Dietary vitamin C requirement of genetically improved farmed Tilapia,Oreochromis Niloticus

A 12‐week growth experiment was conducted to quantify the appropriate dietary vitamin C requirement for GIFT tilapia Oreochromis niloticus. Triplicate groups of 25 experimental tilapia [initial body weight: (70.0 ± 1.6) g] were cultured in 5.6‐m³ aquaria (r = 1.5 m,h = 0.8 m) and fed with semi‐purified diets containing six levels [6.1 (un‐supplemented diet], 23.8, 41.9, 85.1, 167.4 and 339.0 mg kg^?1 diet respectively) of vitamin C (supplied as L‐ascorbyl‐2‐polyphosphate). The results showed that, increasing dietary vitamin C level up to 41.9 mg kg^?1 diet increased weight gain rate of tilapia, beyond which it remained nearly unchanged. Vitamin C contents in liver and muscle presented first increased linearly then tended to reach saturation at high vitamin C (167.4 and 339.0 mg kg^?1) treatments. Muscle collagen content significantly increased with increasing dietary vitamin C levels. Whole‐body lipid content significantly increased, whereas ash content significantly declined, but moisture and crude protein content showed no significant difference with the increasing of dietary vitamin C. The blood chemistry analysis showed that dietary vitamin C had significant effects on enzyme activities of serum alkaline phosphatase, aspartate aminotransferase and alanine aminotransferase. Significant effects were also observed on albumin and total protein content of serum, but haemoglobin content showed no significant differences among all the treatments. The vitamin C requirement for GIFT tilapia was estimated to be 45.0 mg kg^?1 diet based on maximum growth, 114.9 and 118.6 mg kg^?1 diet based on maximum liver and muscle vitamin C concentration respectively.     

Effects of dietary cecropin on growth,non‐specific immunity and disease resistance of tilapia (Oreochromis niloticus × O. aureus)

An 8‐week feeding trial was conducted to evaluate the effect of dietary cecropin on growth performance, non‐specific immunity and disease resistance of hybrid tilapia (Oreochromis niloticus × O. aureus). A basal diet was supplemented with 0 (control), 75, 150 and 225 mg kg^?1 cecropin to formulate four experimental diets. The results showed that final body weight and specific growth rate obtained with diet 150 mg kg^?1 cecropin were significantly higher (P < 0.05) than that obtained with diets 0 and 75 mg kg^?1, whereas there was no difference between 150 and 225 mg kg^?1. Feed conversion efficiency was improved by increasing the dietary cecropin content (P < 0.05). However, feeding intake was reduced as dietary cecropin increased. Serum lysozyme, alkaline phosphatase, catalase and superoxide dismutase activity were significantly increased with the increased levels of dietary cecropin (P < 0.05), and reached a maximum at level of 150 mg kg^?1 cecropin, then those values no longer increased. Moreover, the dietary cecropin supplementation level also exhibited a decrease in the cumulative mortality rates compared with the controls when challenged with Aeromonas veronii. The results suggested that the dietary supplementation of cecropin could improve the growth, non‐specific immunity indicators and resistance of hybrid tilapia against A. veronii.     

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

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

Effect of DL‐methionine supplementation on the success of almost total replacement of fish meal with soybean meal in diets for hybrid tilapia (Oreochromis niloticus × Oreochromis mossambicus)

This study evaluated the effects of increasing levels of methionine (Met) supplementation on the success of almost total replacement of fish meal (FM) with soybean meal (SBM) in diets for hybrid tilapia (Oreochromis niloticus × Oreochromis mossambicus). Fish were fed for 70 days a FM‐based diet (Diet1‐positive control) or SBM‐based diets supplemented with graded levels of DL‐methionine (Diet2 to Diet7). Contrast in dietary Met, concentration was created by supplementing Diet2‐negative control with 1.2 (Diet3), 2.4 (Diet4), 3.6 (Diet5), 4.8 (Diet6) or 6.0 g kg^?1 (Diet7) of DL‐Met. Specific growth rate (SGR), feed conversion ratio (FCR), and protein gain and retention efficiency (PER) improved significantly with increasing levels of dietary DL‐Met supplementation. Moreover, nonlinear regression analysis of the effects of supplementing SBM‐based diet with graded levels of DL‐Met indicated that a dietary Met + Cys level of 15.7 and 12.5 g kg^?1 diet (as fed) was required to reach 95% of maximum weight and protein gain, respectively. Supplementation of SBM‐based diet with graded levels of DL‐Met proved an effective strategy in reducing FM content in practical diets for hybrid tilapia. Data also indicate that adjustment of dietary formulas according to currently recommended Met or Met + Cys dietary concentrations is probably limiting maximum growth potential of hybrid tilapia.     

Effect of dietary l‐methionine concentrations on growth performance,serum immune and antioxidative responses of juvenile Nile tilapia,Oreochromis niloticus

An 8‐week feeding trial was conducted to determine the effect of dietary l ‐methionine supplementation on growth performance, serum immune and antioxidative responses of juvenile Nile tilapia Oreochromis niloticus. Six iso‐nitrogenous (282 g kg^?1 crude protein) diets were formulated to contain graded levels of methionine (0.32%, 0.54%, 0.75%, 0.93%, 1.14% and 1.33% of dry weight) at a constant dietary cysteine level of 0.83 g kg^?1. Each diet was randomly assigned to triplicate groups of 25 juvenile fish (2.3 ± 0.0 g), which were fed three times daily (8:30, 12:30 and 17:00 hours). The results showed that growth performance and feed utilization significantly improved when dietary methionine levels increased (P < 0.05). Using quadratic regression analysis of weight gain against dietary methionine levels indicated that, the optimal dietary methionine requirement for maximum growth of juvenile tilapia was 9.12 g kg^?1 of the dry diet in the presence of 0.83 g kg^?1 cystine. In addition, maximum C4 content and lysozyme activity were observed in fish fed 7.50 g kg^?1 methionine diet; maximum C3 content and superoxide dismutase activity were obtained in fish fed 9.30 g kg^?1 dietary methionine level. While there was no significant difference in serum glutathione peroxidase activity among all methionine supplemented treatments (P > 0.05). Methionine supplementation decreased malondialdehyde content in serum significantly (P < 0.05) when compared with the control diet, while there was no significant difference among supplemented treatments. These data suggested that l ‐methionine affected antioxidant status and promoted serum immune response in juvenile Nile tilapia, and at non‐stressed status, the requirement of dietary methionine in maintaining normal immunity and physiology is lower than that for maximum growth.     

Effects of dietary protein and lipid levels with different protein‐to‐energy ratios on growth performance,feed utilization and body composition of juvenile red‐spotted grouper,Epinephelus akaara

An 8‐week feeding trial was conducted to assess dietary protein and lipid levels on growth performance, feed utilization and body composition of juvenile red‐spotted grouper (7.85 ± 0.03 g fish^?1). Nine semi‐purified diets were formulated containing varying protein levels (440–520 g kg^?1, dry matter) and lipid levels (60–120 g kg^?1, dry matter). The weight gain of juvenile Epinephelus akaara was affected by dietary protein (p = .005) and its interaction with dietary lipid (p = .020). Viscerosomatic index, intraperitoneal fat ratio and whole‐body lipid level increased with increasing dietary lipid level (p < .001). Nitrogen retention was not affected by dietary protein and lipid, while lipid retention decreased with increasing dietary lipid level (p < .001). The plasma blood urea nitrogen increased with increasing dietary protein level (p = .003). This study showed that diet with 520 g kg^?1 protein and 60 g kg^?1 lipid with 30.58 mg kJ^?1 P:E provided a maximal growth for this species. Moreover, an increase in dietary lipid levels (from 60 to 90 g kg^?1) could reduce the protein requirement (from 520 to 480 g kg^?1) without affecting the growth performance, while higher fat deposition was observed in fish fed high‐lipid diets.     

Dose‐dependent protective effects of dietary selenium on abalone Haliotis discus hannai Ino against the toxicity of waterborne copper

This study was designed to assess the protective effects of dietary selenium (Se) on abalone Haliotis discus hannai Ino against the toxicity of waterborne copper (Cu). A 60‐day feeding trial was conducted in a static water system for abalone (initial weight: 3.17 ± 0.01 g) exposed to 0.02 mg L^?1 of waterborne Cu. The animals were fed one of the three experimental diets with 0.10, 1.31 and 4.20 mg kg^?1 of Se from Na₂SeO₃·5H₂O respectively. Results showed that the abalone fed 1.31 mg kg^?1 of dietary Se had the lowest Cu concentration in shell, muscle, mantle, gill, hepatopancreas and serum. Meanwhile, the significant lowest contents of malondiadehyde and protein carbonyl in hepatopancreas were also found in the treatment with 1.31 mg kg^?1 of dietary Se (P < 0.05). In addition, this treatment had significant higher glutathione content and thioredoxin reductase activity in hepatopancreas (P < 0.05). However, the activity of Se‐dependent glutathione peroxidase (Se‐GPx) was significantly decreased in the treatment with 4.20 mg kg^?1 of dietary Se (P < 0.05). In this treatment, the protein carbonyl content in hepatopancreas was significantly higher than that in the group with 1.31 mg kg^?1 of dietary Se (P < 0.05). In conclusion, in terms of anti‐oxidation and Cu accumulation, the protective effects of dietary Se on abalone against waterborne Cu were dose‐dependent. The 1.31 mg kg^?1 of dietary Se had this effect, but not 4.20 mg kg^?1 of dietary Se. Moreover, the latter increased the oxidative stress in abalone exposed to the waterborne Cu.     

Aflatoxin B1 induced alterations in the stability of the lysosomal membrane in Oreochromis mossambicus (Peters, 1852)

This article elucidates the effect of crude dietary aflatoxin B₁ (AFB₁) on the stability of the lysosomal membrane in tilapia (Oreochromis mossambicus), and the analysis was made at the biochemical and cellular level. The liver lysosomal acid phosphatase activity was used to evaluate the functional integrity of the lysosome. Three experimental groups were fed on diets containing 0.375, 2.5 and 6 mg kg^?1 of AFB₁ for a time period of 6 weeks, whereas a fourth group fed on the semi‐purified diet formed the control. Significant changes were observed in the stability of the lysosomal membrane in aflatoxin exposed groups. This is the first report, so far, of changes induced by AFB₁ on the stability of lysosomal membrane in tilapia (O. mossambicus).     

Effect of fermented Enteromopha prolifera on the growth performance,digestive enzyme activities and serum non‐specific immunity of red tilapia (Oreochromis mossambicus × Oreochromis niloticus)

This study was conducted to evaluate the effect of dietary inclusion of different levels of fermented macroalga, Enteromorpha prolifera, on the growth performance, digestive enzyme activities and serum non‐specific immunity of red tilapia (Oreochromis mossambicus × Oreochromis niloticus). Fish were fed the control diet or the five diets supplemented with fermented E. prolifera for 7 weeks (diets 1–5 containing 10, 20, 30, 40 and 50 g kg^?1 of fermented E. prolifera respectively). The results showed that the percentage weight gain and specific growth rate (SGR) improved significantly in fish fed diets 3, 4 and 5, and regression analysis showed SGR reached the maximum in fish fed diet containing 37 g kg^?1 fermented E. prolifera, while the feed conversion ratio reduced significantly in fish fed diets 2, 3, 4 and 5, and regression analysis showed it reached its minimum in fish fed diet containing 41 g kg^?1 fermented E. prolifera. The pepsin, erepsin, gastric amylase, intestinal amylase, gastric lipase and intestinal lipase activities in fish fed diets 2, 3 and 4 were higher significantly than the control, with the exception of the pepsin activity in fish fed diet 4. The serum total superoxide dismutase, lysozyme, acid phosphatase and alkaline phosphatase activities enhanced significantly in fish fed diets 3 and 4. In conclusion, fermented E. prolifera had positive effects on the growth performance, digestive enzyme activities and serum non‐specific immunity of red tilapia and the recommended dose of fermented E. prolifera is 37–41 g kg^?1 in the diet of red tilapia.     

The effect of dietary methionine concentrations on growth performance of juvenile Nile tilapia (Oreochromis niloticus) fed diets with two different digestible energy levels

A growth trial was conducted to examine the effect of dietary digestible energy (DE) content on methionine (Met) utilization and requirement in juvenile Nile tilapia (Oreochromis niloticus). Ten iso‐nitrogenous (288 g kg^?1 protein) practical diets, with two DE levels (10.9 MJ kg^?1; 12.4 MJ kg^?1) and five methionine supplementation levels (0, 1, 2, 4 and 6 g kg^?1), were hand‐fed twice daily to triplicate groups of Nile tilapia (initial body weight 8.95 ± 0.06 g) for 8 weeks. Weight gain (WG) and specific growth rate (SGR) increased significantly with increasing dietary methionine concentration at the same DE content (P < 0.001). At the same dietary methionine level, WG and SGR of fish fed high‐DE diets were significantly higher than that of fish fed low‐DE diets (P = 0.0001), although no interaction was found between dietary DE and methionine supplementation. Based on quadratic regression analysis between dietary methionine concentration and weight gain, optimal methionine requirement for maximum growth, expressed as g Met required kg^?1 diet (low‐ versus high‐DE diets), increased as diet DE concentration increased (7.34 versus 9.90 g kg^?1 diet, respectively; with cysteine 4.70 g kg^?1 diet). The results indicated that diet DE content affects methionine utilization and requirement in juvenile Nile tilapia, fish fed high‐DE diets required more methionine for maximum growth.     

Dietary leucine requirement of Juvenile Nile tilapia,Oreochromis niloticus

An 8‐week feeding trial was conducted to evaluate the effects of dietary leucine on growth performance, feed utilization, body composition and non‐specific immune responses of juvenile Nile tilapia. Five isonitrogenous and isoenergetic diets were formulated to contain graded levels of L‐leucine (5.3, 8.1, 10.9, 13.2, 15.6 and 18.1 g kg^?1 diet, respectively) from dietary ingredients and crystalline L‐leucine. Each diet was randomly assigned to triplicate groups of 20 juvenile fish (1.94 ± 0.01 g) three times daily to apparent satiation. Results showed that the weight gain (WG) and specific growth rate (SGR) increased as dietary leucine concentrations increased from 5.3 to 13.2 g kg^?1 and then decreased slightly with further increase in dietary leucine concentrations. Quadratic regression analysis (y = ?522.6x² + 1304.x + 132.6, R² = 0.684) on weight gain against dietary leucine levels indicated that the optimal dietary leucine requirement was estimated to be 12.5 g kg^?1 diet (corresponding to 43.1 g kg^?1 of dietary protein). Leucine supplementation had no impact on the survival and body composition of tilapia. Serum lysozyme activity of fish fed diet containing 13.2 g kg^?1 leucine significantly increased compared to fish fed diet containing 5.3 g kg^?1. Serum superoxide dismutase activity and immunoglobulin M (IgM) concentration were not significantly affected by dietary leucine supplementation.     

Effects of dietary arginine on growth performance,feed utilization,haematological parameters and non‐specific immune responses of juvenile Nile tilapia (Oreochromis niloticus L.)

An 8‐week feeding trial was conducted to evaluate the effects of dietary arginine on growth performance, feed utilization, haematological parameters and non‐specific immune responses of juvenile Nile tilapia (6.03 g). Five isonitrogenous and isoenergetic diets were formulated to contain graded levels of L‐arginine (8.5 g kg^?1, 11.5 kg^?1, 15.3 kg^?1, 18.8 kg^?1 and 22.4 kg^?1 dry diet) from dietary ingredients and crystalline arginine. Each diet was randomly assigned to triplicate groups of 25 juvenile fish (6.04 ± 0.02 g) three times daily (8:30, 12:30, and 17:00 hours) to apparent satiation. Results showed that the weight gain (WG) and special growth rate (SGR) increased with increasing dietary arginine levels up to 15.3 kg^?1 and remained nearly the same thereafter. Arginine supplementation had no impact on the survival, body composition and haematological parameters of tilapia. However, the immune responses (plasma nitric oxide content, total nitric oxide synthase (T‐NOS) and lysozyme activity) significantly (P < 0.05) increased with increasing dietary argentine level after stress. Quadratic regression analysis (y = ?0.7147x² + 25.986x + 147.53 R² = 0.8736) on weight gain against dietary arginine levels indicated that the optimal dietary arginine requirement was estimated to be 18.2 kg^?1 of the diet (corresponding to 6.24% of dietary protein on a dry weight basis). The present study indicates that arginine has an immunostimulatory potential to help juvenile Nile tilapia cope with stress conditions such as Streptococcus iniae infection.     

The potential of dry olive cake in a practical diet for juvenile hybrid tilapia,Oreochromis niloticus × Oreochromis aereus

A feeding trial of 84 days was carried out to evaluate the effects of olive cake (OC) on growth, feed utilization, digestibility of nutrient, haematological values and some blood chemistry parameters of juvenile hybrid tilapia (Oreochromis niloticus × Oreochromis aereus). Four diets were prepared including OC at levels of 0, 120, 240 and 360 g kg^?1. Twenty fish per tank (initial weight 8.58 ± 0.09 g) were randomly distributed into 200‐L fibreglass tanks. Final body weight and specific growth rate of fish fed with diets OC12 were not significantly different compared to fish fed with the control diet. The best feed conversion rate and protein efficiency rate were obtained from the fish fed with the control and OC12 diets. Growth performance, feed conversion rate and protein efficiency rate of fish fed diets with OC incorporation levels of more than 12 per cent tended to decrease significantly (P < 0.05) compared to the control and OC12 diet groups. The apparent digestibility coefficients (ADC) of dry matter significantly decreased (P < 0.05) with the increase of dietary OC levels, whereas the ADC of protein was not affected by dietary treatment. The ADC of lipid of fish fed with control and OC12 diets were significantly (P < 0.05) higher than those of fish fed with OC24 and OC36 diets. Mean corpuscular haemoglobin, cholesterol and triglycerides were affected by dietary OC level. The findings of this study show that OC can be incorporated to diets of juvenile hybrid tilapia up to 120 g kg^?1 without any adverse effect on fish growth and feed utilization.     

Dietary taurine improves reproductive performance of Nile tilapia (Oreochromis niloticus) broodstock

This study was conducted to evaluate the effects of supplemental taurine on reproductive performance of Nile tilapia (Oreochromis niloticus) broodstock fed soybean meal‐based diets. Four isonitrogenous (350 g kg^?1 protein), isocaloric (18 MJ kg^?1) diets were formulated to contain 0, 5, 10 and 15 g kg^?1 taurine. The diets were fed to triplicate groups of juvenile Nile tilapia (10–15 g average body weight) at a female: male ratio of 3 : 1, to apparent satiation, three times per day for 130 days. The size at first maturation decreased with increasing dietary taurine to 10 g kg^?1 and levelled off with further taurine supplementation. The time to first spawning was also significantly shorter at 10 g kg^?1 taurine level. Spawning performances, including spawning frequencies, total number of spawnings per tank, number of spawnings per female and absolute fecundity, were all significantly improved with increasing dietary taurine up to 10 g kg^?1. However, the quadratic regression analyses indicated that the maximum spawning performance occurred at 8 g kg^?1 of supplemental taurine. Eggs produced from broodstock fed 10 g kg^?1 taurine exhibited significantly higher hatchability and required shorter time for hatching and yolk‐sac absorption and also resulted in higher larval weight than at other dietary taurine levels. The highest egg protein, total amino acids and taurine were also obtained at 10 g kg^?1 taurine. These results suggest that 8 g kg^?1 dietary taurine is required for optimum reproductive outputs of Nile tilapia broodstock.     

Effects of extruded and pelleted diets with differing lipid levels on growth,nutrient retention and serum biochemical indices of tilapia (Oreochromis aureus × Tilapia nilotica)

This study was conducted to evaluate the effects of extruded diets and pelleted diets with varying dietary lipid levels on growth performance and nutrient utilization of tilapia. Six diets, containing three levels of lipid at 40, 60 or 80 g kg^?1 (with the supplemental lipid of 0, 20 or 40 g kg^?1, respectively), were prepared by extruding or pelleting and then fed to tilapia juveniles (8.0 ± 0.1 g) in cages (in indoor pools) for 8 weeks. The results indicated that the fish that were fed the diet with 60 g kg^?1 of lipid had a higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), lipid retention (LRE), energy retention (ERE), apparent protein digestibility, apparent dry matter digestibility and a lower feed conversion ratio (FCR) than those fed the diet with 40 g kg^?1 lipid in both the extruded diet and pelleted diet (P < 0.05). As the dietary lipid level increased from 60 to 80 g kg^?1, these parameters were not further improved, even digestibilities of the crude protein and dry matter decreased (P < 0.05). With the dietary lipid level increased, whole‐body lipid content significantly increased (P < 0.05), serum aspartate aminotransferase, alkaline phosphatase, total cholesterol and low‐density lipoprotein cholesterol (LDL‐C) tended to increase (P > 0.05), whereas whole‐body protein content, serum triglyceride (TG), high‐density lipoprotein cholesterol (HDL‐C) and HDL‐C/LDL‐C tended to decrease (P > 0.05). Fish fed with the extruded diets had a higher WG, SGR, hepatosomatic index (HSI), PER, protein retention (PRE), LRE, ERE, TG, apparent digestibility of protein and dry matter, as well as a lower FCR, than those fed with the pelleted diets at the same dietary lipid level (P < 0.05). These results suggested that tilapia fed with the extruded diets had a better growth and higher nutrient utilization than fish fed with the pelleted diets, when dietary lipid level ranged from 40 to 80 g kg^?1 and at dietary crude protein level was 280 g kg^?1. The optimum dietary lipid level was 60 g kg^?1 in both the pelleted and extruded diets, and extrusion did not affect dietary lipid requirement of the tilapia.     

Improvement of growth and antioxidant status in Nile tilapia,Oreochromis niloticus,fed diets supplemented with mushroom stalk waste hot water extract

Mushroom stalk waste (MSW) generated from the oyster mushroom industry is drastically increasing and safe disposal of MSW is becoming a critical issue worldwide. Mushrooms are an established, excellent source of nutraceuticals and antioxidants, and therefore MSW may confer similar effects when consumed. The severe deterioration of aquatic habitat may compromise the homoeostasis of antioxidative metabolism of Nile tilapia, Oreochromis niloticus, which resulted in a reduced total production. Based on this paradigm, hot water extracts (HWE, 2‐ and 5‐h) of MSW were evaluated as a supplement in fish feed and determined the effect on growth performance and the antioxidant status of Nile tilapia, O. niloticus, in vivo. The HWE 5‐h contained significantly higher amounts of nutrient and β‐glucan than HWE 2‐h (P < 0.05). Four standardized in vitro antioxidant assays showed that HWE 5‐h was a better antioxidant agent than HWE 2‐h (P < 0.05). Tilapia fingerlings fed 5 g kg^?1 HWE supplemented feed produced better (P < 0.05) growth and higher antioxidant enzyme activities than 10 g kg^?1 HWE, CD and BD. Thus, HWE of MSW included at 5 g kg^?1 may be beneficial to tilapia farming and may also provide a way of disposing the waste created by mushroom farming.     

Effect of dietary vitamin B6 on growth,feed utilization,health and non‐specific immune of juvenile Pacific white shrimp,Litopenaeus vannamei

Six diets were formulated with vitamin B₆ levels (2.6, 32.7, 54.8, 90.7, 119.6 and 247.4 mg kg⁻¹, dry diet) to determine the requirement for juvenile Pacific white shrimp, Litopenaeus vannamei. Triplicate groups of 40 juvenile shrimp (approximately 1.0 g) were provided four times each day to apparent satiation (8 weeks). Weight gain (WG), specific growth rate, feeding efficiency, protein efficiency ratio (PER) and protein productive value of the shrimp were significantly influenced by the vitamin B₆ levels. No significant differences in whole‐body and muscle composition, except for dry matter and protein contents in whole body. Vitamin B₆ concentration in the hepatopancreas significantly increased with the dietary vitamin B₆ level increasing from 2.6 to 32.7 mg kg⁻¹. High‐density lipoprotein cholesterol in the haemolymph improved with the dietary vitamin B₆ levels increasing from 2.6 to 90.7 mg kg⁻¹ diet and no significant differences in low‐density lipoprotein cholesterol, cholesterol, glucose and total protein concentrations. Aspartate aminotransferase, alanine aminotransferase, superoxide dismutase, catalase and lysozyme in the haemolymph were significantly influenced by dietary vitamin B₆ levels. The optimal dietary vitamin B₆ requirements estimated using a two‐slope broken‐line model based on WG and SGR and an exponential model based on the vitamin B₆ concentration in the hepatopancreas were 110.39, 110.08 and 167.5 mg kg⁻¹, respectively.     

Dietary thiamin could improve growth performance,feed utilization and non‐specific immune response for juvenile Pacific white shrimp (Litopenaeus vannamei)

This study evaluated the effect of dietary thiamin on growth performance, feed utilization and non‐specific immune response for juvenile Pacific white shrimp, Litopenaeus vannamei. Six isonitrogenous and isolipidic practical diets were formulated with graded thiamin levels of 6.9, 32.7, 54.2, 78.1, 145.1 and 301.5 mg kg^?1 of dry diet, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile shrimp and provided four times each day to apparent satiation. Weight gain (WG) and specific growth rate (SGR) of the shrimp were significantly influenced by the dietary thiamin levels, the maximal WG and SGR occurred at 54.2 mg kg^?1 dietary thiamin level. However, with further increase in dietary thiamin level from 54.2 to 301.5 mg kg^?1, the WG and SGR significantly decreased. Shrimp fed the 54.2 mg kg^?1 thiamin diet exhibited higher feed efficiency, protein efficiency ratio and protein productive value than those fed the other diets. Dry matter and protein content in whole body were significantly affected by the dietary thiamin levels. Thiamin concentration in hepatopancreas significantly increased when the dietary thiamin level increased from 6.9 to 145.1 mg kg^?1. The total protein, glucose, triacylglycerol and cholesterol contents in hemolymph were not significantly affected by the dietary thiamin levels. Dietary thiamin had significantly influenced superoxide dismutase, catalase and lysozyme activities in hemolymph. Results of this study indicated that the optimal dietary thiamin requirements estimated using a two‐slope broken‐line model based on WG and thiamin concentration in hepatopancreas were 44.66 and 152.83 mg kg^?1, respectively.     

Evaluating fungi‐degraded date pits as a feed ingredient for Nile tilapia Oreochromis niloticus L.

Five isocaloric‐isonitrogenous diets containing 0, 150, 300, 450 and 600 g kg^?1 of fungi Trichoderma reesei‐degraded date pits (DDP), as a replacement for dietary corn, were fed to triplicate groups of Nile tilapia Oreochromis niloticus L. fingerlings (1.88 g initial weight), for 9 weeks, in 70 L fibreglass tanks. Each tank was considered as an experimental unit and was part of a water recirculating system utilizing filtered and aerated ground well water (24 ± 3 °C). Tilapia growth performance, namely, weight gain, feed conversion, specific growth rate and protein efficiency ratio were similar and superior in fish fed diets containing 150 and 300 g kg^?1 DDP, when compared with those fish fed the other diets. Fish fed the control diet with 450 g kg^?1 DDP had better growth efficiency performance than those fed diets containing 0 and 600 g kg^?1. Fish fed the diet with 600 g kg^?1 DDP were inferior to all other groups. Tilapia body composition was affected by increasing DDP level in the diets as body fat was decreased, while body moisture was increased. In conclusion, DDP could replace 300 g kg^?1 of dietary corn with better growth results. Further increase of date pits replacements to 450 g kg^?1 will affect growth performance, when compared with the control.     

Dietary Lactobacillus plantarum supplementation decreases tissue lead accumulation and alleviates lead toxicity in Nile tilapia (Oreochromis niloticus)

Pollution by the heavy metal lead (Pb) has become a threat to both aquaculture and food safety. In this study, the protective effects of a selected probiotic with good Pb binding capacity (Lactobacillus plantarumCCFM8661) against waterborne Pb exposure were evaluated in Nile tilapia (Oreochromis niloticus). One hundred and eighty fish were divided into four groups as control, Pb‐only, Pb‐plus‐CCFM8661 and CCFM8661‐only. Fish were exposed to a dose of waterborne Pb level at 1 mg L^?1 for 4 weeks, and the probiotic was administered at 10⁸ CFU g^?1 in fish diet twice daily. The results showed that dietary supplementation of CCFM8661 ameliorated the growth performance and prevented the death of Pb‐exposed fish. Cotreatment with Pb and CCFM8661 also effectively decreased Pb accumulation in kidney, liver, gonad, brain, gills and muscle. Moreover, the administration of this probiotic alleviated Pb‐induced oxidative stress, recovered digestive enzyme activities and blood δ‐aminolevulinic acid dehydratase activity, reversed alterations in innate immune status and decreased the frequencies of the nuclear abnormalities in peripheral blood erythrocytes of fish. These results suggested that CCFM8661 may be a novel dietary supplement against Pb toxicity at least in tilapia.