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1.
To determine the dietary β‐glucan and vitamin C levels that would enable the fish to cope with different stress, 252 tilapia (16.86 ± 0.24 g) were distributed in thirty six 250‐L aquaria and fed experimental diets for 60 d. Diets were supplemented with β‐glucan (0.1, 0.2, 0.4, and 0.8%) and vitamin C (400 and 600 mg/kg diet) and distributed in a factorial design that included a control diet (0 β‐glucan/125 mg vitamin C/kg). After growth performance analyses, a group of 108 fish were subjected to cold‐induced stress and another to Aeromonas hydrophila infection. Hematological and immunological parameters were determined before and after the stress. Growth performance was not affected. Red blood cells, hematocrit, mean corpuscular volume, total plasma protein, albumin : globulin ratio and leukocytes, lymphocytes, neutrophils, and monocytes were affected (P < 0.05) by stress and/or diets. The control diet resulted in higher post‐infection cortisol (P < 0.05). Liver vitamin C was directly proportional to dietary vitamin C (P < 0.05). The production of hydrogen peroxide and nitric oxide was also affected by diets and/or bacterial challenge (P < 0.05). In total, 0.1–0.2% β‐glucan and 600 mg/kg vitamin C increased fish resistance to stress and 0.8% β‐glucan resulted in reduced immune responses regardless of the vitamin C supplementation level.  相似文献   

2.
The effects of distiller's dried grains with solubles (DDGS) from different sources on growth performance, hematology, and immunity of hybrid tilapia, Oreochromis niloticus × Oreochromis aureus, were evaluated. Sex‐reversed, all‐male hybrid tilapia (3.72 ± 0.08 g initial weight) were fed diets in which 30% of protein in the control diet, supplied by a combination of soybean meal (SBM) and corn meal (CM) (SBM : CM ratio = 1.8), was replaced by wheat DDGS (WtDDGS), sorghum DDGS (SDDGS), whiskey DDGS (WkDDGS), or one of three corn DDGS (CDDGS 1–3) sources (control and six experimental diets) for 10 wk. Tilapia were stocked at 30 fish per aquaria (three aquaria per diet). Growth of tilapia fed diets containing DDGS sources was similar to or better than the control diet, and no nutritional deficiencies were observed. Tilapia fed the CDDGS 2 and 3 sources showed superior weight gain. Improved growth appeared to be caused by an increase in feed intake and not due to improvements in dietary nutritional value. Hematology and immunity were not affected by DDGS source. It is concluded that DDGS from all the sources examined can be included in the diet of juvenile hybrid tilapia at about 30% as a replacement of one‐third protein from SBM‐CM mixture without adverse effects.  相似文献   

3.
This study was conducted to evaluate the effects of probiotic‐amended diets fed to juvenile Nile tilapia, Oreochromis niloticus, on growth and susceptibility to Streptococcus iniae infection. Fish (average weight 16.5 ± 0.2 g) were fed five diets formulated with Bacillus subtilis strains SB3086, SB3295, SB3615, or AP193 either individually or in combination of strains SB3086 and SB3615 at a targeted concentration of approximately 4 × 107 colony‐forming units (CFU)/g of feed or with a basal control diet with no additives for 21 d. After the 21‐d growth trial, no significant difference in growth performance was observed with any probiotic‐amended diet. Results from serum bactericidal activity showed a significant difference between treatments and the control (P = 0.0002), except for the SB3295‐amended diet (P = 0.9020). Lysozyme activity was also significantly different in fish fed probiotic diets from those fed control diet (P = 0.0001). After 21 d of feeding, fish were challenged with S. iniae by intraperitoneal injection at a dosage of 8 × 106 CFU per fish. Results from the challenge also showed a significant difference between treatments and control (P = 0.0001). Overall, fish fed with strain SB3615 showed the lowest percent mortality (44.0 ± 7.2%) and those fed the control diet showed the highest mortality (77.3 ± 7.0%). The combined feeding with strains SB3086 and SB3615 did not result in any significant difference in reducing mortality because of S. iniae infection in juvenile Nile tilapia when compared with the individual probiotic treatments.  相似文献   

4.
Algamune? is a commercial additive produced from Euglena gracilis, providing a rich source of the β‐1,3‐glucan paramylon. Isolated kidney phagocytes of Nile tilapia were incubated with graded doses (0, 8, 16, 32, 64 and 128 μg/ml) of Algamune? and purified paramylon to gauge their ability to elicit the production of reactive oxygen species. A linear response was observed for extracellular superoxide anion for both sources but only Algamune? for intracellular superoxide anion. After corroborating the immunostimulant properties ex vivo, a feeding trial was conducted to evaluate the dietary supplementation of Algamune? (0, 100, 200, 400 and 800 mg/kg of diet) for Nile tilapia. Fish were fed for 3 weeks, after which, fish were sampled for blood and head kidney phagocytes. The remaining fish were challenged with Streptococcus iniae. Macrophage extracellular superoxide anion production was significantly elevated in fish fed diets with 200 mg of Algamune? kg?1 when compared to fish fed the basal diet. Even though the disease challenge did not show statistical differences, it is worth mentioning that fish fed intermediate doses of Algamune? had lowest numerical mortality values. Therefore, Algamune? was demonstrated to enhance some immunological responses of tilapia both in ex vivo and in vivo.  相似文献   

5.
The effect of dietary β‐glucan on the bacterial community in the gut of common carp (Cyprinus carpio) was examined after oral application of Aeromonas hydrophila. Carp received either feed supplemented with 1% MacroGard®, a β‐1,3/1,6‐glucan, or a β‐glucan‐free diet. Fourteen days after feeding, half of the carp from each group were intubated with 109 colony‐forming units (CFU) of a pathogenic strain of A. hydrophila. Gut samples were taken 12 hr to 7 days after application and analysed using microbiological and molecular biological techniques (NGS, RT‐PCR‐DGGE). The reaction of the mucosa and the microbiota to an A. hydrophila intubation differed in carp fed with β‐glucan compared to carp from the control group. In β‐glucan fed carp, the total bacterial amount was lower but the number of bacterial species was higher. Bacterial composition was different for carp from both treatment groups. The number of mucin filled goblet cells was reduced in carp fed the β‐glucan diet. Mucus was obviously released from the goblet cells and was probably washed out of the gut together with high numbers of bacteria. This might be protective against pathogenic bacteria and, therefore, feeding with β‐glucan may provide protection against infections of the gut in carp.  相似文献   

6.
Two experiments were conducted to examine the effect of commercially available beta‐glucan (Macrogard) and nucleotide (Aquagen) on the resistance to Streptococcus iniae infections in vaccinated or nonvaccinated juvenile red‐tail black sharks (Epalzeorhynchos bicolor, RTB) (1.4 ± 0.4 g weight total (WT), 5.6 ± 0.5 cm total length (TL)). The immunostimulants were added to a control diet formulated without any yeast source following the recommended doses of 1 g/kg feed for the beta‐glucan and 2 g/kg feed for the nucleotide. Beginning 4 d after introduction into tanks, fish were fed the experimental diets for 24 d, at 3% body weight per day, divided into two feedings. At the end of this period, fish were challenged by an intracoelomic injection of S. iniae. In the first experiment, both vaccinated and nonvaccinated fish were fed one of the two immunostimulants. In the second experiment, only vaccinated fish were fed the immunostimulants. Fish were vaccinated a week after being introduced into the system and challenged by intracoelomic injection with 1.5 × 105 S. iniae colony‐forming units /fish after three additional weeks; mortality was recorded for 2 wk after the bacterial challenge. In the first experiment, the mortality of both vaccinated and nonvaccinated fish fed beta‐glucan (23 ± 7% and 82 ± 1%, respectively) or nucleotide (28 ± 6% and 86 ± 5%, respectively) was significantly lower than the mortality of the control groups (35 ± 4% and 93 ± 5%, respectively), but there was no significant difference in mortality between fish fed beta‐glucan or nucleotide. In the second experiment, the mortality of vaccinated fish fed beta‐glucan (25 ± 7%) or nucleotide (43 ± 9%) was significantly lower than that of vaccinated fish fed the control diet (69 ± 7%). In both experiments, there was no significant difference in growth rate among fish fed immunostimulants or the control diet. The results of this investigation demonstrated the efficacy of beta‐glucans and nucleotides in increasing resistance to S. iniae in RTB sharks.  相似文献   

7.
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8.
A 4‐week growth trial was conducted to compare the effects of different feeding strategies of dietary immunostimulants on the growth, immunity and resistance against Vibrio splendidus of sea cucumbers Apostichopus japonicus (Selenka). Six feeding strategies were set, including feeding immunostimulants‐free diet continuously (control), feeding dietary β‐glucan (1.25 g kg?1 diet) continuously, feeding dietary mannan‐oligosaccharides (MOS; 2.00 g kg?1 diet) continuously, feeding β‐glucan 2 days followed by MOS 5 days alternately, feeding β‐glucan 5 days followed by MOS 2 days alternately and feeding β‐glucan 7 days followed by MOS 7 days alternately. The sea cucumbers fed immunostimulants showed higher specific growth rate (SGR) and lower cumulative mortality than control (P < 0.05). When sea cucumbers were fed with β‐glucan continuously, total coelomocytes counts and superoxide anion were significantly higher than control on the 4th day (P < 0.05). However, these two immune parameters were not significantly higher than those in control after the 18th day (P > 0.05). While sea cucumbers continuously fed MOS, these two immune parameters were not significantly higher than control until the 15th day. All immune parameters of the sea cucumbers fed with β‐glucan and MOS alternately were significantly higher than those in control during the experiment (P < 0.05). The sea cucumbers fed with β‐glucan 7 days followed MOS 7 days alternately showed the highest SGR and second lowest cumulative mortality. It was suggested that this feeding strategy is most suitable for sea cucumbers.  相似文献   

9.
The white shrimp Litopenaeus vannamei, fed immunostimulant‐free, 0.2%β‐glucan and 0.06% glycyrrhizin diets for 18 days, respectively, were challenged with Vibrio alginolyticus at 6.4 × 104 CFU shrimp?1. The total haemocyte count (THC), phenoloxidase (PO) activity, respiratory burst (RB) and superoxide dismutase (SOD) activity changes for a 120‐h period were investigated, and shrimp mortality was also recorded. The results showed that PO activity, RB and SOD activity were significantly higher in shrimp fed the two immunostimulant diets after 18 days than those in shrimp fed immunostimulant‐free diets. The THC and SOD activity decreased significantly from 0 to 24 h post challenge, and then reverted to normal levels at 96 and 72 h respectively. The values for PO activity and RB increased from 0 to 48 h post challenge. Compared with those fed the control diets, shrimp fed immunostimulants had significantly higher PO activity and RB values at 120 h post challenge. Mortalities after challenge with V. alginolyticus were significantly lower in shrimp fed with β‐glucan or glycyrrhizin than in those fed with a diet without immunostimulants. It was concluded that dietary β‐glucan and glycyrrhizin increased the shrimp immunity. Furthermore, β‐glucan caused an increase in some immune parameters 12 h earlier than glycyrrhizin after V. alginolyticus challenge.  相似文献   

10.
The effects of dietary β‐ (1,3) glucan and whole cell yeast (Sacharomyces uvarum) on the immune response and disease resistance to Aeromonas hydrophila were investigated in Cyprinus carpio. β‐(1,3) glucan was extracted from the yeast. Both β‐(1,3) glucan and whole yeast were incorporated into the diet at 1% level and fed to common carp C. carpio for a period of 60 days. Control and treated fish were exposed to A. hydrophila on the 30th and the 60th day of the experimental period. Dietary supplementation of glucan significantly increased the white blood cell count in fish on the 60th day (2.91±0.04 × 104), and the highest nuetrophil nitro blue tetrazolium (NBT) activity was also observed in glucan‐fed fish (30th day). A consistent increase in neutrophil (NBT) activity was also observed in whole cell fed fish until the end of the experiment. Similarly, β‐(1,3) glucan and whole cell yeast enhanced the serum lysozyme activity from the 15th day onwards but higher activity was reported on the 30th day in glucan and the 60th day in whole cell yeast‐fed fish. Suplementation of β‐(1,3) glucan protected the fish from A. hydrophila infection. Nearly 75–80% of the fish survived pathogen exposure (relative percentage survival). However, only 54–60% survival was observed in the whole cell‐fed fish. β‐(1,3) glucan and whole cell yeast protect the fish from pathogens by enhancing the cellular and humoral immune response in C. carpio.  相似文献   

11.
This study was conducted to evaluate the efficacy of β-glucan and selenium supplements to the diet on increasing survival of hybrid striped bass Morone chrysops X M. saxatilis exposed to Streptococcus iniae. A 2 × 2 × 2 factorial design was employed by including purified casein/gelatin-based diets and practical menhaden fish meal-based diets with supplement! of either β-glucan from barley at 0 and 0.1 % of diet or sodium selenite at 0 or 0.2 mg/kg diet or a combination of these supplements. All diets were formulated to meet the nutritional needs of hybrid striped bass with the exception of selenium. The purified and practical basal diets contained 0.03 and 1.03 mg Se/kg, respectively, and the diets supplemented with sodium selenite had an additional 0.07 mg Se/kg on average. Juvenile hybrid striped bass initially averaging 2.44 ± 0.17 g/fish were fed the eight experimental diets in triplicate 110-L recirculating aquaria for 6 wk, after which they were immersed in a bath of S. iniae at 6.2 × 106 CFU/mL for 2 h and monitored for 21 d. Weighi gain and feed efficiency were significantly (P < 0.05) affected by diet type and selenium supplementation, with fish fed practical diets and those supplemented with selenium having the greatest values. Supplementation of β-glucan to the purified or practical type diets did not significantly affect survival of fish after experimental infection. The most notable difference (P < 0.0001) was in the comparison of diet type; the survival rate of fish fed the practical diets was 75% compared to 35% for those fed the purified diets. Dietary supplementation of β-glucan did not enhance disease resistance in the present study. Fish fed menhaden fish meal-based diets were significantly more resistant to 5. iniae in comparison to the those fed the purified diets. Thus, nutritional influences on disease resistance of hybrid striped bass were evident in this study and warrant further investigation.  相似文献   

12.
The goal of this study was to investigate the effects of dietary supplementation with β‐glucan and microencapsulated probiotics (Bacillus subtilis or Pediococcus acidilactici) on growth performance, body composition, haemolymph constituents, and intestinal morphology and microbiota of the Pacific white shrimp Litopenaeus vannamei. Four treatment diets [basal diet (C), β‐glucan‐containing diet (β‐glu), β‐glucan plus B. subtilis‐containing diet (β‐glu+Bs), and β‐glucan plus P. acidilactici‐containing diet (β‐glu+Pa)] were fed to L. vannamei for 90 days. Shrimp fed the β‐glu and β‐glu+Pa diets exhibited similar growth performance and body protein content, which were significantly higher than those of shrimp fed the control diet (P < 0.05). No significant differences in haemolymph triglyceride, cholesterol, protein, haemolymph urea nitrogen or chloride were detected among the experimental diets. However, dietary β‐glucan alone increased the haemolymph glucose level and osmolarity (P < 0.05). Synbiotic supplementation had greater effects on intestinal microbiota and morphology than dietary β‐glucan alone. For example, β‐glu+Bs increased the number of intestinal lactic acid bacteria and decreased the number of Vibrio spp. (P < 0.05), and β‐glu+Pa increased the height of intestinal villi.  相似文献   

13.
This study determined the growth performance and acquired resistance of Nile tilapia, Oreochromis niloticus (L.) that survived Streptococcus iniae infection. Tilapia were challenged with three doses of S. iniae (8.8 × 103, 8.8 × 104 and 8.8 × 105 CFU fish?1 for low, medium and high challenges respectively). Groups of non‐injected and tryptic soy broth‐injected fish were maintained as controls. Significantly (P<0.05) higher mortality (45.0%) occurred in the high challenge treatment than in the low challenge treatment group (29.6%). The medium challenge group had mortality (36.3%) that did not differ significantly from the high or low treatment. Few fish died in the non‐injected and broth‐injected treatments (3.4% and 0.8% respectively). The tilapia that survived S. iniae infection used to assess growth performance were selected from survivors without gross clinical signs of disease. These fish were randomly stocked at a rate of 30 fish into each 57 L aquarium in triplicate and fed to apparent satiation for 8 weeks. No significant differences were detected in weight gain, feed intake, feed efficiency ratio or survival between S. iniae‐survived tilapia and the control treatments following the 8‐week growth performance trial. Following the 8‐week feeding study, tilapia were challenged with 1 × 106 CFU fish?1 of S. iniae to assess acquired immunity. Mean cumulative mortality was significantly higher (P<0.05) in the control treatments (41.7% for the non‐injected and 43.3% for the broth‐injected fish) than in the low, medium and high challenge treatments (7.4%, 3.3% and 8.3% respectively). Serum protein was significantly (P<0.05) elevated in the S. iniae‐survived tilapia that were subsequently challenged when compared with controls challenged for the first time. Agglutinating antibody titre was significantly higher in the fish in the medium and high challenge treatments, compared with the control fish challenged for the first time. The results suggest tilapia that survive S. iniae challenge without showing overt disease signs performed as well as non‐infected tilapia. Further, the S. iniae‐survived tilapia challenged following the 8‐week growth performance trial gained acquired resistance to homologous S. iniae challenge.  相似文献   

14.
β‐Glucooligosaccharides (BGO), produced from barley β‐glucan, were used as a feed supplement (0.1%) for juvenile olive flounder (Paralichthys olivaceus) to identify and quantify its oral administration effects on innate immunomodulation and infectious disease protection. Juvenile flounders (14 ± 0.5 g) were divided into two groups fed either 0.1% BGO (treatment) or a standard diet (control) for 8 weeks. At the end of the experiment, investigation of the effects was carried out through systemic studies on growth performance, serum and mucus biochemical parameters, innate immunity, microvillus length, and relative pro‐inflammatory cytokine gene expression. The results demonstrated that the BGO diet produced slightly higher levels of growth performance, serum protein, microvillus length and pro‐inflammatory cytokine gene (tumour necrosis factor‐α, interleukin [IL]‐1β, and IL‐6) expression without any significant differences (p > .05). All innate immunity parameters were up‐regulated by BGO administration and, among these, respiratory burst, lysozyme and superoxide dismutase (SOD) were significantly different (p < .05). Fish in the both groups were challenged with Streptococcus iniae (1.35 × 108 CFU/ml), and BGO group was focused to confirm the promotion of innate immunity parameters. The results showed a significantly (p < .05) lower death rate compared with that of the control. Therefore, BGO could be used as a new prebiotic in future olive flounder aquaculture as well as to control streptococcosis.  相似文献   

15.
The effects of dietary linoleic (LA) and linolenic acids (LN) on growth and immunity of all‐male hybrid tilapia, Oreochromis niloticus × Oreochromis aureus, were evaluated for 10 wk. Fish fed 0.12% LA + 0% LN had the lowest weight gain (WG) but was not significantly different from diets containing 0.5% LA or 0.40% LA + 1.0% LN. Fish fed 1% LA had the highest WG but did not differ from diets with 0.5% LA, 2.0% LA, 0.26% LA + 0.5% LN, 0.69% LA + 2.0% LN, or diets containing both LA and LN at 0.25, 0.5, and 1.0%. Feed intake, feed efficiency, and survival did not differ among treatments. Total body n‐6 fatty acids (FAs) increased with increasing dietary levels of n‐6. Total body n‐3 FAs also appeared to increase with increasing dietary n‐3 levels but peaked at 1% of diet. Dietary treatment had no effect on hematology, immune function, or survival to Streptococcus iniae. This study indicates that both LA and LN are dietary essential for growth of hybrid tilapia. Dietary LA alone can meet the essential FA requirement, and a level of 1.14% of diet is required for optimum growth.  相似文献   

16.
A feeding experiment was conducted to determine the dietary calcium (Ca) requirement for juvenile hybrid tilapia, Oreochromis niloticus × O. aureus reared in nature water. Purified diet supplemented with 0, 1, 2, 3, 4, 5, 7 and 10 g Ca kg−1 diet providing of 0.6, 1.6, 2.6, 3.7, 4.7, 5.5, 7.5 and 10.7 g Ca kg−1 diet, respectively, were fed to tilapia (mean initial weight: 0.52 ± 0.01 g, n = 3) for 8 weeks. Each diet was fed to three replicate groups of fish in a closed, recirculating fresh water rearing system. The rearing water contained 27.1–33.3 mg L−1 Ca. The tilapia fed the diets supplemented with ≥3.7 g Ca kg−1 had significantly (P < 0.05) higher weight gain, when compared with fish fed the diet with ≤1.6 g Ca kg−1. Fish fed the unsupplemented control showed significantly lower weight gain when compared with the other groups (P < 0.05). Bone Ca concentration was highest in fish fed the diets with ≥4.7 g Ca kg−1, intermediate in fish fed the diet with 2.6 g Ca kg−1 and lowest in fish fed the control diet. Scale Ca concentration was higher in fish fed the diets with ≥3.7 g Ca kg−1 than in fish fed the diets with ≤2.6 g Ca kg−1. Serum alkaline phosphatase activity was 36% increased in fish fed the diets with ≥2.6 g Ca kg−1 than fish fed the diets with <1.6 g Ca kg−1. Analysis by broken‐line regression of weight gain, bone and scale Ca concentrations indicated that the adequate dietary Ca concentration for tilapia in water containing 27.1–33.3 mg Ca L−1 was 3.5, 4.3 and 4.2 g Ca kg−1 diet, respectively, supplied as Ca‐lactate.  相似文献   

17.
Dietary supplementation of yeast or yeast subcomponents (YYS) as commercial preparations of β‐glucan (MacroGard®; Biotec‐Mackzymal, Tromsø, Norway; and Betagard A®; Aqua‐In‐Tech, Inc., Seattle, WA, USA), mannan oligosaccharide (Bio‐Mos? Aqua Grade; Alltech, Nicholasville, KY, USA), or whole‐cell Saccharomyces cerevisiae (Levucell SB20®; Lallemand Animal Nutrition, Milwaukee, WI, USA) at the manufacturer’s recommended levels was evaluated on the physiological performance of juvenile channel catfish, Ictalurus punctatus. Fish were fed YYS diets for 4 wk, followed by 2 wk of control diet. Fish were sampled at the end of each feeding period (4 and 6 wk) to measure hematological and immune parameters and growth and to determine the effects of dietary β‐glucan on resistance to Edwardsiella ictaluri infection and to low‐water stress (6 wk). Supplementation of YYS in diets did not affect growth performance, hematology, or immune function. Survival from E. ictaluri infection was from 5 to 17.5% higher in fish fed YYS diets than in the control group, but the increases were not significant. Some improvement in stress resistance was observed in YYS‐fed catfish after exposure to low‐water stress. Stress reduction in fish fed diets supplemented with yeast subcomponents has been reported previously, but thus far, no explanation has been proposed for this effect. The present study and the previously published research suggest that dietary YYS supplementation does not appear to improve resistance of channel catfish to E. ictaluri.  相似文献   

18.
A feeding trial was conducted in aquaria with juvenile hybrid tilapia (Oreochromis niloticus×Oreochromis aureus) to evaluate the use of different protein sources in combination with distillers dried grains with solubles (DDGS). Twelve 110‐L glass aquaria were stocked with 28 juvenile (2.7±0.5‐g) hybrid tilapia per aquarium. Three replicate aquaria were randomly assigned to each of the four dietary treatments. Diets were isonitrogenous and isocaloric. The control diet contained 12% fish meal and 41% soybean meal as the primary protein sources (Diet 1). Each experimental diet contained 30% DDGS by weight, in combination with 8% fish meal and 34% soybean meal (Diet 2), 26% meat and bone meal (MBM), and 16% soybean meal (Diet 3), or 46% soybean meal alone (Diet 4). Fish were fed to apparent satiation twice a day for 10 weeks. There were no significant differences (P>0.05) in average weight gain, specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) among tilapia fed Diets 1, 2, and 3. Fish fed Diet 4 had significantly lower (P<0.05) average weight gain, SGR, and PER than fish fed Diets 1 and 3. Relative cost per unit weight gain for Diets 1, 2, and 3 were statistically similar (P>0.05), while cost per unit weight gain for Diet 4 was significantly higher (P<0.05) than other diets. Diet 3 represented approximately a 20% cost savings compared with the control diet, with no reduction in growth. This study indicates that diets without fish meal containing 30% DDGS in combination with MBM and soybean meal provide good growth in tilapia. A diet without animal protein did not support acceptable growth.  相似文献   

19.
This study was conducted to evaluate the effect of dietary levels of distiller’s dried grains with solubles (DDGS) on growth, body composition, hematology, and resistance of Nile tilapia, Oreochromis niloticus, to Streptococcus iniae challenge. Five isocaloric diets containing DDGS at levels of 0, 10, 20, and 40%, and 40% DDGS + lysine (Diets 1–5) as partial replacements of a combination of soybean meal (SBM) and corn meal (CM) on an equal protein basis were fed to juvenile Nile tilapia (9.41 ± 0.14 g) for 10 wk. Fish fed Diet 4 had the lowest weight gain (WG), feed efficiency ratio, protein efficiency ratio (PER), and whole‐body protein. Supplementation of lysine to the 40% DDGS diet (Diet 5) improved WG and PER. Hematological and immunological parameters were not affected by dietary treatment. There were no significant differences among the average number of days to first mortality after S. iniae challenge and cumulative mortality 14 d postchallenge among fish in various treatments. DDGS can be incorporated in tilapia diet at a level of 20% as a substitute for a combination of SBM and CM without affecting their growth performance, body composition, hematological parameters, immune response, and resistance to S. iniae infection.  相似文献   

20.
An 8‐week feeding trial was conducted to investigate the effect of supplemental dietary zinc sources on the growth performance and carbohydrate utilization of juvenile tilapia Smith 1840, Oreochromis niloticus × O. aureus. The goal was to compare the bioavailability of two zinc sources, zinc sulphate (ZnSO4) or zinc methionine (ZnMet), by using two practical basal diets with 350 g kg?1 (C350) or 400 g kg?1 (C400) carbohydrates based on wheat as the carbohydrate source. The results showed that fish fed with a diet supplemented with 60 mg kg?1 Zn from either ZnSO4 or ZnMet had a significantly (P < 0.05) greater specific growth rate and protein efficiency ratio than those fed with the diets of ≤30 mg kg?1 Zn. The composition of tilapia carcass was also found to be influenced by various levels of dietary zinc from the two zinc sources. The G6P‐DH in fish fed with the 20 mg kg?1 ZnMet diet and the PK levels in fish fed with 20 mg kg?1 ZnSO4 and 30 mg kg?1 ZnMet diet were significantly (P < 0.05) higher than those in fish fed with the C400 diet. The data suggest that supplemental dietary zinc from either ZnMet or ZnSO4 significantly affects the growth performance and carbohydrate utilization of tilapia.  相似文献   

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