Semi-purified Experimental Diets Research Articles

Novel sfericase protease improves amino acid digestibility of soybean meal and rapeseed meal in broiler chickens

ABSTRACT 1. Two experiments were conducted to explore the effects of an exogenous sfericase protease on the apparent ileal nutrient digestibility of soybean meal (SBM) and rapeseed meal (RSM) in broiler chickens. 2. In each experiment, a total of 256 sixteen-day-old male Cobb 500 broilers were fed one of four semi-purified experimental diets, comprising two different batches (A and B) of samples for either SBM (Exp. 1) or RSM (Exp. 2) without or with an exogenous sfericase (0 or 30,000 NFP/kg). Each experimental diet was fed to eight replicate pens of broiler chickens from 16 to 21 d of age (eight birds per cage), and ileal digesta were collected for measuring the digestibility coefficients. 3. In Exp. 1, the amino acid digestibility was greater (P < 0.05) in SBM B compared with SBM A for Arg and Val, and a similar trend (P < 0.1) was observed for Tyr, Leu and Thr. Exogenous sfericase increased (P < 0.10) digestibility of most of amino acids except Gly, His and Trp. There was an interaction between SBM source and sfericase, whereby digestibility of P, N and Asp was increased by sfericase for SBM B but not for SBM A. In Exp. 2, there was no interaction (P > 0.05) between RSM source and sfericase for ileal nutrient digestibility. Digestibility was greater in RSM A compared to RSM B for all non-essential AA and most essential AA (except for Trp), while the reverse was noted for Ca and P (P < 0.05). Exogenous sfericase increased (P < 0.1) digestibility for all amino acids except Cys and Met. 4. In conclusion, the current studies showed that both SBM and RSM batches influenced amino acid digestibility. Sfericase protease supplementation increased amino acid digestibility for both SBM and RSM. The digestibility effects were greater in the SBM batch with low digestibility for N and Asp which was in line with an increase in P digestibility.

Partial Substitution of Fishmeal with Plant Protein Source the Soybean Meal in the Diets of Arabian Yellowfin Seabream Acanthopagrus arabicus Juveniles

The present study was designed to assess the alternate environmental friendly source of protein; here we report the suitability of soybean meal as a plant protein source for partial replacement of fishmeal in the diet of Arabian yellowfin seabream Acanthopagrus arabicus; reared in floating net cages. A total of 56 days feeding trial was conducted to evaluate the growth performance, feed utilization, survival, and carcass composition of the juveniles. Triplicate groups (30 fish/cage) of A. arabicus (initial weight 22.61 ± 0.11 g) were stocked in floating net cages (1.5 × 1.5 × 1.5 m). Five semi-purified experimental diets, each containing 42% dietary protein, were prepared where fishmeal was replaced with soybean meal: 0% (control), 20% (SBM20), 40% (SBM40), 60% (SBM60) and 80% (SBM80). Fish were fed twice daily at 7% body weight. The formulated diet was well accepted by the fish, where, 100% of survival was recorded at the end of the experiment. No significant differences (P > 0.05) were observed in final weight gain (WG) and specific growth rate (SGR) of juvenile Arabian yellowfin seabream fed on SBM20 and SBM40 diets compared to the control diet. However, a decline in growth performance was recorded in fish received SBM60 and SBM80 diets. Poor feed conversion ratio (FCR) was observed for fish fed with increasing dietary soybean meal above SBM40. No significant differences (P > 0.05) were found in the final whole-body carcass composition of proteins, moisture, and ash. However, the lipid content in the fish body increased significantly (P < 0.05) with an increasing soybean meal and fish oil in the diets. Our results showed that 40% of SBM could substitute fishmeal without jeopardizing the health and growth of Arabian yellowfin seabream.

Effects of vitamin C deficiency or excess on growth performance, anti-oxidative response and fatty acid composition of juvenile abalone Haliotis discus hannai Ino

A 240-day feeding trial was conducted to investigate the effects of dietary vitamin C on growth performance, anti-oxidative response, and fatty acid composition of juvenile abalone Haliotis discus hannai Ino (initial body weight: 0.93±0.00 g). Three semi-purified experimental diets were formulated containing 0.00, 94.52, and 9 649.58 mg/kg of vitamin C supplied as L-ascorbyl-2-monophosphate. The results show that there was no significant difference in weight gain ratio, daily increment in shell length, and survival rate among the three treatments. Adding dietary vitamin C (9 649.58 mg/kg) significantly increased the activities of superoxide dismutase (SOD), glutathine peroxidase (GPX), glitathione-S-transferase (GST), glutathione reductase (GR), alkaline phosphatase (AKP), and lysozyme in viscera (P<0.05). In muscle, activities of phenoloxidase, catalase, SOD, GST, GR, and AKP were increased in the treatment with 9 649.58 mg/kg of dietary vitamin C (P<0.05). The highest concentrations of ascorbic acid in viscera and muscle were found in the group with 9 649.58 mg/kg of dietary vitamin C (P<0.05). The contents of crude protein and crude lipid in the soft body were significantly increased in the 9 649.58 mg/kg group (P<0.05). Dietary vitamin C supplementation significantly decreased the contents of saturated fatty acids (14:0, 16:0, and 18:0), and increased the composition of 18:2n-6 and 22:6n-3 in the soft body of abalone (P<0.05). Therefore, although there were no significant effects on the growth performance, dietary vitamin C supplementation improved the anti-oxidation and immune responses, increased specific unsaturated fatty acid (i.e., 16:1, 18:1n-7, 18:1n-9, 18:2n-6 and 22:6n-3), and decreased specific saturated fatty acid (i.e., 14:0, 16:0 and 18:0) contents in the soft body of abalone.

Optimum level of dietary lipids for growth, chemical composition and apparent digestibility of lipids for Atractosteus tropicus

Lipids requirement of tropical gar Atractosteus tropicus prejuveniles and juveniles was evaluated on growth, survival, chemical composition and apparent digestibility coefficient (ADC). Four semi-purified experimental diets (5, 10, 15 and 20% of lipids) were obtained with a mix of menhaden oil and soybean lecithin (2:1 ratio). Two trials were carried out, first with 600 prejuveniles of 0.5 g (35 days post-hatching, dph) for 56 days, and the second with 160 juveniles of 15 g (two-months-old) for 42 days. In the first trial, 15 (40.8 g) and 20% (40.2 g) lipid diets showed the best weight. Significant differences were obtained in condition factor (CF), daily lipid intake (DLI), hepatosomatic index (HSI), crude protein, ashes, nitrogen-free extract, moisture and ether extract between treatments. In the second trial, fish fed with the 10% lipid diet obtained the highest weight (89.1 g) compared with the other treatments. Significant differences were recorded for weight gain (WG), feed conversion ratio (FCR), specific growth rate (SGR), condition factor (CF), and lipid efficiency rate (LER). Also, significant differences were obtained in crude protein, ether extract, NFE, gross energy, apparent lipid ADC, protein ADC and dry matter ADC. The polynomial models applied to both trials indicated an optimum lipid requirement of 17% for 0.5 g juveniles and of 9% for 15.2 g juveniles.

Amino acid digestibility of corn distillers’ dried grains with solubles with the addition of casein in pigs1

This experiment was conducted to determine the ileal digestibility of CP and AA in casein by regression analysis and to investigate the effects of casein in experimental diets on the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA in corn distillers' dried grains with solubles (DDGS) fed to pigs. Twenty barrows (initial BW = 50.5 ± 4.46 kg) surgically fitted with T-cannulas at the distal ileum were used. Eighteen pigs were assigned to a triplicate 6 × 3 incomplete Latin Square design with 6 diets and 3 periods. Two pigs were used as replacements. Three diets were prepared to contain 60, 100, or 140 g/kg casein to determine the ileal digestibility of CP and AA in casein by regression analysis, and 2 diets were prepared to contain either 480 g/kg DDGS or 308 g/kg DDGS and 60 g/kg casein. Casein and DDGS were the sources of nitrogen (N) in experimental diets. A N-free diet was prepared based on cornstarch and dextrose. Experimental periods consisted of 5 d of adaptation and 2 d of ileal digesta collection periods. The AID of CP and AA in casein linearly increased (P < 0.01) with increasing concentration of casein in the diets. The SID of indispensable AA in casein ranged from 94.7% (SEM = 1.16) for Ile in pigs fed the diet containing 60 g/kg casein to 103.3% (SEM = 2.21) for Arg in pigs fed the diet containing 100 g/kg casein. Except for Arg, pigs fed the diet containing DDGS and casein had greater (P < 0.001) SID of CP and indispensable AA than those fed the diet containing DDGS without casein. The ileal digestibility of indispensable AA in casein determined by regression analysis ranged from 96.8% (SE = 3.14) for Thr to 103.1% (SE = 4.40) for Arg. The AID and SID of CP and AA for DDGS in the diet containing casein were calculated by difference method using the ileal digestibility of CP and AA in casein determined by regression analysis. The AID of Lys for DDGS in the diet containing casein was greater (P = 0.035) than those without casein; however, the AID of CP and the other indispensable AA, except for Arg, Phe, and Trp, for DDGS in the diet containing casein was less (P < 0.05) than those without casein. The SID of Lys and Phe for DDGS in the diet containing casein was greater (P < 0.05) than those without casein. In conclusion, improved AA composition in semi-purified experimental diets may affect the SID of AA in low-quality protein ingredients.

Protein sparing capability of carbohydrate in fringed-lipped carp Labeo fimbriatus (Bloch, 1795)

The study was undertaken to examine the capability of carbohydrate to spare protein in the diet of fringed lipped carp, Labeo fimbriatus (2.93 g±0.15). Three semi-purified experimental diets of iso-caloric nature were formulated having three graded levels of protein (27, 23 and 19% CP) and three levels of carbohydrate (26, 31.5 and 37% CHO). Accordingly, the treatments were designated as T1 (27% CP and 26% CHO), T2 (23% CP and 31.5% CHO) and T3 (19% CP and 37% CHO), where the experimental diet T1 served as the reference diet. The fish were reared in 200 l fibre reinforced plastic (FRP) tanks under continuous aeration with one third water exchanged daily. After 90 days of feeding trial, it was noticed that the percentage weight gain and specific growth rate (SGR) of 27% protein fed group (209.5±0.74% and 1.26±0.15%) and 23% protein fed group (204.8±0.52% and 1.24±0.13%) were not significantly different (p&gt;0.05). Similarly, the results of feed performance like feed conversion ratio (FCR) among 27% protein fed group (2.24±0.11) and 23% protein fed group (2.29±0.14) did not vary significantly (p&gt;0.05). On the other hand, the protein efficiency ratio (PER) and protein productive value (PPV) of 23% protein fed group (1.87±0.11 and 28.34±0.36) did not vary significantly (p&gt;0.05) with the 19% protein fed group (1.93±0.12 and 27.65±0.32). The carcass protein (CP) and lipid (as ether extract,EE) content of 27% protein fed group and 23% protein fed group were not significantly different (p&gt;0.05). Results of this study indicate that the CP level in the diet of fringed-lipped carp L. fimbriatus can be reduced from 27 to 23% by proportionately increasing carbohydrate level from 26 to 31.5% without compromising growth and also without any adverse physiological effect.

True phosphorus digestibility of camelina meal in broiler chickens

This study was conducted to determine the true digestibility of phosphorus (P) in two different cold-pressed camelina meals using regression method. Six semi-purified experimental diets containing 120, 240, or 360 g of camelina meal (CM) per kilogram from camelina meal 1 (CM1) and camelina meal 2 (CM2) were formulated. A total of 384 male Ross 708 broilers were allocated to six dietary treatments with eight cages per treatment from day 18 to day 23 post hatching in a randomized complete block design. The result showed that body weight gain, gain:feed ratio, ileal dry matter (DM) digestibility, DM and nitrogen (N) retention decreased (linear, P < 0.001) with increasing levels of CM1 and CM2. Apparent ileal digestibility of P and Ca decreased (P < 0.01) with increasing dietary levels of CM. From the regressions of ileal and excreta P output against intake of P from CM1 or CM2, true ileal P digestibility and true P retention were determined to be 35% and 15%, and 24% and 21% for CM1, and CM2, respectively. R...

Synergistic effects of dietary nano selenium and vitamin C on growth, feeding, and physiological parameters of mahseer fish (Tor putitora)

The current study was conducted to determine the synergistic effects of dietary nano selenium (Nano Se) and vitamin C on growth, feeding, and physiological parameters of juvenile mahseer, Tor putitora. L-ascorbyl-2-polyphosphate (APP) was used as a source of vitamin C. Four semi-purified experimental diets were prepared. A basal diet kept without the supplementation of any micronutrient and the other three diets were formulated such that three different levels of APP (100, 200, and 300mgkg−1) were used in combination with a pre-determined dose of Nano Se (0.68mgkg−1). The results showed that both the micronutrients positively synergized the effects of each other. APP at the rate of 300mgkg−1 showed strong interaction with Nano Se. The APP300+Nano Se0.68 mgkg−1 diet supplemented diet significantly decreased (P<0.05) the feed conversion ratio (FCR) while significantly increased (P<0.05) the weight gain percentage (WG%), feed conversion efficiency (FCE%), specific growth rate (SGR), and serum growth hormone (GH) concentration. Similarly, the physiological parameters such as red blood cells count (RBCs), hemoglobin level (Hb), hematocrit value (Hct), and serum lysozyme activity were also significantly increased in group of fish fed diet supplemented with APP100 mgkg−1 in combination with Nano Se0.68 mgkg−1 as compared to the control group. The present results clearly indicated the beneficent synergistic effects of Nano Se and APP in mahseer fish. Moreover, the current finding also supported our hypothesis that Nano Se and APP potentiate positively the effect of each other when both the micronutrients are supplemented together in the same fish feed.

The implications of substituting dietary fish oil with vegetable oils on the growth performance, fillet fatty acid profile and modulation of the fatty acid elongase, desaturase and oxidation activities of red hybrid tilapia, Oreochromis sp.

A 75-day feeding trial was carried out to examine the effects of fish oil (FO) replacement with various alternative vegetable oil (VO) on the growth performance and feed utilization efficiency of red hybrid tilapia (Oreochromis sp.). The VO evaluated included canola oil (high in monoenes), perilla oil (high in n−3 polyunsaturated fatty acids, PUFA), sunflower oil (high in n−6 PUFA) and refined, bleached, deodorized palm olein (high in saturates) added as the sole lipid source in semi-purified experimental diets. The ability of hybrid tilapia to biosynthesize long chain-polyunsaturated fatty acids (LC-PUFA) from dietary 18:2n−6 and 18:3n−3 was also determined. With the exception of sunflower oil, results showed that total FO replacement by various VO did not compromise (P>0.05) tilapia growth performance. However, dietary VO significantly (P<0.05) influenced the fatty acid composition of tilapia fillet and whole-body lipids through changes in the overall fatty acid metabolism. The total Δ5 and Δ6 fatty acid desaturase activities were exclusively triggered in tilapia fed VO-based diets. Tilapia fed the VO diets, which contained no PUFA longer than C18, recorded significant amounts of both n−6 and n−3 LC-PUFA in their tissue lipids. Dietary canola oil (CO) increased Δ-6 desaturation of 18:3n−3 to the greatest extent despite the dietary 18:3n−3 content being comparatively lower than dietary perilla oil (PeO). Beta-oxidation of 18:3n−3 was observed to be highest in fish fed the PeO diet, indicating that the 18:3n−3 content in the PeO diet exceeded the optimum substrate level for Δ-6 desaturase. Omega-3 LC-PUFA biosynthetic activities were highest in fish fed the CO diet and resulted in a comparatively higher eicosapentaenoic acid (EPA)+docosahexaenoic acid (DHA) content than in fish fed other VO diets. However, endogenous LC-PUFA synthesis induced by the VO diets was insufficient to rival the n−3 LC-PUFA content of fish fed the FO diet. It was also observed that β-oxidation of 18:3n−3 and 18:2n−6 was regulated by tissue n−3/n−6 PUFA ratio and proportional to their dietary level. This study provided the first comprehensive evidence of the significant impact of dietary oils with different fatty acid class profile on the in vivo fatty acid metabolism of tilapia. Statement of relevanceMarine fish oil (FO) was traditionally used as the major lipid source in commercial tilapia feeds to provide energy and essential fatty acids as well as to impart palability to the feed. With the rising costs of FO and limited global supplies, the use of alternative lipid resources in aquafeeds, including tilapia feeds, has become more critical to enable the continued sustainability and scalability of the global aquaculture industry. Terrestrial vegetable oil (VO) are viable alternatives since their production is more sustainable and cost-effective. However, unlike FO, which is rich in n−3 long chain-polyunsaturated fatty acids (LC-PUFA), VO are deficient in these essential fatty acids and but high in other fatty acid classes. The present study evaluated perilla oil (high levels of n−3 polyunsaturated fatty acids), sunflower oil (rich in n−6 PUFA), canola oil (high amounts of monounsaturated fatty acids) and palm oil (rich in saturated fatty acids) together with fish oil. By understanding how dietary lipid source with different major fatty acid classes modulates in vivo fatty acid metabolism, we can better formulate fish feeds that can optimize not only growth performance but also maintaining the health benefits of eating seafood for the human consumer in regards to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels in farmed fish fillets. As far as we know, there is currently no information comparing the fatty acid metabolism of red hybrid tilapia fed diets with lipids containing different major fatty acid classes.

Energy and nutrient utilisation of broilers fed soybean meal from two different Brazilian production areas with an exogenous protease

A study was conducted to evaluate the effects of an exogenous protease added to diets having soybean meal (SBM) from two geographic areas in Brazil (South or North). Evaluation was conducted on energy utilisation and nutrient digestibility using 224 slow feathering Cobb×Cobb 500 male broilers. Birds were fed a common starter diet to d 15. Semi-purified experimental diets containing 555g/kg SBM and 408g/kg maize starch plus minerals and vitamins were provided afterwards until 24 d. Diets had 0.1g/kg phytase and 10g/kg Celite (indigestible marker). Birds were randomly distributed in a 2×2 factorial arrangement of the two SBM with or without protease supplementations (0 or 15,000 protease units/kg) from 17 to 24 d. Excreta were collected from 21 to 23 d and ileal content was collected from all birds. Samples of feed, excreta, and ileal content were analysed for determination of total tract retention and ileal apparent digestibility. No interactions between SBM and protease were observed. Broilers fed semi-purified diets formulated with South SBM had lower (P<0.05) ileal digestibility of crude protein and also from most amino acids (AA) when compared with birds fed North SBM. Ileal digestible energy was increased (P<0.01) by 0.51MJ/kg when birds were fed the diet supplemented with protease. Indispensable and dispensable AA digestibility also increased (P<0.05) with protease supplementation. Ileal digestibility coefficients of Met, Lys, Thr and Val were increased (P<0.05) by 3.1%, 3.1%, 4.8%, and 3.3%, respectively when birds were fed the diet supplemented with protease. Results from this experiment show that utilisation of energy and AA from SBM depends on its origin, but protease supplementation improved their utilisation regardless of the SBM source.

Effects of varying levels of dietary vitamin E (α-tocopherol) on growth performance, proximate and fatty acid composition of juvenile silver pomfret (Pampus argenteus Euphrasen, 1788)

Summary This study investigated the effects of elevated dietary levels of vitamin E (α-tocopherol) on growth performance, proximate composition and fatty acid profiles of juvenile silver pomfret, Pampus argenteus. Three semi-purified experimental diets were formulated to contain 49% protein and 16% lipid. High docosahexaenoic acid (DHA) tuna oil was added to the diets to supplement DHA. A graded level of vitamin E (0-, 50-, and 100 mg kg−1) was added to experimental diets 1 to 3, respectively. Analyzed vit. E levels were 155.2, 195.3 and 236.4 mg kg−1 in diets 1, 2 and 3, respectively. The experiment was conducted for 12 weeks with juvenile silver pomfret (29.6 ± 7.6 g) using a flow-through system consisting of nine 1-m3 tanks. Each treatment had three replicates and fish were stocked at the rate of 20 m−3. Growth performance and feed utilization parameters of fish fed diets 2 and 3 were significantly (P 0.05). Although whole body protein levels were not influenced by the dietary vit. E levels, whole body lipid in fish fed diet 2 was significantly higher than in fish fed the other diets. The whole body vit. E levels in fish fed diet 2 (22.6 mg kg−1) and diet 3 (24.1 mg kg−1) were significantly (P < 0.05) higher than in those fed diet 1 (18.2 mg kg−1). Whole body total saturated fatty acids were significantly lower, and DHA levels higher in fish fed diets 2 and 3 than those fed diet 1. The results of the present study suggest that increasing dietary supplementation of vit. E in high lipid diets enhances the growth performance of fish and that a dietary level of 196 mg kg−1 vit. E is suitable for the growth of silver pomfret.

Evaluation of optimum dietary vitamin E requirements using DL-α-tocopheryl acetate in the juvenile eel, Anguilla japonica

Summary The study aimed at evaluating the optimum dietary vitamin E requirements using DL-α-tocopheryl acetate in the juvenile eel, Anguilla japonica, as assessed by fish growth performance and fish body composition. Five semi-purified experimental diets were formulated to contain 0 (TA1), 15 (TA17), 30 (TA32), 60 (TA62) and 120 (TA119 mg TA kg−1 diet on a dry matter (DM) basis in the form of DL-α-tocopheryl acetate (TA). After a 4-week conditioning period, fish (15 ± 0.3 g) were randomly distributed into aquaria in groups of 20 at 25 ± 1.0°C (mean ± SD). One of the five diets was fed on a DM basis to fish in three randomly selected aquaria twice daily to satiation (approximately 3% of wet body weight per day at the beginning and 2% of wet body weight per day at the end of the feeding trial) for 12 weeks. At the end of the 12-week feeding trial, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) were determined; these were significantly lower in control fish than in fish fed supplemented diets (P 0.05). There were also no significant differences in SGR among fish fed TA32, TA62 or TA119 (P > 0.05). A broken-line regression analysis on the basis of WG, SGR, FE and PER showed that dietary vitamin E requirements of juvenile eels were 21.2, 21.6, 21.2 and 21.5 (mg kg−1 diet), respectively. These results indicate that the dietary vitamin E requirement could be <21.2 mg kg−1 but <21.6 mg kg−1 diet in juvenile eel, A. japonica, when DL-α-tocopheryl acetate is used as the dietary vitamin E source.

Re-evaluation of the Optimum Dietary Vitamin C Requirement in Juvenile Eel, Anguilla japonica by Using L-ascorbyl-2-monophosphate.

This study was conducted to re-evaluate the dietary vitamin C requirement in juvenile eel, Anguilla japonica by using L-ascorbyl-2-monophosphate (AMP) as the vitamin C source. Five semi-purified experimental diets were formulated to contain 0 (AMP0), 30 (AMP24), 60 (AMP52), 120 (AMP108) and 1,200 (AMP1137) mg AMP kg-1 diet on a dry matter basis. Casein and defatted fish meal were used as the main protein sources in the semi-purified experimental diets. After a 4-week conditioning period, fish initially averaging 15±0.3 g (mean±SD) were randomly distributed to each aquarium as triplicate groups of 20 fish each. One of five experimental diets was fed on a DM basis to fish in three randomly selected aquaria, at a rate of 3% of total body weight, twice a day. At the end of the feeding trial, weight gain (WG) and specific growth rate (SGR) for fish fed AMP52 and AMP108 were significantly higher than those recorded for fish fed the control diet (p<0.05). Similarly, feed efficiency (FE) and protein efficiency ratio (PER) for fish fed AMP52 were significantly higher than those for fish fed the control diet (p<0.05). Broken-line regression analysis on the basis of WG, SGR, FE and PER showed dietary vitamin C requirements of juvenile eel to be 41.1, 41.2, 43.9 and 43.1 (mg kg−1 diet), respectively. These results indicated that the dietary vitamin C requirement could range from 41.1 to 43.9 mg kg−1 diet in juvenile eel when L-ascorbyl-2-monophosphate was used as the dietary source of vitamin C.

Effects of Dietary Arachidonic Acid (20:4n-6) Levels on Growth Performance and Fatty Acid Composition of Juvenile Eel, Anguilla japonica

This study was conducted to evaluate the effects of dietary arachidonic acid (AA, 20:4n-6) levels on growth performance and body composition in juvenile eel, Anguilla japonica. Six semi-purified experimental diets were formulated to be isonitrogenous and iso-caloric containing 55.0% crude protein and 15% crude lipid (18.3 kJ of available energy g -1 ). Six different levels of AA were added to the basal diet, with 0, 0.2, 0.4, 0.6, 0.8 or 1.2% on a dry matter (DM) basis, respectively (AA 0.07 , AA 0.22 , AA 0.43 , AA 0.57 , AA 0.78 or AA 1.23 ). After a conditioning period, fish initially averaging 27±0.5 g (mean±SD) were randomly distributed into each aquarium as triplicate groups of 20 fish each. One of six experimental diets was fed on a DM basis to fish in three randomly selected aquaria at a rate of 2-3% of total body weight twice a day. At the end of the 12-week feeding trial, weight gain (WG) and feed efficiency (FE) of fish fed AA 0.78 and AA 1.23 diets were significantly higher than of fish fed AA 0.07 , AA 0.22 and AA 0.43 diets (p 0.05). Whole body AA deposition of fish fed the AA 1.23 diet was significantly higher than for the other diets (p<0.05). Broken-line model analysis on the basis of WG and SGR indicated that the dietary AA requirement could be greater than 0.69% but less than 0.71% of the diet in juvenile eel. The growth-promoting activity of AA observed in the present study provides strong support for the contention that dietary AA is essential for juvenile eel.

A dietary energy level of 14.6 MJ kg−1and protein-to-energy ratio of 20.2 g MJ−1results in best growth performance and nutrient accretion in silver barbPuntius gonionotusfingerlings

Five iso-nitrogenous (300 g protein kg−1 diet) and iso-lipidic (80 g kg−1 diet) semi-purified experimental diets with variable energy levels of 10.5 (D-1), 12.5 (D-2), 14.6 (D-3), 16.7 (D-4) and 18.8 (D-5) MJ kg−1 diets were fed to Puntius gonionotus fingerlings (average weight 1.79 ± 0.02 g) in triplicate groups (15 healthy fishes per replicate) for a period of 90 days to assess the optimum dietary energy level and protein-to-energy ratio (P/E). Fifteen flow-through cement tanks of 100 L capacity with a flow rate of 0.5 L min−1 were used for rearing the fish. Maximum specific growth rate, protein efficiency ratio, protein productive value, RNA : DNA ratio, whole body protein content, digestive enzyme activity and minimum feed conversion ratio was found in fish-fed diet D-3 with 14.6 MJ kg−1 energy level. There were no improvements in all these parameters with the further rise in dietary energy level. Hence, it may be concluded that the optimum dietary gross energy level for maximum growth and nutrient utilization of silver barb is 14.6 MJ kg−1 diet with a resultant P/E ratio of 20.2 g protein MJ−1 diet, when the dietary protein and lipid are maintained at optimum requirement levels of 300 and 80 g kg−1 diet, respectively, for this species.

Effects of raw corn starch levels on growth, feed utilization, plasma chemical indices and enzyme activities in juvenile yellowfin seabream Sparus latus Houttuyn

A 10-week growth trial was conducted to evaluate the effect of raw corn starch levels on the growth, feed utilization, plasma chemical indices and metabolic enzyme activities of juvenile yellowfin seabream Sparus latus. Four semi-purified experimental diets with different raw corn starch levels (5%, 10%, 20% and 26%) and a high-protein control diet were prepared before the experiment and hand-fed to triplicate groups of juvenile yellowfin seabream Sparus latus. Weight gain and specific growth rate for fish fed the diet containing 26% raw corn starch were significantly lower than those for fish fed 10% or 20% corn starch diets or the high-protein control diet. Fish fed 10% or 20% corn starch diets had a slightly better growth performance than those fed the 5% corn starch diet. Feed efficiency ratio and protein efficiency ratio (PER) for 20% raw corn starch fed fish were the highest among all groups, although no statistically significant differences were found among the experimental groups. The high-protein control group had a significantly lower PER value than other groups. Protein productive values for fish fed the 5% raw corn starch diet and the high-protein control diet were significantly lower than those of fish fed the 20% raw corn starch diet, but not significantly different from the values of any other group. The values of intraperitoneal fat ratio, viscerosomatic index and condition factor, as well as body and muscle compositions, were unaffected by corn starch levels. The hepatosomatic index and liver glycogen level for fish fed 5%, 10%, 20% raw corn starch and the high-protein control diets were equal but significantly lower compared with that of fish fed the 26% raw corn starch diet. Plasma values of the fish were not affected by various dietary treatments, except that a significantly higher plasma glucose concentration was measured in the high-protein control group compared with the values in the other groups. There were variations in the activities of hepatic hexokinase and pyruvate kinase of the yellowfin seabream after they had been fed different dietary raw corn starch levels for 10 weeks. The overall results showed that a 20% inclusion level of raw corn starch in the diet was better utilized by juvenile yellowfin seabream than 5%, 10% or 26% levels and had a protein-sparing effect.

Protein-sparing effect of carbohydrate in silver barb, Puntius gonionotus fry

A 30-day study was undertaken to examine the protein-sparing effect of carbohydrate in diets for silver barb, Puntius gonionotus fry. Six semi-purified experimental diets were formulated with two levels of protein (200 and 250 g kg⁻¹ diet) and three levels of carbohydrate (300, 340 and 380 g kg⁻¹ diet). In addition to the six experimental diets, a diet containing the protein and carbohydrate requirement levels of 300 and 260 g kg⁻¹ diet, respectively, as reported earlier for this species, was used as a reference diet. For each dietary treatment, 30 healthy fry of 20 days age (0.12 ± 0.01 g) were stocked in triplicate tanks using a flow-through system. The fish were fed ad libitum four times a day to a level close to apparent satiation. Batch weighing of fish was done after 15 days of stocking to measure growth and general health status of the fish. The fish fed 250 g protein and 340 g carbohydrate kg⁻¹ diet with a protein to energy ratio of 17.86 g protein MJ⁻¹ performed equally well in terms of growth and nutrient utilization as the reference diet group. The study indicates that dietary protein can be reduced from 300 to 250 g kg⁻¹ diet by increasing carbohydrate from 260 to 340 g kg⁻¹ diet without sacrificing the growth of silver barb fry.

Effects of dietary oil source on growth and fillet fatty acid composition of Murray cod, Maccullochella peelii peelii

The Murray cod, an Australian native freshwater fish, supports a relatively small but increasing aquaculture industry in Australia. Presently, there are no dedicated commercial diets available for Murray cod; instead, nutritionally sub-standard feeds formulated for other species are commonly used. The aim of the present investigation was to assess the suitability of two plant based lipid sources, canola oil (CO) and linseed oil (LO), as alternatives to fish oil for juvenile Murray cod. Five iso-nitrogenous, iso-calorific, iso-lipidic semi-purified experimental diets were formulated with 17% lipid originating from 100% cod liver oil (FO), 100% canola oil, 100% linseed oil and 1 : 1 blends of canola and cod liver oil (CFO) and 1 : 1 blends of linseed and cod liver oil (LFO). Each of the diets was fed to apparent satiation twice daily to triplicate groups of 50 Murray cod with initial mean weights of 6.45 ± 1.59 g for 84 days at 22 °C. Final mean weight, specific growth rate and daily feed consumption were significantly higher for the FO and LFO treatments compared to the LO treatment. Feed conversion and protein efficiency ratios were not significantly different amongst treatments. Experimental diets containing vegetable oil and vegetable oil blend(s) had significantly higher concentrations of n-6 fatty acids, predominantly in the form of linoleic acid (LA), while n-3 fatty acids were present in significantly higher concentrations in LO and LFO treatments. The fatty acid composition of Murray cod fillet was reflective of the dietary lipid source. Fillet of fish fed the FO was highest in EPA (20:5n-3), ArA (20:4n-6) and DHA (22:6n-3). Fish fed the CO diet had high concentrations of oleic acid (OlA) (192.2 ± 10.5 mg g lipid − 1 ), while the fillet of Murray cod fed the LO diet was high in α-linolenic acid (LnA) (107.1 ± 6.7 mg g lipid − 1 ). The present study suggests that fish oil can be replaced by up to 100% with canola oil and by up to 50% with linseed oil in Murray cod diets with no significant effect on growth.

Availability of environmental and dietary calcium in tiger puffer

Tiger puffer, Takifugu rubripes, juveniles were fed with four semi-purified experimental diets containing 0.2% Ca from Ca-lactate (diet 1), no supplemental Ca (diet 2) and 0.2% and 2.5% Ca from tricalcium phosphate, TCP (diets 3 and 4), respectively. After a 10 week rearing period, growth and feed utilization were significantly lower in the fish group fed on diet 2 than in the fish group fed on diet 1. Fish groups fed on diets 3 and 4 also showed poor growth performances compared with group 1. It appears that Ca intake from seawater is not sufficient for the normal growth of tiger puffer. Furthermore, Ca in dietary TCP appeared to be unavailable to this species. Dietary TCP strongly inhibited the bone mineralization of Zn and Mn. The findings indicate that easily digestible Ca supplementation is indispensable in a diet of tiger puffer for normal growth, feed utilization and bone mineralization. © Rapid Science Ltd. 1998

Essential fatty acid requirement of the Chinese prawn, Penaeus chinensis

The aim of this study was to determine the essential fatty acid (EFA) requirement of one of the most important commercially cultured crustacean species in the world, Penaeus chinensis. Groups of 16 individually housed juvenile Chinese prawn were fed for 60 days with 12 semi-purified experimental diets. These diets were based on the crab-protein-concentrate Standard Reference Diet and contained either 5% of a mixture of tripalmitin (16:0) and triolein (18:1 n−9) (EFA deficient control diet), or 4% of this mixture and a 1% supplement of various purified polyunsaturated fatty acids (PUFA) or highly unsaturated fatty acids (HUFA). Prawns fed the EFA-deficient control diet suffered 100% mortality. The prawns fed a diet containing 1% trilinolenin (18:3 n−3) had higher growth and longer survival than that of animals fed the diet containing 1% trilinolein (18:2 n−6). Feeding a diet containing a mixture 0.5% of each of these lipids resulted in a greater growth rate and a 0.25:0.75 mixture of trilinolein and trilinolenin produced a greater survival than any other mixture or either purified fatty acid supplement alone. When the 18-carbon polyunsaturated fatty acid supplement was replaced with 1% of the triglyceride of arachidonic acid in the diet fed to prawns, however, the growth was about equal to that of prawns receiving 1% 18:3 n−3 and survival was significantly higher than that of prawns fed any combination of 18:2 n−6 or 18:3 n−3 tested, while being less than that of prawns fed a diet containing 1% of the triglyceride of docosahexaenoic acid (DHA, 22:6 n−3). The prawns fed the EFA-deficient control diet or any of the diets with 18:2 n−6 or 18:3 n−3 supplemented individually had extremely low body lipid levels. Mixtures of these two fatty acids or any combination of the n−6 or n−3 HUFA resulted in more normal body lipid levels, suggesting that both n−3 and n−6 type fatty acids might be required by the Chinese prawn. The fatty acid composition of the total body lipid reflected that of the experimental diets. Though 18:2 n−6 and 18:3 n−3 were not apparently desaturated and elongated to the physiologically important EFA members of the respective n−6 and n−3 series of fatty acids (20:4 n−6, 20:5 n−3 and 22:6 n−3), there was evidence for elongation of these acids to 20:2 n−6 and 20:3 n−3. The results indicate that the essential fatty acid values of the fatty acids in the diet of the Chinese prawn increased in the following order 18:2 n−6 < 18:3 n−3 < 20:4 n−6 < 22:6 n−3.