Lower Protein Efficiency Ratio Research Articles

Impact of feed availability on growth performance and amino acid utilization of cobia (Rachycentron canadum) at elevated temperature

IntroductionThis study explored the effects of increased water temperatures and limited feeding on the growth, feed utilization, and nutrient retention in juvenile cobia (Rachycentron canadum).MethodsJuvenile cobia, approximately 5.0 g in body weight, were distributed across two temperature conditions: 34°C, to mimic a global warming scenario, and 30°C, the current local summer average, as controls. The setup included eighteen 200-liter tanks, with 20 fish per tank. Within each temperature regime, triplicate tanks received one of three feeding levels (55%, 75%, and 95% of satiation as determined at 30°C) over a six-week period.ResultsThe findings indicated that cobia exhibited the poorest growth performance at the elevated temperature (34°C) and the lowest feeding level (55%). These conditions also correlated with the lowest protein efficiency ratio and feed intake. The feed conversion ratio worsened with increased temperature and feeding levels, while protein production values decreased at higher temperatures. A lower feeding level caused a lower total lipid retention but led to increased retention of whole body essential amino acids.DiscussionAfter six weeks, a 24-hour post-prandial analysis showed selective retention of some amino acids in muscle and plasma, but significantly higher retention in the liver at the higher temperature. Only a few amino acids' retention was influenced by feeding level. These results suggest that temperature and feeding levels alter the prioritization of amino acid metabolism and retention, as well as the utilization of energy and substrates across different organs of the cobia.

The American cockroach (Periplaneta americana) residue could partially replace the dietary fish meal in the juvenile Nile tilapia (Oreochromis niloticus)

The American cockroach (Periplaneta americana) residue is a by-product of P. americana meal after extracting active ingredients with ethanol, and it still contains high protein, lipid, and a certain amount of active ingredients, may be a potential fish meal alternative. Five isonitrogenous and isolipidic experimental diets were formulated to replace 0%, 25%, 50%, 75%, and 100% of dietary fish meal with P. americana residue, and defined as Diet 1, Diet 2, Diet 3, Diet 4, and Diet 5, respectively. The juvenile Nile tilapia (Oreochromis niloticus) with an initial body weight of 2.98 ± 0.01 g was fed with respective diets for 10 weeks, which was conducted to investigate the effects of dietary fish meal replacement by P. americana residue on the growth performance, proximate composition, amino acid profile, metabolism, antioxidant capacity, and immunity of juvenile O. niloticus. There were no significant differences in the final body weight, weight gain rate, and specific growth rate among five diet groups, while the highest feed conversion ratio and the lowest protein efficiency ratio were recorded in Diet 4. There were no significant differences in the contents of crude protein, total lipid, ash, and total amino acid in the whole fish body among all groups. The Diet 1 and Diet 2 had higher activities of trypsin, α-amylase, and chitinase in the intestine and α-amylase in the liver. The highest serum urea content was detected in Diet 4, while the lowest liver urea content and the highest serum total protein content were detected in Diet 3. A higher liver catalase, glutathione peroxidase, and serum lysozyme activities were detected in Diet 2, and the lowest serum malondialdehyde content was detected in Diet 2. In conclusion, dietary fish meal replacement by the P. americana residue had no negative effects on the growth performance and body composition of juvenile O. niloticus, and significantly improved the antioxidant capacity and immunity, while feed utilization rate was reduced when dietary fish meal replacement levels exceeded 75%.

Interaction between dietary selenium and methylmercury on growth performance, deposition and health parameters in rainbow trout fed selenium-rich tuna-based diets or selenium-poor plant-based diets

This study evaluated the effect of dietary mercury (Hg) and selenium (Se) sources and levels on growth performance, Hg and Se accumulation, pro-inflammatory cytokine levels and global health parameters in rainbow trout juveniles. A 6-month feeding trial was carried out with a control plant-based diet (containing analyzed Se and Hg levels: 0.3 and 0 mg/kg diet, respectively) or a control tuna-based diet (containing analyzed Se and Hg levels: 7.5 and 0.3 mg/kg diet, respectively) supplemented with 0 or 1.5 mg Se/kg diet supplied either as sodium selenite (Se(IV)) or selenomethionine (SeMet) combined with 0, 1.6 or 2 mg Hg/kg diet supplied as methylmercury (MeHg). Fish sampling was carried out at 2 times: after a short (21 days) and a long term dietary exposure (168 days). In the short term, a temporarily reduced growth was noticed in fish fed MeHg-supplemented plant-based diet in absence of dietary Se supplementation. MeHg supplementation increased pro-inflammatory cytokine TNF-α and IL-1β levels in plant and tuna-based diets. MeHg supplementation also affected short-term fish global health parameters with an increase of glucose and albumin levels in tuna-based diets. The addition of SeMet in MeHg-supplemented tuna-based diets protected against the increase of TNF-α level in the long term whereas the addition of Se(IV) in MeHg-supplemented tuna-based diets decreased whole-body Hg level and retention in the short term. In the long term, a reduced growth, a higher feed conversion ratio and a lower protein efficiency ratio were recorded in fish fed Se(IV)-supplemented tuna-based diets in absence of MeHg supplementation. The addition of Se(IV) or SeMet in tuna-based diets increased plasma IL-6 level. The addition of MeHg in plant and tuna-based diets increased Se accumulation and retention. This work underlines that different forms of Se supplementation, in two dietary background context (low basal Se level in plant-based diets and high basal Se level in tuna-based diets), have specific effects on metabolism and biological consequences of dietary MeHg. Dietary inorganic Se (but not organic Se) affected MeHg metabolism by reducing Hg accumulation in fish. However, dietary organic Se displayed better ability to afford protection against MeHg pro-inflammatory effects.

Dietary protein requirement of juvenile spotted knifejaw Oplegnathus punctatus

A dietary strategy was conducted with graded crude protein (CP) levels (various from 27.08% to 58.10%) in six semi-purified diets to investigate the appropriate dietary CP supplement for juvenile spotted knifejaw (Oplegnathus punctatus). Experimental diets were respectively offered to the juvenile fish with three replicates (18 individuals each replicate, 19.91 g fish-1) for 8-week. After the feeding trial, the weight gain (WG) was improved by increment of dietary CP levels, but deteriorated slightly when dietary CP over 45.87%. The daily feed intake (DFI) elevated as dietary CP decreasing. Besides, the lowest protein efficiency ratio (PER) and feed efficiency (FE) were observed in 27.08% CP treatment. However, the PER and energy retention (ER) were not significantly different among 32.97%, 39.71% and 45.87% CP groups. In the current study, fish fed diet with 58.10% CP obtained slightly lower PER and nitrogen retention (NR), but relatively higher lipid retention (LR) value compared to those fed a diet with 45.87% CP. And the daily nitrogen intake (DNI) in the fish fed on the low CP levels (27.08 to 39.71%) were significantly lower than that in 45.87% CP treatment. The various dietary treatments did not differ in the visceral index (VSI), hepatosomatic index (HSI) and serum glucose, but fish in the lowest CP group had a decreased intraperitoneal fat ratio (IPF). The protein content in the whole body and dorsal muscle of the fish significantly elevated with dietary protein increasing. The aspartate transaminase (AST) in serum increased with increasing dietary CP from 27.08%-52.65 and then decreased. The regression analysis in second order polynomial and two slope broken-line mode based on NR and WG indicated that the optimal protein supplement for juvenile O. punctatus is 42.92%-46.44%. The present study also indicated that O. punctatus had poor ability to utilization dietary carbohydrate.

An evaluation of the growth, blood biochemistry, hepatic glucose metabolism and hepatocyte apoptosis in the genetically improved farmed tilapia Oreochromis niloticus fed diets with distinct protein to corn starch ratios

This study was performed to evaluate the effects of dietary distinct protein to starch ratios on the growth, feed utilization, blood biochemistry, hepatic glucose metabolism and hepatocyte apoptosis of Nile tilapia Oreochromis niloticus. Three iso-lipidic (ca 6.56%) diets were formulated with elevated corn starch levels at the cost of protein provision, being designated as diets P40S5 (40.4% protein and 4.62% starch), P30S25 (30.4% protein and 24.2% starch) and P20S50 (19.9% protein and 48.6% starch). Tilapia juveniles (initial mean body weight, 32.0 g/fish) were assigned to 12 rectangular tanks (250 L each) with 20 fish per tank and fed the experimental diets to apparent satiation for 8 weeks. The results showed that either excess (40%) or insufficient (20%) amount of dietary protein impaired the growth of tilapia. Excess dietary protein led to unsatisfactory protein catabolism (lower protein efficiency ratio and protein productive value, and higher mRNA levels of hepatic glutamic-pyruvic transaminase 1 and glutamic-oxaloacetic transaminase paralogs), while insufficient amount of protein resulted in lower whole-body protein percentage. An increase in dietary starch from 5% or 25% to 50% was associated with enhanced lipid and glycogen storages in the liver of tilapia. Consistently, dietary starch reception up to 50% upregulated the expression of hepatic representative genes involved with glycolysis (glucokinase and phosphofructokinase muscle type a) and lipogenesis (acetyl-CoA carboxylase α and fatty acid synthase) while downregulated the expression of the gluconeogenic glucose-6-phosphatase catalytic subunit paralogs. TUNEL staining suggested that stronger apoptosis signal was recorded at the bile duct epithelium of the P20S50 fish. Concomitantly, plasma bile acid level nearly doubled, and an incidence (50%) of ‘green liver’ was observed in this treatment as compared with the P40S5 and P30S25 fish, indicating that bile acid metabolism disorder might be induced. Though plasma glucose (4.66–5.11 mmol/L) was not responsive to different treatments, advanced glycation end-products accumulated in the blood of the P20S50 fish, suggesting that 50% starch reception was probably associated with the progression of diabetes-associated pathologies. The overall results in this study suggested that tilapia might possess capability to tolerate dietary corn starch level up to 50% in a short-term exposure, whereas a long-term exposure might induce detrimental effects on liver functions.

The feasibility of partial replacement fish meal with poultry by‐products in practical diets of juvenile great sturgeon, Huso huso : Effects on growth performance, body composition, physiometabolic indices, digestibility and digestive enzymes

To characterize the effects of a poultry by-product (PBM) on the gonadosomatic, physiometabolic indices, digestibility and digestive enzymes of juvenile Huso huso (28.42 ± 0.17 g), we procured six experimental diets with 0 (control), 20%, 40%, 60%, 80% and 100% PBM to replace fishmeal. After an 8-week feeding trial, results confirmed that the weight gain, the specific growth rate of fish fed the 80% and 100% diets were markedly inferior to other groups (p < 0.05). Also, the highest feed conversion ratio and the lowest protein efficiency ratio were observed in dietary of full replacement of fishmeal by PBM (p < 0.05). Triglyceride and cholesterol significantly increased in the PBM100 than the control and PBM20 (p < 0.05). Gastrointestinal enzyme activities were notably decreased in fish fed the diets of more than 60% substitution of fishmeal by PBM (p < 0.05). No statistical difference was observed in the digestibility of protein, dry matter, lipid and gross energy in fish fed up to 300 g/kg (PBM60) of PBM, while beyond this level, all of ADCs value reduced (p < 0.05). Taken together, the optimum range replacement by PBM was 235.9–251.8 g/kg in juvenile Huso huso diet based on the broken-line regression analysis.

The effects of high‐macronutrient (protein, fat and carbohydrate) diets on growth performance and muscular metabolic responses in grass carp

Four purified diets were fed to quadruplicate groups of grass carp (Ctenopharyngodon idella) (initial body weight 55 g; 20 fish per replicate) for 11 weeks. The gross energy of three high-macronutrient diets was 11% higher than that of the control diet. The high-protein diet led to the highest weight gain (WG) and specific growth rate (SGR), while the lowest protein efficiency ratio (PER) and protein retention efficiency (PRE) (p < .05). No significant effect on the above four indexes was observed in fish fed the high-fat diet (p > .05). Fish fed high-carbohydrate diet had the lowest WG and SGR (p < .05), while no significant difference was found in PER and PRE (p > .05). The contents of crude fat, total polyunsaturated fatty acids in muscle in high-fat and high-carbohydrate groups, but not in high-protein group, were significantly higher than those of control group (p < .05). The contents of muscular protein and most amino acids did not show any clear change in response to high-macronutrient diet (p > .05). Gene expression data in muscle indicated that g6pd, fas and acc1 in muscle were up-regulated in high-fat and high-carbohydrate groups, and fbp and pck were significantly up-regulated in high-macronutrient groups (p < .05). In conclusion, the high-fat and high-carbohydrate diets increased muscular fat deposition by up-regulation the key enzymes expressions of pentose phosphate pathway and fat synthesis, and high-macronutrient diets increased muscular glycogen content by up-regulation gluconeogenesis enzymes expressions.

Partial substitution of fish meal with soy protein concentrate in commercial diets for juvenile swimming crab, Portunus trituberculatus

A 56-day feeding trial was conducted to evaluate the potential use of soy protein concentrate (SPC) as a partial replacement of fish meal in swimming crab Portunus trituberculatus. Four isonitrogenous and isolipidic diets (450 g/kg protein and 80 g/kg lipid) were formulated to contain graded levels of SPC, and fish meal was replaced with SPC at 25%, 50% and 75% level (SPC25, SPC50 and SPC75, respectively). The control diet (SPC0) contained fish meal, soybean meal and krill meal as the main protein sources. Lysine and methionine were added into SPC replacement diets to maintain the same concentrations as the control diet. Each diet was randomly assigned to triplicate groups of 45 juvenile swimming crabs (5.00 ± 0.23 g / crab) that were stocked in the rectangle plastic baskets. The results indicated that the weight gain (WG), special growth rate (SGR), feed efficiency (FE) and daily feed intake (DFI) were not significantly influenced by the dietary replacement of fish meal with SPC (P > 0.05). Crabs fed the SPC75 diet had lower protein efficiency ratio (PER) and molting frequencey (MF) than those fed the SPC50 diet(P < 0.05). The proximate compositions in whole body and muscle were not significantly influenced by the replacement of fish meal with SPC (P > 0.05), however, there was significant difference in the hepatopancreas moisture content (P < 0.05), and crabs fed the SPC0 diet had the highest lipid in hepatopancreas among all treatments (P < 0.05). Moreover, the essential amino acid (EAA), non-essential amino acid (NEAA) and total amino acid (TAA) contents of muscle significantly increased with the dietary replacement of fish meal with SPC levels increasing from 0 to 75% (P < 0.05). No significant differences in hemolymph enzyme activities and characteristics were observed among all treatments (P > 0.05). Crabs fed the SPC0 diet had higher amylase and lipase activities in hepatopancreas than those fed other diets. The hepatopancreas trypsin activity was not significantly influenced by the replacement of fish meal with SPC (P > 0.05). The hepatopancreas alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities increased when the dietary SPC levels increased from 0 to 25%, and then decreased significantly with the further increase of SPC replacement levels (P < 0.05). The relative expression of genes in target of rapamycin (TOR) pathway, crabs fed the SPC0 diet had higher relative expressions of tor, akt, s6k1, s6, 4ebp1, eif4e1a, eif4e2 and eif4e3 genes in hepatopancreas than those fed other diets (P < 0.05), moreover, there were no significant differences in gene expressions of TOR pathway among crabs fed the SPC25, SPC50 and SPC75 diets (P > 0.05). Based on the two slope broken-line regression analysis of PER against the dietary fish meal replacement with SPC levels, the optimum dietary replacement of fish meal with SPC was determined to be 51.49% for juvenile swimming crab.

Effects of dietary manganese source and supplemental levels on growth performance, antioxidant enzymes activities, tissue Mn concentrations and cytosolic manganese superoxide dismutase (cMnSOD) mRNA expression level of juvenile Litopenaeus vannamei

This experiment was conducted to study the effects of different forms and levels of manganese (Mn) on the growth performance, antioxidant activities, tissue Mn content and cytosolic manganese superoxide dismutase (cMnSOD) gene expression of Litopenaeus vannamei. Treatments consisted of 0, 10, 20, 30, 40 and 60 mg Mn kg−1 from manganese sulphate (Mn-S) and manganese methionine (Mn-Met), providing the actual dietary value of 5.17, 15.62, 25.55, 34.22, 44.48 and 67.90 mg Mn kg−1 Mn-S, and 5.17, 15.71, 25.36, 35.86, 45.16 and 65.06 mg Mn kg−1 Mn-Met, respectively. Each diet was fed to triplicate groups of L. vannamei (initial body weight: 1.925 ± 0.002 g) in a recirculated fresh water rearing system for 8 weeks. Weight gain rate (WGR) increased in prawns provided with from 25.55 to 44.48 mg Mn kg−1 Mn-S and 15.71 to 45.16 mg Mn kg−1 Mn-Met and then declined above these levels. The lowest protein efficiency ratio (PER) and the highest feed conversion rate (FCR) were observed in prawns fed the control diet (P 0.05). Survival rate (SR) was not affected by the dietary treatments (P > 0.05). Total SOD and Mn-SOD activities were higher in the hepatopancreas of prawns fed with Mn-supplemented diets from 15.71 to 44.48 mg Mn kg−1 (P < 0.05). On the contrary, malondialdehyde (MDA) content was lower in the hepatopancreas of prawns fed the basal diet (P < 0.05). Mn concentrations in the hepatopancreas and muscles increased with increasing levels of dietary Mn supplementation. Moreover, Mn accumulation was lower in the muscle than in the hepatopancreas of the prawns. The mRNA expression of cMnSOD gene in the hepatopancreas of prawns was upregulated with increasing dietary Mn levels of Mn-S from 25.55 to 44.48 mg Mn kg−1, Mn-Met from 15.71 to 45.16 mg Mn kg−1 and then plateaued above these levels. Broken-line regression analysis of WGR indicated that the optimal dietary Mn requirements for juvenile L. vannamei were 32.26 mg Mn kg−1 Mn-S and 23.90 mg Mn kg−1 Mn-Met, respectively.

Effects of dietary glucose and starch levels on the growth, haematological indices and hepatic hexokinase and glucokinase mRNA expression of juvenile mirror carp (Cyprinus carpio)

The effect of the different dietary carbohydrate types and levels on growth performance, haematological indices and hepatic hexokinase (HK) and glucokinase (GK) genes expression involved in control of glucose metabolism, was studied in juvenile mirror carp (Cyprinus carpio). Two carbohydrates (glucose and starch) diets with two levels (250 and 500 g kg−1) were fed to triplicate groups of 35 fish for 60 days. The best weight gain rate and specific growth rate were observed in fish fed with 250 g kg−1 glucose diet and 500 g kg−1 starch diet (P < 0.05). Fish fed with 500 g kg−1 glucose showed low feed utilization, with the highest food conversion ratio and the lowest protein efficiency ratio (P < 0.05). Hepatosomatic index was significantly higher in fish fed with glucose diets and the 500 g kg−1 starch diet compared to 250 g kg−1 starch. CHOL, HDL-C and LDL-C were significantly highest in fish fed with 500 g kg−1 starch than all other diets (P < 0.05). Hepatic GK mRNA expression level and activity were positively related to glucose and starch levels (P < 0.05). Correlation analysis showed that hepatic glycogen concentration was increased by dietary carbohydrate content (P < 0.05). These results suggest that GK may play a major role in the postprandial glucose utilization in juvenile mirror carp.

Growth performance and quality characteristics of flaxseed-fed broiler chicks

A 42-day study was conducted to evaluate the effect of ground full-fat flaxseed supplementation on growth performance, carcass characteristics, α-linolenic acid (ALA), linoleic acid (LA) and organoleptic characteristics of broiler meat. A total of 200 one-day-old broiler chicks were randomly allocated to five experimental groups and were fed isoenergetic and isonitrogenous diets containing flaxseed at 0%, 2.5%, 5.0%, 7.5% and 10%. Flaxseed supplementation did not affect the weekly body weight of broiler chicks during the first three weeks, but thereafter it reduced significantly with increasing levels of flaxseed in the diets. Birds fed on 10% flaxseed showed a reduction of 10.08% in body weight as compared to the control group. Diets containing 5.0–7.5% flaxseed resulted in significantly lower weight gain, higher feed conversion ratio, energy efficiency ratio and lower protein efficiency ratio as compared to control and 2.5% flaxseed diets. The carcass characteristics data indicated a little variation in the evisceration rate and giblet among treatment groups, but the breast yield was significantly higher in control than flaxseed groups. The protein, fat and ash content of broiler meat were not affected with the level of flaxseed in the diets. However, the inclusion of flaxseed in the diets significantly increased the ALA in the breast and thigh tissues with no difference in the organoleptic quality of meat.

Effects of dietary lipid levels on growth, feed utilization, body composition and antioxidants of juvenile mud crab Scylla paramamosain (Estampador)

This study was carried out to determine the effects of dietary lipid levels on growth performance, feed utilization, body composition and antioxidant parameters of juvenile mud crab ( Scylla paramamosain ). Five isonitrogenic and isoenergetic experimental diets (45% crude protein) containing 0%, 3%, 6%, 9% and 12% added oils (named L0, L3, L6, L9 and L12, respectively) were fed to triplicate groups of 20 crabs (initial weight 11.53 ± 0.52 g, carapace width 3.92 ± 0.14 cm) for 8 weeks. The results showed that the survival, final body weight, carapace width, specific growth rate and molting frequency of crabs fed diet L6 were significantly higher than those of crabs fed diet L0, L3 or L12 ( P < 0.05). The highest feed conversion ratio and the lowest protein efficiency ratio were both observed in crabs fed diet L0 ( P < 0.05). The maximum voluntary feed intake was found in crabs fed diet L3 ( P < 0.05). The lipid contents of whole body and hepatopancreas increased remarkably with the elevated dietary lipid levels ( P < 0.05). The proportions of saturated fatty acid and monounsaturated fatty acid of the hepatopancreas were significantly higher in crabs fed diet L0 ( P < 0.05). The fatty acid composition of the hepatopancreas and muscle was consistent with those in the diets. In the hepatopancreas, crabs fed diet L12 accumulated the highest concentration of malondialdehyde than other groups ( P < 0.05), and the activities of antioxidant enzymes (superoxide dismutase, glutathione S-transferase and glutathione peroxidases) were all enhanced with the increased dietary lipid levels ( P < 0.05). The results suggested that a proper dietary lipid level of 8.52%–11.63% (optimum 9.5%) could maintain solid growth performance and antioxidant capacity of juvenile mud crab S. paramamosain . • We evaluate the effects of the diets with different lipid levels of juvenile mud crab. • The crabs cultured individually in a recirculation aquaculture system • The proper dietary lipid levels (8.52%–11.63%) could be suitable for juvenile mud crab. • The optimum dietary lipid requirement was approximate to 9.5%.

Growth, feed utilization and body composition of juvenile Manchurian trout,Brachymystax lenok(Pallas) fed different dietary protein and lipid levels

A 10-week feeding trial with four dietary protein levels (400, 450, 500 and 550 g kg−1 crude protein) and two dietary lipid levels (80 and 160 g kg−1 crude lipid) was conducted to assess optimum dietary protein and lipid levels for the growth, feed utilization and body composition of juvenile Manchurian trout (initial weight 11.80 ± 0.15 g). Fish were fed twice daily (08:30 and 16:30 h) to apparent satiation. The results showed that fish fed the diet with 500 g kg−1 protein and 80 g kg−1 lipid had the highest growth and feed efficiency. However, fish fed the diet with 450 g kg−1 protein and 160 g kg−1 lipid showed comparable growth to that of the fish fed diet 5 (500/80) and had higher protein efficiency ratio (PER), nitrogen retention (NR) and energy retention (ER) than other groups (P < 0.05). Growth, PER, NR and ER of fish fed the 160 g kg−1 lipid diet was significantly higher (P < 0.05) than that of fish fed the 80 g kg−1 lipid diet at 400 and 450 g kg−1 protein diet, whereas these values showed an opposite trend at 500 and 550 g kg−1 protein diet, and the lowest PER, NR and ER was found by fish fed the 400 g kg−1 protein diet with 80 g kg−1 lipid. Fish fed diets with 400 g kg−1 protein had lower feed intake (FI) than that of other groups. Feed intake of fish fed 80 g kg−1 lipid level was significantly lower than that of fish fed 160 g kg−1 lipid diet at 400 g kg−1 protein (P < 0.05), while no significant differences were observed at 450, 500 and 550 g kg−1 protein-based diets. Contrary to moisture content, lipid content of whole body and muscle increased significantly (P < 0.05) with increasing lipid levels. The results of this study indicated that the diet containing 450 g kg−1 protein and 160 g kg−1 lipid, with a P/E ratio of 23.68 g protein MJ−1 would be suitable for better growth and feed utilization of juvenile Manchurian trout under the experimental conditions and design level used in this study.

Effects of dietary carbohydrate level on growth and body composition of juvenile giant croakerNibea japonica

An 8-week feeding trial was conducted to investigate the effect of dietary carbohydrate level on the growth performance, body composition of giant croaker, Nibea japonica. The six diets were designated as carbohydrate level from 0% to 30%. Each diet was fed to triplicate groups of 18 giant croaker (initially weighing, 7.40 ± 0.15 g fish−1) in flow-through sea water system. The weight gain (WG) and special growth ratio (SGR) had tendency to increase with carbohydrate level from 0% to 12% after that decreased, and significantly lower in fish fed diet with 30% carbohydrate level than in other groups. Moreover, fish fed diet with 30% dietary carbohydrate has significantly higher feed conversion ratio (1.48 ± 0.18) and lower protein efficiency ratio (1.69 ± 0.21) than other groups (P < 0.05). The intraperitoneal fat ratio and condition factor had no significant difference in different groups (P > 0.05), hepatosomatic index value increased with dietary carbohydrate increased (P < 0.05). The result of this study also suggested that excess carbohydrate level (30%) led to lower lipid content in whole body. Based on the second-order polynomial regression analysis of WG and SGR, 12.2–12.7% dietary carbohydrate provided maximum growth of N. japonica.

Effects of Dietary Lipid Level on Growth and Feed Utilisation of Gilthead Seabream (Sparus Aurata L.) Reared at Mediterranean Summer Temperature

We investigated the effects of different dietary lipid levels on gilthead seabream, Sparus aurata, reared at Mediterranean summer temperature. Sixty fish (average weight 75 g) per tank were randomly distributed, in triplicate groups, in a recirculating rearing system (27±1°C) and fed ad libitum five isonitrogenous (46% dietary protein) diets with increasing lipid level (16, 18, 20, 22 and 24% named D16, D18, D20, D22 and D24, respectively), over 89 days. Specific growth rate and final body weight were not affected by dietary lipid levels. Feed conversion ratio was significantly higher (P≤0.05) in D16 as compared to the other treatments, most likely due to the shortage of dietary energy supply, coped with a significantly higher voluntary feed intake. Consequently, we obtained a significantly lower protein efficiency ratio and gross protein efficiency in D16. Gross lipid efficiency was significantly higher in D16 and D18 than in the other treatments. Biometric parameters and lipase activity in gut content were not influenced by dietary treatments. In conclusion, D18 seems the most suitable diet for gilthead seabream reared at Mediterranean summer temperature, providing both the lowest fish in fish out (FIFO) ratio and a protein sparing effect, which makes gilthead seabream’s production economically and environmentally more sustainable.

Microarray Analysis of Hepatic Gene Expression in Juvenile Japanese Flounder Paralichthys olivaceus Fed Diets Supplemented with Fish or Vegetable Oils

Gene expression profiling was performed in Japanese flounder Paralichthys olivaceus fed diets supplemented with fish oil (FO), linseed oil (LO), or olive oil (OO) for 6weeks. The LO and OO groups showed significantly retarded growth, lower feed intake, lower protein efficiency ratio, and lower hepatosomatic index (P < 0.05). Liver fatty acid composition reflected the dietary fatty acid composition. Microarray analysis revealed that dietary n - 3 highly unsaturated fatty acid (HUFA) deficiency affected 169 transcripts. In the LO group, 57 genes were up-regulated and 38 genes were down-regulated, whereas in the OO group nine genes were up-regulated and 87 genes were down-regulated. Analysis of the functional annotations suggested that dietary n - 3 HUFA affected genes involved in signal transduction (23.2%), cellular processes (21.1%), metabolism (including glucose, lipid, and nucleobase; 15.5%), transport (11.3%), regulation of transcription (10.5%), and immune response (4.2%). Several genes encoding serine/threonine kinases such as protein kinase C and calmodulin-dependent kinase and nuclear hormone receptors such as vitamin D receptor, retinoic acid receptor, and receptors for cytokines (bone morphogenic protein and transforming growth factor β) were affected. Among 169 transcripts, 22 genes were affected in both LO and OO groups. The present study identified several genes involved in n - 3 HUFA deficiency-sensitive pathways, which will be useful for selective breeding of flounder strains able to adapt to n - 3 HUFA deficiency.

배합사료의 크기, 공급횟수 그리고 사육밀도가 조피볼락(Sebastes schlegelii) 치어의 성장에 미치는 영향

We performed four sets of feeding trials to establish optimum feed size (Exp-I), stocking density (Exp-II) and feeding frequency (Exp-III and IV) for Korean rockfish. In Exp-I, three different particle sizes of a commercial diet (small, 2.0-2.1 mm; medium, 2.4-3.2 mm; and large, 4.0-5.3 mm) were fed to four replicate groups of fish (<TEX>$22.8{\pm}0.1g$</TEX>), each of which was fed to apparent satiation for six weeks. In Exp-II, fish (<TEX>$44.3{\pm}0.4g$</TEX>) were reared at four stocking densities (1.5, 3.0, 4.5 and 6.0 <TEX>$kg/m^3$</TEX>) and fed a commercial diet to apparent satiation for four weeks. In Exp-III, fish (<TEX>$14.8{\pm}0.1g$</TEX>) were fed a commercial diet once, twice, thrice, <TEX>$4{\times}$</TEX> or <TEX>$5{\times}$</TEX> a day at a feeding ratio of 3.25% of body mass. Another group of fish was fed the same commercial diet <TEX>$5{\times}$</TEX> a day to apparent satiation; this treatment was designated FS (five times satiation/day). In Exp-IV, fish (<TEX>$31.3{\pm}0.1g$</TEX>) were fed a commercial diet once, twice, thrice or <TEX>$4{\times}$</TEX> a day to apparent satiation. Another group of fish was fed to apparent satiation once every 48 hours. In Exp-I, fish fed the large particle (4.0-5.3 mm) diet had a significantly higher feed conversion ratio and lower protein efficiency ratio than fish fed the small particle diet. In Exp-II, groups of fish reared at densities of 4.5 and 6.0 <TEX>$kg/m^3$</TEX> had significantly higher feed intake and growth performance than fish reared at 1.5 and 3.0 <TEX>$kg/m^3$</TEX>. In Exp-III, fish fed to apparent satiation had significantly higher growth performances than fish fed once or <TEX>$4{\times}$</TEX> a day. A significantly higher feed conversion ratio and a lower protein efficiency ratio were obtained in the FS group. In Exp-IV, growth performance and feed utilization efficiency were not significantly affected by experimental variation in feeding frequency. Fish fed to apparent satiation once every 48 hours had better feed utilization than those in other treatments and growth performances of those were comparable. Therefore, the optimum feed particle size, stocking density and feeding frequency for Korean rockfish under conditions we used were 2.0-3.2 mm, 4.5-6.0 <TEX>$kg/m^3$</TEX>, and once a day or once every 48 hour, respectively.

Effect of C/N ratio levels and stocking density of Labeo victorianus on pond environmental quality using maize flour as a carbon source

The main obstacle in developing intensive fish culture is waste management which is detrimental to the environment. To mitigate environmental impacts associated with effluent discharge, measures should be put in place to avoid deterioration of the pond environment. The addition of carbon materials into culture facilities while manipulating the levels of carbon and nitrogen ratios is one of the best strategies of controlling ammonia and nitrite in ponds. This study was carried out in 18 hapas suspended in six, 150m2 earthen ponds to investigate the effects of C/N ratios (10 and 20) and stocking density (10, 15 and 25 fish m−2) on water quality, sediment quality and growth of Labeo victorianus. All treatments were carried out in triplicate during a time period of 72days. A locally formulated and prepared feed containing 30% crude protein with a C/N ratio of 10 was applied. Maize flour was used as the carbohydrate source for manipulating C/N ratio and applied to the water column separately from the feed. Increasing C/N ratio from 10 to 20 reduced (P<0.001) the total ammonia nitrogen (TAN), nitrite–nitrogen (NO2–N) and nitrate–nitrogen (NO3–N) in the water column and total nitrogen in the sediment (P<0.001). It also raised sediment pH, organic matter and total phosphorus (P<0.001). The lowest protein efficiency ratio (PER), specific growth rate (SGR) and the highest food conversion ratio for the feed were recorded with a C/N ratio of 10 (P<0.05). Based on highest growth, survival, production and net benefits, C/N ratio of 20 and a stocking density of 25 fish m−2 are optimal. Therefore, carbohydrate addition in L. victorianus culture is a promising option for sustainable aquaculture.

Effect of four different commercial diets on growth perfomance of the cichlid fish, Oreochromis niloticus fingerlings

The present study deals with the effect of four commercially prepared diets on the length-weight relationship, condition factors, growth performance and feed utilization of the cichlid fish, Oreochromis niloticus fingerling reared in glass aquaria. The major components of diets included proteins, fats and carbohydrates of each feed type. The diets were analyzed for verification of values written on its commercial label. Data showed that, the standard length of the fish fed on the different diets did not vary significantly where it ranges between 6.28 ± 0.9 cm in diet II to 6.66 ± 0.8 cm in diet I. The same pattern of change was also noticed in comparing the weight of fishes fed on the four diets. Data indicated that, fish feeding on diet IV demonstrate the lowest weight being on the average of 8.86 ± 1.97 gm, while, fish feeding on diet I showed the highest weight being averaged 10.37 ± 3.2 gm. The growth of fish is nearly isometric in the first three diets and negative allometric in the fourth one. The values of condition factors are slightly differences among different diets. The highest value (3.46) of coefficient of condition (k) was recorded in the fish fed on diet II and the lowest value (3.09) in the fish fed on diet III. The highest average value (1.07) of the relative condition factor (kn) and the lowest (0.90) were recorded in the fish fed on diet III. The lowest value of total weight gain, average daily gain and specific growth rate were detected in the fish fed on diet IV. The value of feed intake of diet I is better than the values obtained from the other feed diets. The best feed conversion ratio (1.87) was recorded in the fish fed on diet II. The lower protein efficiency ratio (0.25) was recorded with diet IV and the higher protein efficiency ratio (0.53) was recorded with diet II.

EVALUACIÓN BIOLÓGICA EN RATAS DE LABORATORIO (Rattus norvegicus) DE FUENTES PROTEICAS USADAS EN ALIMENTOS COMERCIALES PARA PERROS

The aim of this study was to biologically assess three protein sources used in commercial dog food: soy meal (TS), meat meal (HC), and chicken meal (HP) using four biological tests: Protein Efficiency Ratio (PER), True Digestibility (DV), Net Protein Utilization (NPU) and Biological Value (VB). 40 albino laboratory rats of 23 days of age were used. Five groups were formed according to the protein source: groups TS, HC, HP, control group (sodium caseinate) and a non protein-group. The results were: PER: TS = 1.86, HC = 1.39, HP = 1.69, control = 2.11; DV: TS = 98.76, HC = 96.95, HP = 98.13, control = 99.19; NPU: TS = 58.19, HC = 35.52, HP = 60.19, control = 96.46; VB: TS = 0.59, HC = 0.37, HP = 0.61, control = 0.97. PER results in the HC group were significantly lower than other groups (p&lt;0.05). There was not statistical differences on PER between groups HP and TS. All protein sources had a high true digestibility. The HC was the protein source of less quality because the lowest PER, NPU and VB values. It is concluded that to asses the quality of protein nutrients is not enough to establish the protein content and digestibility, but to conduct biological tests.