipid. Weight gain and SGR significantly increased with increasing dietary protein from 350 to 450 g kg^?1 at the same dietary lipid level, and even a little decline in growth with the further increase in dietary protein to 500 g kg^?1. Daily feed intake, NRE and PER were significantly affected by both dietary protein and lipid levels (P < 0.05) and tended to decrease with increasing dietary protein and lipid levels. Whole‐body protein content increased as protein levels increased and lipid levels decreased. Whole‐body lipid and muscle lipid content increased with increasing dietary lipid level, and decreased with increasing dietary protein at each lipid level. There was no significant difference in condition factor and viscerosomatic index among fish fed the diets. Hepatosomatic index was affected by dietary lipid level (P < 0.05), and increased with increasing dietary lipid level at the same protein level. These results suggest that the diet containing 450 g kg^?1 protein and 50 g kg^?1 lipid with a P/E ratio of 29.1 mg protein kJ^?1 is optimal for growth and feed utilization of P. ussuriensis fingerlings under the experimental conditions used in the study.     

Growth performance and TOR pathway gene expression of juvenile blunt snout bream,Megalobrama amblycephala,fed with diets replacing fish meal with cottonseed meal

A 16‐week feeding trial was conducted to assess the effects of replacing fish meal (FM) with cottonseed meal (CM) on the growth performance, feed utilization, plasma biochemical composition and target of rapamycin (TOR) pathway gene expression of juvenile blunt snout bream (Megalobrama amblycephala). Five isonitrogenous (36% crude protein) and isoenergetic (16 MJ kg^?1) diets with graded replacing levels of CM (replacing 0, 25, 50, 75 and 100% FM with CM) and similar lysine and methionine concentrations were fed to triplicate groups of fish. Results revealed that specific growth rate (SGR), feed intake and protein efficiency ratio (PER) of group fed with diets replacing FM with CM up to 50% were significantly higher than others (P < 0.05). However, final body weight and feed conversion ratio (FCR) remained similar up to 25% and thereafter significantly decreased and increased, respectively, as the replacement level increased (P < 0.05). Replacement levels significantly decreased hepatosomatic index and viscerosomatic index (P < 0.05), but did not significantly affect condition factor and whole body compositions. Free gossypol mainly accumulated in liver and significantly increased in diets CM75 and CM100 than CM0 (P < 0.05). Replacement significantly influenced plasma urea contents (P < 0.05). Meanwhile, increasing replacement of FM with CM in diets increased insulin‐like growth factor I (IGF‐1) gene expression in liver of blunt snout bream. Target of rapamycin (TOR) gene expression in diet CM100 was significantly lower than that in diets CM0 and CM75, while the eukaryotic translation initiation factor 4E‐binding protein 2 (4E‐BP2) gene expression was not affected by the replacement level of CM in diets. Therefore, based on final body weight and FCR, it suggested that up to 25% of FM (150 g kg^?1 in basal diet) could be replaced by CM in diets, which was 112.5 g kg^?1 FM and 192.9 g kg^?1 CM, for juvenile blunt snout bream.     

Effects of dietary microbial levan on growth performance,RNA/DNA ratio and some physio‐biochemical responses of Labeo rohita (Hamilton) juveniles

Six isonitrogenous and isocaloric semi‐purified diets were prepared with different levels of microbial levan: control (Basal), T1 (Basal + 2.5 g kg^?1 diet), T2 (Basal + 5 g kg^?1 diet), T3 (Basal + 7.5 g kg^?1 diet), T4 (Basal + 10 g kg^?1 diet) and T5 (Basal + 12.5 g kg^?1 diet), fed to six groups of fish in triplicate tanks. The results of the 60 days feeding trail showed that supplementation of dietary levan significantly affected the weight gain percentage and specific growth rate of the treatment groups fed at 10 g kg^?1 or more levan. Lowest feed conversion ratio (FCR) value and highest survival percentage among levan fed groups were observed with 12.5 g kg^?1 incorporation (T5) and was comparable with (T4) group. Significant increase in muscle RNA level and RNA/DNA ratio was observed with the increasing dietary levan. Fish fed 12.5 g kg^?1 levan had significantly higher protease, amylase and lipase activities compare with the control group. Lowest Aspartate aminotransferase (AST) activity in the liver and muscle was observed in the T5 group fed with highest level of dietary levan. Overall results conclude that dietary microbial levan incorporation at 12.5 g kg^?1 could be used as potent dietary prebiotic for the culture of L. rohita juveniles.     

Digestibility of Glandless Cottonseed Protein in Diets for Pacific White Shrimp,Litopenaeus vannamei

Accurate digestibility coefficients for protein, energy, and lipid are needed by feed formulators to optimize diets to meet nutritional requirements and to substitute ingredients cost‐effectively. Of particular interest is protein, which accounts for the majority of shrimp feed content and expense. The current study evaluated seven cottonseed meal and protein products. Most of the samples were derived from a glandless cotton variety that lacks significant levels of the antinutritive compound, gossypol. The various protein fractions were evaluated for apparent crude protein, crude lipid, and energy digestibility when fed to juvenile Pacific White Shrimp, Litopenaeus vannamei. Apparent energy digestibility for the protein fractions derived from the glandless seed ranged from 76.7% for ground kernels to 94.6% for protein isolate, and these values were greater than the value obtained for the commercial meal that contained gossypol (64%). Apparent protein digestibility for the six glandless‐cotton‐based samples varied from 72.3% for the ground full‐fat kernels to 94.1% for the protein isolate, and these values were mostly higher than the value obtained for the commercial meal (82.3%). The high apparent digestibility values demonstrate that low‐gossypol cottonseed protein products may be useful as a cost‐effective replacement for more expensive protein sources in L. vannamei diets.     

Effective use of glucose rather than starch in formulated semimoist diets of common octopus (Octopus vulgaris)

The aim of the present work was to test the capacity of Octopus vulgaris to use carbohydrates supplied in three diets: a diet without added carbohydrates (diet C0: 500 g kg^?1 water, 200 g kg^?1 gelatine, 100 g kg^?1 egg yolk powder, 50 g kg^?1 freeze‐dried Sardinella aurita and 150 g kg^?1 freeze‐dried Todarodes sagittatus) and two obtained by substituting 50 g kg^?1 of T. sagittatus by glucose (diet GLU50) or by starch (diet STA50). The most stable and best‐accepted diet was STA50 (SFR 1.26%BW day^?1) although there were no significant differences in the growth rates obtained with the three diets: 10.12 g day^?1, 9.37 g day^?1 and 11.22 g day^?1 for C0, GLU50 and STA50, respectively (P > 0.05). The feed efficiency indices were better for GLU50, of particular note being the protein productive value of 71.88% and a feed conversion ratio lower than 1. Protein and lipid digestibility were similar in all the three diets (96–98% for proteins and 85–94% for lipids), whereas carbohydrate digestibility was higher in GLU50 (98%) than in C0 (84%) and STA50 (0.33%). The content of carbohydrates increased in muscle and the digestive gland as a consequence of the increased carbohydrates intake.     

Effects of DL‐methionine supplementation on the success of fish meal replacement by plant proteins in practical diets for juvenile gibel carp (Carassius auratus gibelio)

A ten‐week feeding trail was conducted to investigate the effects of increasing DL‐methionine (Met) supplementation on the success of fish meal (FM) replacement with plant proteins in practical diets for juvenile gibel carp, Carassius auratus gibelio. Twelve isoenergetic diets were formulated including two 150 g kg^?1 FM diets (Diet 1—positive control 1 reflecting a commercial diet and Diet 2—positive control 2 reflecting a commercial diet but with balanced essential amino acid (EAA) profile) and ten 50 g kg^?1 FM diets (negative controls) supplemented with graded levels (0–3.0 g kg^?1) of DL‐Met (Diets 3–12). Each diet was fed to triplicate groups of gibel carp, near satiation four times daily for 10 weeks. Diet 2 with balanced EAA profile produced better final weight, specific growth rate (SGR) and feed conversion ratio (FCR) than the negative control diet containing no supplemental Met (Diet 3), but did not significantly differ from Diet 1. However, DL‐Met supplementation (0.5–3.0 g kg^?1) in the negative control diets (Diets 4–12) produced growth performances similar to those fed the positive control diets (Diets 1 and 2). Based on quadratic regression analysis, the optimal dietary Met level with 5.2 g kg^?1 of dietary cysteine (Cys) was found to be 7.1 g kg^?1 dry diet for SGR and FCR. The corresponding total sulphur amino acid requirements (Met + Cys) of this species were calculated to be 12.3 g kg^?1 dry diet for SGR and FCR. DL‐Met supplementation in 50 g kg^?1 FM diets showed a decreasing trend in plasma cholesterol contents (p < .05). No significant differences were observed in whole‐body composition, plasma protein, triglyceride and free EAA contents among dietary treatments, while plasma aspartate transaminase, albumin and ammonia contents were significantly influenced by dietary Met levels. Juvenile gibel carp grew equally well on 150 g kg^?1 FM diet or 50 g kg^?1 FM diets balanced for EAA profile with supplemental amino acids. The results of this study overall indicate that balancing dietary amino acid levels with DL‐Met supplementation is a key strategy in successfully reducing FM levels in the diets of gibel carp.     

The effects of dietary lipid levels on performance and heat‐shock protein response of juvenile white seabass,Atractoscion nobilis

A feeding trial was conducted to study the effect of dietary lipid on growth performance and heat‐shock protein (HSP70 and HSP60) response of white seabass (WSB), Atractoscion nobilis. Five diets were formulated to contain 440 g kg^?1 protein from 300 g kg^?1 fish meal, 240 g kg^?1 soybean meal and 100 g kg^?1 soy protein concentrate with different levels of lipid: 100, 120, 140, 160 or 180 g kg^?1. At the end of the trial, heat shock response based on HSP70 and HSP60 was measured in liver and white muscle from fish at ambient temperature and temperature shock conditions. Final weight and percent gain were significantly higher for fish fed the 100 g kg^?1 lipid diet than for fish fed the rest of the diets (P ≤ 0.05). Feed conversion ratio was lowest for fish fed the 100 g kg^?1 lipid diet. The HSP70 and HSP60 responses were positively correlated to dietary lipid levels following temperature shock. At ambient temperature, HSP60 and HSP70 responses in muscle and HSP60 response in liver increased with dietary lipid level. Temperature shock significantly increased the HSP response of fish in all treatments. Results of this study demonstrated that a moderate (110–120 g kg^?1) level of dietary lipids would be recommended for production diets but a higher dietary lipid level may be required for optimal stress tolerance.