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1.
Threonine is the third‐limiting essential amino acid in diets based on cereal ingredients. A 4‐week trial was conducted to determine the threonine requirement of large Nile tilapia based on fish growth, feed efficiency, body composition, protein and amino acid retention. Six hundred fish (563.3 ± 15.1 g) were distributed into twenty 1.2‐m3 cages. Five diets containing 288 g kg?1 of crude protein, 12.7 MJ kg?1 of digestible energy and 8.9, 10.5, 12.2, 13.7 and 15.4 g kg?1 of threonine were elaborated. Fish were hand‐fed five times a day to extruded diets. Significantly, differences in growth performance and amino acids retention among the treatments were observed. Fish fed 10.5 g kg?1 of threonine showed higher daily weight gain, gutted weight and fillet weight (P < 0.05) compared to fish fed with other experimental diets. Diets containing 8.9–15.4 g kg?1 of threonine did not affect whole body and muscle proximate composition. Based on second‐order regression analysis, the dietary threonine requirement estimated based on final gain, fillet weight and fillet yield was 12, 12.1 and 11.5 g kg?1 diet, respectively. The dietary threonine requirement for maximum fillet yield of Nile tilapia was estimated to be 11.5 g kg?1.  相似文献   

2.
Twelve experimental diets (D‐1 to D‐12) in a 4 × 3 factorial design (four protein levels: 250, 350, 400 and 450 g kg?1 and three lipid levels: 50, 100 and 150 g kg?1) were formulated. Carbohydrate level was constant at 250 g kg?1. Rohu fingerlings (average wt. 4.3 ± 0.02 g) were fed the experimental diets for 60 days in three replicates at 2% BW  day?1. Weight gain (%), specific growth rate (% day?1) and feed gain ratio (FGR) indicated that diets containing 450 g kg?1 protein and 100 or 150 g kg?1 lipid (diets D‐11 and D‐12) resulted in best performance, although results were not significantly different from those of diet D‐9 (400 g kg?1 protein and 150 g kg?1 lipid). Protein efficiency ratio was highest with diets D‐6 (350 g kg?1 protein and 150 g kg?1 lipid) and D‐9 (400 g kg?1 protein and 150 g kg?1 lipid) (P > 0.05) and declined with higher and lower protein diets at all levels of lipid tested. Elevated lipid level (50, 100 or 150 g kg?1) did not produce better FGR in diets containing 400 and 450 g kg?1 dietary protein (P > 0.05). The combined effects of protein and lipid were evident up to 400 g kg?1 protein. Growth and FGR showed consistent improvement with increased lipid levels from 50 to 150 g kg?1 at each protein level tested except with diets containing 450 g kg?1 protein. Apparent nutrient digestibility (for protein, lipid and energy) did not show significant variation among different dietary groups (P > 0.05). Whole body protein and lipid contents increased significantly (P > 0.05) with dietary protein level. The results of this study indicate that rohu fingerlings are adapted to utilize high protein in diets with varying efficiency. The fish could utilize lipid to spare protein but there is no significant advantage from this beyond the dietary protein level of 350–400 g kg?1 in terms of growth and body composition.  相似文献   

3.
Effects of temperature and processing on the stability of a commercial protease were assessed in an in vitro trial followed by growth trials with white shrimp and tilapia. Results showed that the protease has a high heat stability against pelleting, and it could hydrolyse dietary proteins during feed processing. In Exp. 2, white shrimp (3.3 g) fed low fish meal (FM) diet (LFD) with protease addition had similar growth to that fed high fish meal diet, and both had higher weight gain (WG) and lower feed conversion ratio (FCR) than that fed LFD without protease addition (P < 0.05). In Exp. 3, compressed (CD) or extruded (ED) diets containing 30 g kg?1 or 90 g kg?1 FM were supplemented with or without protease and then fed to tilapia (1.7 g) for 8 weeks. WG was improved and FCR decreased (P < 0.05) by the supplementation of protease in 30 g kg?1 FMCD, but not in 90 g kg?1 FMCD and ED diets when compared to those diets without protease supplementation. The digestibility trial with CD indicated the improved apparent digestibilities of dry matter and crude protein by dietary protease in 30 g kg?1 FMCD, but not in 90 g kg?1 FMCD. Results above showed that the protease has a high heat stability and the supplementation of protease in CD with low FM level can improve the growth of shrimp and tilapia.  相似文献   

4.
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.  相似文献   

5.
An 8‐week feeding trial was conducted to investigate the optimum dietary protein and lipid levels for growth, feed utilization and body composition of Pseudobagrus ussuriensis fingerlings (initial weight: 3.40 ± 0.01 g). Twelve diets containing four protein levels (350, 400, 450 and 500 g kg?1 crude protein) and three lipid levels (50, 100 and 150 g kg?1 crude lipid) were formulated. Fish were randomly allotted to 36 aquaria (1.0 × 0.5 × 0.8 m) with 25 fish to each glass aquarium. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. The results showed that weight gain and specific growth rate (SGR) decreased with increasing dietary lipid level from 50 to 150 g kg?1 at the same dietary protein level. Fish fed the diets containing 150 g kg?1 lipid exhibited higher feed conversion ratio (P < 0.05), lower protein efficiency ratio (PER) and nitrogen retention efficiency (NRE) relative to fish fed the diet containing 50 and 100 g kg?1 lipid. Weight gain and SGR significantly increased with increasing dietary protein from 350 to 450 g kg?1 at the same dietary lipid level, and even a little decline in growth with the further increase in dietary protein to 500 g kg?1. Daily feed intake, NRE and PER were significantly affected by both dietary protein and lipid levels (P < 0.05) and tended to decrease with increasing dietary protein and lipid levels. Whole‐body protein content increased as protein levels increased and lipid levels decreased. Whole‐body lipid and muscle lipid content increased with increasing dietary lipid level, and decreased with increasing dietary protein at each lipid level. There was no significant difference in condition factor and viscerosomatic index among fish fed the diets. Hepatosomatic index was affected by dietary lipid level (P < 0.05), and increased with increasing dietary lipid level at the same protein level. These results suggest that the diet containing 450 g kg?1 protein and 50 g kg?1 lipid with a P/E ratio of 29.1 mg protein kJ?1 is optimal for growth and feed utilization of P. ussuriensis fingerlings under the experimental conditions used in the study.  相似文献   

6.
Critical to the development of a cost‐effective feed for the tropical spiny lobster Panulirus ornatus is knowledge of its response to the protein and lipid (or energy) content of the feed. An experiment of 12 weeks duration was carried out to examine growth responses of juvenile lobsters to pelleted diets that provided six crude protein (CP) levels [320–600 g kg?1 dry matter (DM)] and two lipid levels (nominally 60 and 100 g kg?1 DM). Lobsters (mean initial weight of 1.8 g) were held in groups of nine or 10 animals in 24 × 350 L tanks, fed twice daily at a restricted level, and maintained at 28 °C. Maximal growth responses occurred at dietary CP contents of 474 g kg?1 for the 60 g kg?1 lipid series and 533 g kg?1 for the 100 g kg?1 lipid series. A second experiment, of 4 weeks duration, compared two dietary treatments: a mixture of two of the best diets from the first experiment, and a commercial shrimp (Penaeus japonicus) feed. Lobsters were held under the same experimental conditions as in the first experiment, but were fed to excess twice daily. Their growth was significantly greater (P < 0.05) on the shrimp feed (0.68 g week?1) than on the laboratory‐pelleted diets used in the main study (0.32 g week?1). The results indicate that the optimal dietary protein and lipid content of the diet for P. ornatus is about 530 and 100 g kg?1, respectively.  相似文献   

7.
A feeding trial was conducted in a recycling water system during 10 weeks to determine the optimal protein to lipid ratio in Asian red‐tailed catfish (Hemibagrus wyckioides). Six diets of two protein levels (390 and 440 g kg?1) with three lipid levels (60, 90 and 120 g kg?1) were formulated. Fish (1.96 g) were fed six diets with four replicates to apparent satiation at a stocking density of 50 fish per tank (500 L). Faeces were collected in cultured tanks at the end of the feeding trial for digestibility measurement. Significantly, improved growth performances (P < 0.01) and higher feed utilization (P < 0.001) were observed in fish fed with higher lipid diets. However, higher protein diets did not significantly improve fish growth but they reduced FCR (P < 0.001) and protein efficiency ratio (P < 0.01). Higher lipid diets also resulted in significantly increased adipose‐somatic index, carcass fat and reduced moisture of the fish. The study revealed the protein sparing effect of dietary lipid in the catfish and highest growth performance was found by fish fed 390 g kg?1 protein and 120 g kg?1 lipid diet with P/E ratio of 20.48 mg protein kJ?1. DP/DE ratio for maximal growth rate in diets was 21.48 mg protein kJ?1.  相似文献   

8.
A feeding trial was conducted to study the effect of dietary lipid on growth performance and heat‐shock protein (HSP70 and HSP60) response of white seabass (WSB), Atractoscion nobilis. Five diets were formulated to contain 440 g kg?1 protein from 300 g kg?1 fish meal, 240 g kg?1 soybean meal and 100 g kg?1 soy protein concentrate with different levels of lipid: 100, 120, 140, 160 or 180 g kg?1. At the end of the trial, heat shock response based on HSP70 and HSP60 was measured in liver and white muscle from fish at ambient temperature and temperature shock conditions. Final weight and percent gain were significantly higher for fish fed the 100 g kg?1 lipid diet than for fish fed the rest of the diets (P ≤ 0.05). Feed conversion ratio was lowest for fish fed the 100 g kg?1 lipid diet. The HSP70 and HSP60 responses were positively correlated to dietary lipid levels following temperature shock. At ambient temperature, HSP60 and HSP70 responses in muscle and HSP60 response in liver increased with dietary lipid level. Temperature shock significantly increased the HSP response of fish in all treatments. Results of this study demonstrated that a moderate (110–120 g kg?1) level of dietary lipids would be recommended for production diets but a higher dietary lipid level may be required for optimal stress tolerance.  相似文献   

9.
A 63‐day growth trial was undertaken to estimate the effects of supplemented lysine and methionine with different dietary protein levels on growth performance and feed utilization in Grass Carp (Ctenopharyngodon idella). Six plant‐based practical diets were prepared, and 32CP, 30CP and 28CP diets were formulated to contain 320 g kg?1, 300 g kg?1 and 280 g kg?1 crude protein without lysine and methionine supplementation. In the supplementary group, lysine and methionine were added to formulate 32AA, 30AA and 28AA diets with 320 g kg?1, 300 g kg?1 and 280 g kg?1 dietary crude protein, respectively, according to the whole body amino acid composition of Grass Carp. In the groups without lysine and methionine supplementation, weight gain (WG, %) and specific growth rate (SGR, % day?1) of the fish fed 32CP diet were significantly higher than that of fish fed 30CP and 28CP diets, but no significant differences were found between 30CP‐ and 28CP‐diet treatments. WG and SGR of the fish fed 32AA and 30AA diets were significantly higher than that of fish fed 28AA diets, and the performance of grass carp was also significantly improved when fed diets with lysine and methionine supplementation (P < 0.05), and the interaction between dietary protein level and amino acid supplementation was noted between WG and SGR (P < 0.05). Feed intake (FI) was significantly increased with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05), but feed conversion ratio (FCR) showed a significant decreasing trend (P < 0.05). Two days after total ammonia nitrogen (TAN) concentration test, the values of TAN discharged by the fish 8 h after feeding were 207.1, 187.5, 170.6, 157.3, 141.3 and 128.9 mg kg?1 body weight for fish fed 32CP, 32AA, 30CP, 30AA, 28CP and 28AA diets, respectively. TAN excretion by grass carp was reduced in plant‐based practical diets with the increase in dietary protein level and the supplementation of lysine and methionine (P < 0.05). The results indicated that lysine and methionine supplementation to the plant protein sources‐based practical diets can improve growth performance and feed utilization of grass carp, and the dietary crude protein can be reduced from 320 g kg?1 to 300 g kg?1 through balancing amino acids profile. The positive effect was not observed at 280 g kg?1 crude protein level.  相似文献   

10.
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.  相似文献   

11.
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.  相似文献   

12.
This study was conducted to evaluate the effects of dietary taurine on growth performance and feed utilization of Nile tilapia (Oreochromis niloticus) larvae. Four plant protein‐based, isonitrogenous (400 g kg?1 protein), isoenergetic (19 MJ kg?1) diets supplemented with four taurine concentrations (0.0, 5.0, 10.0 and 15.0 g kg?1; designated as T0, T0.5, T1 and T1.5, respectively) were prepared. The diets were fed to triplicate groups of fish larvae (0.024 g average body weight), to apparent satiation, three times per day for 60 days. Larval growth rates and feed utilization efficiency were significantly improved with increasing supplemental taurine up to 10 g kg?1 and decreased with further taurine supplementation. The quadratic regression analyses indicated that the maximum larval performance occurred at about 9.7 g kg?1 of total dietary taurine. Fish survival was significantly lower at 15 g kg?1 dietary taurine than at other taurine levels. Body protein significantly increased, while body moisture and ash decreased, with increasing dietary taurine up to 10 g kg?1 and decreased with further taurine supplementation to 15 g kg?1. Body lipid was not significantly affected by dietary taurine concentration. A number of body amino acids (tryptophan, arginine, histidine, leucine, isoleucine, valine, alanine, glycine, threonine and taurine) significantly increased with increasing supplemental taurine up to 10 g kg?1 and then decreased with further increase in dietary taurine levels. The rest of body amino acids were not significantly affected by dietary taurine. The present results suggest that about 9.7 g kg?1 dietary taurine is required for optimum performance of Nile tilapia larvae fed soybean meal‐based diets.  相似文献   

13.
A 76‐day feeding trial was carried out to evaluate the effects of Lysine and Methionine supplementation on growth and digestive capacity of grass carp (Ctenopharyngodon idella) fed plant protein diets using high‐level canola meal (CM). Fish with initial average weight 103.9 ± 0.6 g were fed three extruded diets. Fish meal (FM) diet was formulated as the normal control with 40 g kg?1 FM and 300 g kg?1 CM; CM diet was prepared by replacing all FM with CM (total 340 g kg?1) without Lys or Met supplementation; CM supplement (CMS) diet was similar to CM diet but was supplemented with essential amino acids (EAA) to ensure the levels of Lys and Met similar to those in the FM diet. Feed intake, feed efficiency and specific growth rate of the grass carp fed CMS and FM diets were similar (P > 0.05), but higher than those of the grass carp fed CM diet (P < 0.05). The hepatosomatic index, relative gut length, intestosomatic index and intestinal folds height were significantly improved in fish fed FM and CMS diets as compared to CM diet (P < 0.05). Lower activities of trypsin, lipase and amylase in hepatopancreas were observed in fish fed CM diet (P < 0.05). Three hundred and forty gram per kilogram CM without Lys or Met supplementation significantly decreased trypsin, lipase and amylase mRNA levels in hepatopancreas (P < 0.05). These results indicated that the high supply of CM (340 g kg?1) in plant protein (200 g kg?1 soybean meal and 100 g kg?1 cottonseed meal) diets decreased digestive ability through decreasing digestive enzyme activities and enzyme gene's expressions of grass carp, and these side effects can be reversed by supplementing Lys and Met. Therefore, CM could be high level used in a plant protein blend‐based extruded diet for grass carp as long as EAA were supplemented.  相似文献   

14.
An 8‐week feeding trial was conducted to evaluate the effects of replacing plant proteins with rubber seed meal (RSM) on growth, nutrient utilization and blood biochemical parameters of juvenile tilapia (Oreochromis niloticus × O. aureus). Five experimental diets were formulated with 0, 65, 130, 195 and 260 g kg?1 RSM replacing graded levels of a mixture of plant proteins, respectively. Dietary RSM inclusion level up to 260 g kg?1 did not affect growth and feed utilization. Fish fed diets with 65–130 g kg?1 RSM showed the highest feed efficiency ratio and protein efficiency ratio. However, high inclusion of RSM (260 g kg?1) markedly reduced the hepatic protease, lipase and amylase activities, and thereby decreased the dry matter and crude protein digestibilities. Similarly, plasma superoxide dismutase and glutathione reductase activities were depressed by high inclusion of RSM. These results indicate that dietary RSM inclusion level up to 195 g kg?1 did not affect the growth and health status of tilapia, whereas a further inclusion of RSM might result in reduced feed digestibility and antioxidant capacity of tilapia.  相似文献   

15.
The aim of the present work was to obtain the lipid utilization of Octopus vulgaris supplying formulated semi‐moist diets with different contents in cod oil (reduced from water content): 0 g kg?1 (A0, 138 g kg?1 lipids DW; N = 4), 100 g kg?1 (A100, 286 g kg?1 lipids DW; N = 6) and 200 g kg?1 (A200, 388 g kg?1 lipids DW; N = 6). The rest of the ingredients were constant in the three diets: 200 g kg?1 gelatin, 100 g kg?1 egg yolk powder, 150 g kg?1 freeze‐dried Todarodes sagittatus and 50 g kg?1 freeze‐dried Sardinella aurita). Survival was 100% with the three diets. The highest absolute feeding (15.8 ± 1.2 g day?1), growth (9.6 ± 1.4 g day?1; 0.91% BW day?1) and feed efficiency rates (60.3%) were obtained with diet A0. This diet also showed greater retention of lipid and protein than A100 and A200. Protein digestibility was above 95% in all of the diets. Only diet A0 led to a high lipid digestibility coefficient (81.25%), which fell drastically to 12.3% in A200. It was notable the high polar lipid digestibility rates (83–89%) respect to neutral lipids (2–87%) in all diets. The best results were obtained with lipid feeding rates of around 1 g day?1 and a suitable lipid content on 130–140 g kg?1 DW in formulated diets for O. vulgaris.  相似文献   

16.
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.  相似文献   

17.
A 126‐day experiment was carried out under controlled conditions to compare the effects of five levels (0.5, 1.0, 1.5, 2.0 and 2.5 g kg?1) of dietary nucleotide (Vannagen®) on the growth performance and biological indices of juvenile crayfish (8.25 ± 0.39 g). The protein efficiency ratio (PER, 1.69–2.17), lipid efficiency ratio (LER, 2.29–3.00), energy efficiency ratio (EER, 2.68–3.65), protein productive value (PPV, 57.01–68.95%), lipid productive value (LPV, 63.02–75.15%) and energy productive value (EPV, 68.20–88.15%) increased significantly (P < 0.05) as linear response to increased dietary nucleotide from 0.5 to 2.5 g kg?1 in the feed. With an increase in the dietary nucleotide, the uricase activity (654.29–827.63 U g?1) and lactobacillus count to total count ratio (1.21–2.17) of crayfish fed the experimental diets increased significantly (P < 0.05). Crayfish fed the diets containing different levels of nucleotide (from 0.5 to 2.5 g kg?1) had higher phenoloxidase activity (1.57–2.11 U min?1) than that of control after air exposure challenge. At the levels tested, 2 g kg?1 nucleotide in the diet was considered optimum for growth performance, digestibility and immune responses. It can be concluded that dietary nucleotide exerted positive effects on growth performance, feed utilization and accelerate crayfish immune response against air exposure challenge.  相似文献   

18.
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.  相似文献   

19.
W. Li  X. Wen  Y. Huang  J. Zhao  S. Li  D. Zhu 《Aquaculture Nutrition》2017,23(5):1035-1047
A two‐factor experiment was designed to determine the suitable dietary protein and lipid levels for juvenile Nibea diacanthus. Nine extruded pellet diets were formulated to contain three levels of protein (420, 470 and 520 g kg?1) and three levels of lipid (70, 110 and 150 g kg?1). Each diet was randomly fed to triplicate groups of 25 juvenile N. diacanthus (initial weight 12.12 ± 0.23 g) for 8 weeks in net cages. The results showed that weight gain rate (WGR), specific growth rate, final body weight and energy retention were significantly influenced by the dietary protein and lipid levels‐. The highest WGR (982.5g kg?1.) of N. diacanthus was found in the group with dietary protein and lipid of 520 and 150 g kg?1. Feed intake and feed efficiency were significantly impacted by the dietary protein levels. An interactive effect between dietary protein and lipid on the protein retention and protein efficiency ratio was observed. There were no significant differences in condition factor and survival among all treatments. Hepatosomatic index and viscerasomatic index of N. diacanthus were positively related with dietary lipid levels, but negatively with dietary protein levels. Crude protein, crude lipid, ash, moisture and energy contents of the whole body, muscle and liver were influenced by dietary protein and lipid levels. Moreover, total essential amino acid pattern of the muscle was correlated to those of dietary protein. Total protein concentration in the serum was affected by dietary protein and lipid levels. Meanwhile, both serum cholesterol and triglyceride concentrations increased with increasing dietary lipid levels. These results demonstrate that the diet containing 470 g kg?1 protein and 110 g kg?1 lipid is optimal for juvenile N. diacanthus and analysis of WGR by quadratic regression indicated that the estimated optimal protein‐to‐energy ratio for juvenile N. diacanthus was 24.53 mg protein kJ?1.  相似文献   

20.
This study evaluated the effects of soy protein ratio, lipid content and the minimum dietary level of krill meal in plant‐based diets over the growth performance and digestibility of Litopenaeus vannamei. Nine plant‐based diets varied the soybean meal (SBM) and soy protein concentrate (SPC) inclusion ratio at 1 : 2.3, 1 : 1 and 2.5 : 1, and their dietary lipid content at 121.4 ± 9.4, 102.3 ± 1.2, and 79.9 ± 1.2 g kg?1 (in a dry matter basis). An additional diet containing 120 g kg?1 of fish meal (salmon by‐product) was used as a control. Krill meal was included at 0, 5, 10, 20 and 30 g kg?1 in a new set of plant‐based diets. After 10 weeks in clear‐water tanks of 0.5 m3, no effect of SBM:SPC ratio and dietary lipid content was detected on shrimp survival. However, dietary lipid levels of 80 and 121 g kg?1 combined with a high SPC to SBM resulted in the lowest final body weight and the poorest apparent crude protein digestibility, respectively. Krill meal increased feed intake at only 10 g kg?1, while at 20 g kg?1, it accelerated shrimp growth, increased yield and reduced food conversion ratio.  相似文献   

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