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This study aimed to assess the viability of replacing rice bran with spent coffee grounds (SCG) in the diets of Oreochromis niloticus (average body weight, 48.8 ± 0.42 g). The fish were randomly allocated into four sets of three groups each and placed in net cages (1 m × 2 m × 0.5 m) at a density of 30 fish per cage. They were fed diets with four different replacement levels: 0%, 5%, 10%, and 15% of SCG over a period of 90 days. Growth and serum biochemical indices were monitored three times at 30, 60, and 90 days. During the experiment, there were no significant differences (P > 0.05) observed in growth indices, including weight gain (WG), daily WG, specific growth rate, feed conversion rate, protein efficiency ratio, and survival rate among the groups at 30, 60, and 90 days. Serum biochemical indices, such as aspartate aminotransferase and alanine aminotransferase, showed a similar trend with significant differences observed only on day 30, while the lowest and highest levels were found in the control and 15% SCG replacement groups, respectively. For total cholesterol, a significantly different result was found only on day 30. However, these differences were not sustained in subsequent assessments. Conversely, serum glucose, total protein, albumin, and globulin remained unaffected by SCG replacement throughout the experiment. The findings indicate that replacing rice bran with up to 15% SCG did not adversely impact the growth performance or key serum biochemical indices of Nile tilapia. To the researchers' knowledge, these findings are the first in the field to substitute SCG for rice bran, opening a new avenue for further research. [ABSTRACT FROM AUTHOR]

Yellow mealworm (Tenebrio molitor) meal was introduced to aquafeed as a suitable protein source to replace fish meal (FM) and soybean meal and, thereby, consistent aquaculture production. However, mealworms should be added at adequate levels due to the presence of antinutritional factors such as chitin. Consequently, sodium butyrate (SB) is suggested to improve feed quality and ensure aquatic animals' productivity and welfare. In this study, parallel with the protein source (T. molitor meal or FM), dietary supplementation of SB (1 g/kg) is involved as a factor in the 2 × 2 factorial study. The first and the second diets were formulated using FM as a protein source with or without SB, while the third and fourth diets were prepared by replacing FM with T. molitor meal with or without SB supplementation. After 60 days, fish fed with FM or T. molitor and SB showed improved final body weight and weight gain, while those fed with T. molitor without SB had a reduced protein efficiency ratio. Histological analysis revealed that dietary SB improved intestinal histological features by increasing the height and branching of intestinal villi and immune cell infiltration near intestinal crypts in Nile tilapia-fed FM or T. molitor. Furthermore, fish-fed FM or T. molitor and SB had higher Hb, red blood cells, PCV, total protein, and globulin levels than fish-fed respective test diets without SB supplementation. Dietary SB addition to FM or T. molitor-based diets also significantly enhanced blood lysozyme and phagocytic activities, catalase, superoxide dismutase, glutathione peroxidase, and reduced MDA levels. Our results demonstrate that T. molitor meal can replace FM without compromising Nile tilapia's growth performance and health status. Additionally, SB supplementation improved T. molitor meal utilization by Nile tilapia, thereby significantly enhancing the growth, digestion capacity, intestinal histological features, and antioxidative and immune responses. Consequently, dietary T. molitor meal reduces the reliance on FM and improves the sustainability and efficiency of Nile tilapia production. [ABSTRACT FROM AUTHOR]

To exploit aquatic animals' feed resources and functional ingredients and additives, this experiment investigated the effects (a 2 × 2 factorial trial) and mechanism of woody plants and probiotics on Nile tilapia. Each treatment group was randomly assigned triplicate nets of 40 fish (initial body weight of 35.04 ± 0.01 g) in 12 tanks for 56 days. Fish were fed four diets, including a CON–CON diet (with no supplementation) and CON–Ba (basal diet + 1 × 107 CFU/g B. amyloliquefaciens), MO-CON (basal diet + 10% Moringa oleifera) and MO-Ba (basal diet + 1 × 107 CFU/g B. amyloliquefaciens + 10% Moringa oleifera) until apparent satiation (2 meals/day). The results showed that the MO diet had a lower feed conversion ratio than the non-MO diets (P < 0.05). The weight gain in the Ba group was significantly higher than those in the groups without Ba treatment (P < 0.05). Both MO and Ba improved the morphological indices when applied individually (P < 0.05). Ba supplementation improved the activities of digestive enzymes (P < 0.05). MO significantly upregulated the gene expression of TNF-α, IL-6, IL-10, and C3 in the spleen of Nile tilapia (P < 0.05), while Ba significantly upregulated the gene expression of IL-6 and C3 (P < 0.05). The microbiological analyses showed that the abundances of beneficial bacteria increased, and the relative abundances of pathogenic bacteria decreased in fish-fed MO. In conclusion, dietary MO and Ba can effectively improve the immunity of Nile tilapia, while Ba can enhance the activities of digestive enzymes. The synergistic effect of MO and Ba on the intestinal microbiota of Nile tilapia promotes growth, thus showing promising application prospects. [ABSTRACT FROM AUTHOR]

Nile tilapia, Oreochromis niloticus, (2.00 ± 0.02 g) were reared in 16 70-L tanks (40 individual/tank) and fed diets (approx. 345 g/kg protein, approx. 87 g/kg crude fat) containing 0 (CTL), 75 (PH-75), 150 (PH-150), and 300 (PH-300) mg/kg phytol (n = 4). After 60 days of feeding (4% daily), growth performance, humoral immune parameters, and gut bacteria were analyzed. Also, hepatic antioxidant parameters were determined before and after the fish were transported in plastic bags for 6 hr. The results showed that PH-75 exhibited the highest final weight (P < 0.001), weight gain (P < 0.001), feed intake (P < 0.001), feed efficiency (P = 0.015), plasma lysozyme activity (P = 0.004), and intestinal Lactobacillus sp. population (P = 0.017), among the treatments. The highest plasma alternative complement activity (P = 0.006) and the lowest intestinal total viable bacteria (P = 0.027) were observed in PH-75 and PH-150. The highest plasma alkaline phosphatase activities were observed in PH-75 and PH-300 (P = 0.014). The highest blood leukocyte (P = 0.008), monocyte (P = 0.010), and eosinophil (P < 0.001) were observed in PH-300, while the highest blood neutrophil was observed in all phytol treatments (P < 0.001). The highest hepatic lipid peroxidation was observed in PH-300, whereas PH-75 and PH-150 showed the lowest values (P < 0.001). The highest hepatic reduced glutathione was observed in PH-75, also PH-150 exhibited significant elevation in this parameter, compared to CTL (P < 0.001). Transportation led to significant elevations in the hepatic antioxidant enzymes' activities in CTL, PH-75, and PH-150; the highest activities were related to PH-75 and PH-150 treatments, which had also the highest post-transportation survivals (P < 0.001). In conclusion, phytol is a suitable feed supplement for Nile tilapia, improving growth performance and welfare, particularly at 75 mg/kg. [ABSTRACT FROM AUTHOR]

Alkalinity stress is the main stress experienced by aquatic animals in saline–alkali water, which hinders the aquaculture development and the utilization of water resources. The two-factor (2 × 3) test was adopted to study the influence of dietary protein to carbohydrate ratios on the energy metabolism of Nile tilapia (Oreochromis niloticus) under different alkalinity stress levels. Three diets with different protein-carbohydrate ratios (P27/C35, P35/C25, and P42/C15) were fed to fish cultured in freshwater (FW, 1.3 mmol/L carbonate alkalinity) or alkaline water (AW, 35.7 mmol/L carbonate alkalinity) for 50 days. Ambient alkalinity decreased tilapia growth performance. Although ambient alkalinity caused oxidative stress and enhanced ion transport and ammonia metabolism in tilapia, tilapia fed the P27/C35 diet showed better adaptability than fish fed the other two diets in alkaline water. Further metabolomic analysis showed that tilapia upregulated all the pathways enriched in this study to cope with alkalinity stress. Under alkalinity stress, tilapia fed the P27/C35 diet exhibited enhanced pyruvate metabolism and purine metabolism compared with tilapia fed the P42/C15 diet. This study indicated that ambient alkalinity could significantly decrease growth performance and cause oxidative stress and osmotic regulation. However, reducing dietary protein content by increasing carbohydrates could weaken stress and improve growth performance, ion transport, and ammonia metabolism in tilapia under long-term hyperalkaline exposure. [ABSTRACT FROM AUTHOR]

Insects are potential alternative protein sources to replace fish meal (FM) in aqua feed. The role of insect species as replacements in the aqua industry has been a hot debate in the current era. The present study evaluated the influence of FM replacement with insect-based meals (black soldier fly (BSF) and maggot fly) in the feed of Nile tilapia. Eight diets with graded replacement levels of FM were formulated along with basal diet as T0 (control group having basal diet), T1 (25% maggot meal (MM) with 2% probiotics), T2 (50% MM + 2% probiotics), T3 (75% MM + 2% probiotics), T4 (100% MM + 2% probiotics), T5 (25% BSF meal (BSFM) + 2% probiotics), T6 (50% BSFM + 2% probiotics), T7 (75% BSFM + 2% probiotics), and T8 (100% BSFM + 2% probiotics). Fish having an initial body weight of 7 g were fed on formulated feed for 16 weeks. Growth parameters, including weight, length, feed conversion ratio, specific growth rate, and survival rate, were observed weekly, and significant (p < 0.05) results were attained up to 75% replacement level with no adverse effect on growth. However, at 100% replacement of FM, fish growth was retarded. Maximum survival rate was observed in T1 and T5 and minimal in T4 and T8. Body composition, including crude protein, fat, moisture, and ash, showed significant (p < 0.05) results. Similarly, digestive enzyme (protease, lipase, and amylase) activity was measured at the end of the trial. Fish in T1 and T5 groups had the highest digestive enzyme activity, which slightly decreased with the inclusion of insect-based meals and probiotics. Statistically significant (p < 0.05) results were observed for antioxidant enzyme activity in catalase, glutathione peroxidase, and superoxide dismutase. The most vigorous immune response was shown in T1 and T5, with higher white blood cells and high levels of IgM. The present research showed that FM could be replaced with BSF meal and MM with probiotics up to 50% for better fish health performance; however, 75% replaced FM without compromising growth and health status. [ABSTRACT FROM AUTHOR]

Natural immune stimulants are among the most effective chemicals for boosting immunity and fish welfare. This study aims to investigate the effects of red macroalgae extract (Laurencia caspica) on hematological, immunological, antioxidant, biochemical, and disease resistance against S. agalactiae in Nile tilapia for 50 days. For this purpose, fishes were assigned to four dietary treatments group in which the base meal was supplemented with 0.5%, 1%, and 2% of L. caspica extract. On days 25 and 50 of the experiment, samples were taken to investigate the hematological, immunological, biochemical, and antioxidant parameters. The white blood cells (WBCs), hemoglobin, and neutrophils significantly increased after 50 days of feeding with the L. caspica extract, but until the 25th day, no significant difference was observed among the treatments except for hemoglobin. Immunological parameters (including Immunoglobulin M [IgM] and complement 3 [C3]) were significantly higher in treated groups compared to control both 25 days and 50 days posttreatment. However, on the 25th day, no significant difference was noticed between treatments and control in the case of lysozyme activity. Alkaline phosphatase (ALP) and alanine aminotransferase (ALT) considerably increased in comparison to the control group on the 50th day, but no significant difference was observed on the 25th day. In addition, feeding with L. caspica significantly increased the antioxidant enzyme activities on the 25th day (L. caspica 1% and 2% in peroxidase [POD] and superoxide dismutase [SOD] in all groups) and 50th day (catalase [CAT], SOD and L. caspica 1% and 2% in POD) in the spleen. The survival rate of fish challenged with Streptococcus agalactiae was considerably greater than the control group. Finally, it can be concluded that L. caspica extract is an immunological stimulant that induces fish resistance to S. agalactiae. [ABSTRACT FROM AUTHOR]

This study investigated the effects of the oat bran addition on the growth performance and intestinal health of Nile tilapia (Oreochromis niloticus) exposed to copper ions. Four groups of diets containing 0%, 5%, 10%, and 20% oat bran were fed to Nile tilapia for four weeks. The results showed that oat bran had a dose-dependent effect on the growth performance of Nile tilapia. The addition of oat bran can increase the relative abundance of Delftia, which is capable of degrading heavy metals in the intestinal tract and alleviating the intestinal damage caused by copper ion stress. Compared to the control group, the 5% oat bran group had an increased intestinal antioxidant capacity. The relative gene expression of proinflammatory factors (NF-κB, IL-1β) was significantly downregulated in the 5% oat bran group (P < 0.05), and the relative gene expression of anti-inflammatory factors (TGF-β), HIF-1α, occludin, and claudin was significantly upregulated (P < 0.05). In conclusion, we suggest that 5% oat bran should be added to the diet to improve the growth performance of Nile tilapia and alleviate the negative effects of copper ion stress on intestinal health. [ABSTRACT FROM AUTHOR]

Despite the usage of nanoparticles (NPs) is rapidly increasing, several experts have noted the risk of their release into ecosystems and their potential negative impacts on biological systems. However, the available studies on the neurobehavioral impacts of aluminum oxide nanoparticles (Al2O3NPs) on aquatic organisms are little. Hence, this study targeted to ascertain the harmful effects of Al2O3NPs on behavioral characteristics and genotoxic and oxidative damages in Nile tilapia fish. In addition, the beneficial role of chamomile essential oil (CEO) supplementation in reducing these effects was also investigated. In the current study, fish were distributed into 4 equal groups (n = 60 fish per group). The control group was fed a plain diet only, the CEO group received a basic diet complemented with CEO at a level of 2 mg/kg diet, the ALNP group received a basic diet and was exposed to an approximate concentration of 1/10th LC50 of ALNPs nearly 5.08 mg/L, and the combination group (ALNPs/CEO group) received a basal diet coadministered with ALNPs and CEO at the aforementioned percentages. The findings revealed that O. niloticus exhibit neurobehavioral changes along with changes in the level of GABA, monoamines in the brain tissue, and serum amino acid neurotransmitters, besides a reduction of AChE and Na+/K+-ATPase activities. In addition to brain tissue oxidative damage with upregulation of proinflammatory and stress genes, such as HSP70 and caspase-3, supplementation of CEO significantly reduced the negative impacts of ALNPs. These results showed that CEO has neuroprotective, antioxidant, genoprotective, anti-inflammatory, and antiapoptotic properties in fish that have been exposed to ALNPs. Therefore, we advise its usage as a valuable addition to fish diet. [ABSTRACT FROM AUTHOR]

Ammonia is a key risk factor in intensive aquaculture systems. This experiment is aimed at investigating the influence of dietary protein levels on genetically improved farmed tilapia (GIFT, Oreochromis niloticus) under chronic ammonia stress. GIFT juveniles of 4.00 ± 0.55 g were exposed to high ammonia level at 0.88 mg/L and fed with six diets comprising graded protein levels at 22.64%, 27.26%, 31.04%, 35.63%, 38.47%, and 42.66% for 8 weeks. The fish in negative control was fed the diet with 31.04% protein in normal water (0.02 mg ammonia/L water). Our results showed that high ammonia exposure (0.88 mg/L) caused significant decrease in fish growth performance, hematological parameters, liver antioxidant enzymes (catalase and glutathione peroxidase), and gill Na+- and K+-dependent adenosine triphosphatase (Na+/K+-ATP) activity. When fish were under high ammonia exposure, the weight gain rate, special growth rate, feed efficiency, and survival rate elevated significantly with dietary protein supplementation increase to 35.63%, whereas protein efficiency ratio, hepatosomatic index, and viscerosomatic index showed a decreased tendency. Dietary protein administration significantly enhanced crude protein but reduced crude lipid contents in the whole fish. Fish fed diets with 35.63%-42.66% protein had higher red blood cell counts and hematocrit percentage than fish fed 22.64% protein diet. The values of serum biochemical indices (lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase), hepatic antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase), and gill Na+/K+-ATP activity were all elevated with the increment of dietary protein. Moreover, histological analysis indicated that dietary protein administration could prevent the ammonia-induced damages in fish gill, kidney, and liver tissues. Based on weight gain rate as a response criterion, the optimal dietary protein requirement for GIFT juveniles under chronic ammonia stress was 37.9%. [ABSTRACT FROM AUTHOR]

Azolla is a potential fish feed ingredient due to its high nutritional value, abundant production, and low price. This study is aimed at evaluating the use of fresh green azolla (FGA) as a replacement ratio of the daily feed intake on the growth, digestive enzymes, hematobiochemical indices, antioxidant response, intestinal histology, body composition, and flesh quality of monosex Nile tilapia, Oreochromis niloticus (with an average initial weight of 108.0 ± 5.0 g). Five experimental groups were used and differed in commercial feed replacement rates of 0% ( T 0 ), 10% ( T 1 ), 20% ( T 2 ), 30% ( T 3 ), and 40% ( T 4 ) with FGA for 70 days. Results showed that 20% replacement with azolla gave the highest values of growth performance and hematological parameters and the best feed conversion ratio, protein efficiency ratio, and fish whole body protein content. The highest levels of intestinal chymotrypsin, trypsin, lipase, and amylase were noted in 20% replacement with azolla. Fish fed diets with FGA levels of 10% and 40% showed the highest values for the thickness of the mucosa and submucosa layers among all treatments, respectively, while the length and width of the villi decreased significantly. No significant (P > 0.05) differences in the activities of serum alanine transaminase, aspartate transaminase, and creatinine were detected among treatments. The hepatic total antioxidant capacity and the activities of catalase and superoxide dismutase significantly (P < 0.05) increased while the activity of malonaldehyde decreased with increasing the replacement levels of FGA up to 20%. With increasing levels of dietary replacement with FGA, muscular pH, stored loss (%), and frozen leakage rate (%) were significantly decreased. Finally, it was concluded that the dietary replacement of 20% FGA or less may be considered a promising feeding protocol for monosex Nile tilapia, which may lead to high fish growth, quality, profitability, and sustainability for the tilapia production sector. [ABSTRACT FROM AUTHOR]

Since high-fat diet (HFD) intake elevates liver cholesterol and enhanced cholesterol-bile acid flux alleviates its lipid deposition, we assumed that the promoted cholesterol-bile acid flux is an adaptive metabolism in fish when fed an HFD. The present study investigated the characteristic of cholesterol and fatty acid metabolism in Nile tilapia (Oreochromis niloticus) after feeding an HFD (13% lipid level) for four and eight weeks. Visually healthy Nile tilapia fingerlings (average weight 3.50 ± 0.05 g) were randomly distributed into four treatments (4-week control diet or HFD and 8-week control diet or HFD). The liver lipid deposition and health statue, cholesterol/bile acid, and fatty acid metabolism were analyzed in fish after short-term and long-term HFD intake. The results showed that 4-week HFD feeding did not change serum alanine transaminase (ALT) and aspartate transferase (AST) enzyme activities, along with comparable liver malondialdehyde (MDA) content. But higher serum ALT and AST enzyme activities and liver MDA content were observed in fish fed 8-week HFD. Intriguingly, remarkably accumulated total cholesterol (mainly cholesterol ester, CE) was observed in the liver of fish fed 4-week HFD, along with slightly elevated free fatty acids (FFAs) and comparable TG contents. Further molecular analysis in the liver showed that obvious accumulation of CE and total bile acids (TBAs) in fish fed 4-week HFD was mainly attributed to the enhancement of cholesterol synthesis, esterification, and bile acid synthesis. Furthermore, the increased protein expressions of acyl-CoA oxidase 1/2 (Acox1 and Acox2), which serve as peroxisomal fatty acid β-oxidation (FAO) rate-limiting enzymes and play key roles in the transformation of cholesterol into bile acids, were found in fish after 4-week HFD intake. Notably, 8-week HFD intake remarkably elevated FFA content (about 1.7-fold increase), and unaltered TBAs were found in fish liver, accompanied by suppressed Acox2 protein level and cholesterol/bile acid synthesis. Therefore, the robust cholesterol-bile acid flux serves as an adaptive metabolism in Nile tilapia when fed a short-term HFD and is possibly via stimulating peroxisomal FAO. This finding enlightens our understanding on the adaptive characteristics of cholesterol metabolism in fish fed an HFD and provides a new possible treatment strategy against metabolic disease induced by HFD in aquatic animals. [ABSTRACT FROM AUTHOR]

This study is aimed at assessing the feeding frequency for tilapia fingerlings. 240 fishes were randomly distributed in 24 containers. The feeding consisted of six frequencies: 4 (F4), 5 (F5), 6 (F6), 7 (F7), 8 (F8), and 9 (F9) times a day. The weight gain was significantly higher in F5 and F6 when compared to F4 (p = 0.0409 and 0.0306, respectively). Feed intake and apparent feed conversion did not differ between treatments (p = 0.129 and p = 0.451). About water quality, the nitrogen levels in the water from the treatments differed between F4 and F5 (p = 0.0478) and F4 and F6 (p = 0.0283) and for P between F4 and F6 (p = 0.0215) and F4 and F9 (p = 0.0432). The x 2 test showed a dependence relationship between feed frequencies and the muscle fibers frequency (p < 22 × 10 − 17 ), prevailing fibers between 10-20 micrometers in F4, F5, F6, and F7 and 30-40 in F8 and F9. The area of the hepatocytes differed only between F5 and F9, while the nucleus area did not. Partial net revenue differed in 10% between F5 and F4 (p = 0.0812) and between F6 and F4 (p = 0.0568). In conclusion, fingerlings fed 5 to 6 times a day have better zootechnical and partial recipes. [ABSTRACT FROM AUTHOR]

Finfish aquaculture is expected to continue to benefit from significantly improved fish diets, which are the source of energy to support the growth and health of fish. Strategies to enhance the transformation rate of dietary energy and protein to fish growth are greatly desired by fish culturists. Prebiotic compounds can be used as supplements to human, animal, and fish diets to populate beneficial bacteria in the gut. The goal of the present study is to identify low-cost prebiotic compounds with high efficacy in increasing the absorption of food nutrients by fish. Several oligosaccharides were evaluated as prebiotics in Nile tilapia (Oreochromis niloticus), one of the most widely cultured species in the world. Several parameters of the fish on different diets were evaluated, including feed conversion ratios (FCRs), enzymatic activities, expression of growth-related genes, and the gut microbiome. Two age groups of fish (30 days old and 90 days old) were used in this study. The results indicated that the addition of xylooligosaccharide (XOS), galactooligosaccharide (GOS), or XOS and GOS combination to the basic fish diet significantly decreased the feed conversion ratio (FCR) of the fish in both age groups. Both XOS and GOS decreased the FCR of 30-day-old fish by 34.4% compared to the fish on the control diet. In the 90-day-old fish group, XOS and GOS decreased the FCR by 11.9%, while the combination of the two prebiotics led to a 20.2% decrease in FCR compared to the control group. The application of XOS and GOS also elevated the production of glutathione-related enzymes and the enzymatic activity of glutathione peroxidase (GPX), indicating the enhancement of antioxidation processes in fish. These improvements were associated with significant changes in the fish gut microbiota. The abundance of Clostridium ruminantium, Brevinema andersonii, Shewanella amazonensis, Reyranella massiliensis, and Chitinilyticum aquatile were upregulated by XOS and GOS supplements. The findings of the present study suggested that the prebiotics would be more effective when they were applied to the younger fish, and the application of multiple oligosaccharide prebiotic compounds could result in a greater growth enhancement. The identified bacteria can be potentially used as probiotic supplements in the future to improve fish growth and feeding efficiency and ultimately reduce the cost of tilapia aquaculture. [ABSTRACT FROM AUTHOR]

A 60-day feeding experiment was performed to evaluate the effect of dietary astaxanthin on gonad development, the antioxidant system, and its inherent mechanism in female Nile tilapia (Oreochromis niloticus). Fish were fed with diets containing astaxanthin at five levels [0 mg/kg (control), 50 mg/kg, 100 mg/kg, 150 mg/kg, and 200 mg/kg]. At the end of experiment, the group fed with 150 mg/kg astaxanthin showed significantly increased specific growth rate, feed utilization, viscerosomatic index, and hepatosomatic index compared with the control group (P < 0.05). Gonad development was stimulated in the groups fed with 100 mg/kg and 150 mg/kg astaxanthin, and their gonadosomatic index and egg diameter were significantly higher than those of the control group and the group fed with 200 mg/kg astaxanthin. The ovaries of females in the groups fed with 100 mg/kg and 150 mg/kg astaxanthin were fully developed, the eggs were gray-yellow and uniform in size, and a large number of oocytes developed to stages IV and V. The serum levels of 17 β-estradiol, follicle-stimulating hormone, and luteinizing hormone were significantly higher in the groups fed with 100 mg/kg and 150 mg/kg astaxanthin than in the group fed with 200 mg/kg astaxanthin. Compared with the control and the other groups, the group fed with 150 mg/kg astaxanthin showed significantly higher transcript levels of genes encoding hormone receptors and higher catalase activity in ovarian tissues, lower malondialdehyde content, decreased apoptosis (reduced granulosa cell apoptosis and lower transcript levels of bax and caspase-3), and reduced follicular atresia. Gene ontology analyses revealed that cell division and the cell cycle were enriched with differentially expressed genes in the group fed with 150 mg/kg astaxanthin, compared with the control group. We concluded that dietary astaxanthin at a concentration of 150 mg/kg activates follicle development by inhibiting expression of mapk1 (involved in MAPK signaling) and increasing the expression genes involved in oocyte meiosis (chp2, ppp3ca, map2k1, and smc1a1) and progesterone-mediated oocyte maturation (igf1, plk1, and cdk1). In conclusion, female Nile tilapia fed with 150 mg/kg astaxanthin showed increased growth, reduced oxidative stress in ovarian tissue, lower levels of cell apoptosis, and improved oocyte development. [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of zinc threonine supplementation on growth, immunity-related genes, antioxidative stress, and resistance to heat stress (HS) in Nile tilapia. A total of 300 Nile tilapia (76.69 ± 0.11 g) were randomly allocated into five zinc treatments, with three replicates of 20 fish in each treatment. Based on the control group with zinc-free feeds, dietary zinc levels of 20 or 40 mg/kg diet were added in the form of zinc sulfate (ZnSO4) and zinc threonine (Thr-Zn). After 45 days of feeding, part of the fish was exposed to HS. The highest performance of growth and feed intake was found in fish fed with zinc (ZnSO4 or Thr-Zn) at 40 mg/kg, which also significantly elevated the villus length and absorption area. Additionally, significantly higher values of superoxide dismutase, catalase, and glutathione peroxidase activity but lower value of malondialdehyde both before and after the heat stress were documented in fish fed with zinc at 40 mg/kg in diets. After HS, dietary supplementation with zinc threonine significantly reduced the expression of HSP 70 in the liver but increased the expression of IL-10 and TNF-α. Our study demonstrated that zinc threonine supplementation at 40 mg/kg facilitated the coping of tilapia with HS by improving the growth, intestinal morphology, antioxidative resistance, and immune responses. [ABSTRACT FROM AUTHOR]

A comparative feeding trial and digestibility determination were conducted to evaluate the nutritional value of a commercial, high-protein distiller's dried grains with solubles (HP-DDGS) ingredient in the diet of Nile tilapia (Oreochromis niloticus). For the feeding trial, six diets were formulated to contain 360 g total dietary protein kg-1 and were prepared with incremental levels of protein from the HP-DDGS (0, 75, 150, 225, 300, and 375 g of dietary protein kg-1) replacing protein from fishmeal and soybean meal. Juvenile tilapia (10.4 g ± 0.37 ; average initial weight ± SD) were evenly distributed in 24, 38-L aquaria operated as a recirculating system and fed twice daily to apparent satiation throughout the 8-week trial. Nile tilapia exhibited no significant (P > 0.05) differences in weight gain, feed efficiency, condition indices, whole-body proximate composition, or innate immunological responses when fed any DDGS-supplemented diets compared to the control diet. Percent apparent digestibility coefficients (ADCs) of the DDGS product for organic matter, crude protein, and gross energy were 74.8%, 83%, and 82.8%, respectively. Availability values for all amino acids were 89% or greater. Thus, this high-protein DDGS was established as a readily digestible protein feedstuff suitable for replacing soybean meal and fishmeal at up to 375 g of total dietary protein kg-1 in a practical diet for Nile tilapia. [ABSTRACT FROM AUTHOR]

The experiment was performed to examine the effect of Lactobacillus paracasei l61‐27b (LP) isolated from Nile tilapia intestine on the growth rate, skin mucus and serum immune parameters and disease resistance. Fish (25.40 ± 0.33 g) were distributed into glass tank (150 litres tank−1) at 20 fish tank−1 and fed with different levels of dietary L. paracasei l61‐27b: 0 (LP1), 106 (LP2), 107 (LP3), 108 (LP4) and 109 CFU mL−1 (LP5) for 8 weeks. The results indicated that SGR, WG and FW significantly improved, while FCR significantly decreased, in fish fed LP supplemented. Dietary L. paracasei significantly increased SMLA and SMPA with the highest values recorded for fish in LP4 and LP5 groups. Similarly, SL, SP, ACH50, PI and RB were significantly stimulated in fish fed LP diet compared with fish fed control diet. Challenge study showed that in comparison with the control diet (20% survival), the survival rates of fish fed the L. paracasei were significantly (p < 0.05) higher; by 63.33% (LP2), 66.67% (LP3), 80.00% (LP4) and 83.33% for LP5. The relative per cent survival (RSP) was 54.17%, 58.33%, 75% and 79.17% in LP2, LP3, LP4 and LP5, respectively. In conclusion, the dietary inclusion of L. paracasei can be potentially used in Nile tilapia to improve its growth and health status. [ABSTRACT FROM AUTHOR]

This investigation was performed to assess the influences of the host‐associated probiotic Bacillus altitudinis B61‐34b (BAA) on growth, immune response and disease resistance to Streptococcus agalactiae in Nile tilapia (Oreochromis niloticus). Fish (25.50 ± 0.52 g fish−1) were distributed into 15 aquaria (150 litres tank−1) at density of 20 fish tank−1. The fish were fed basal diets with BAA inclusions in different concentrations: 0 (BAA1—Control), 106 (BAA2), 107 (BAA3), 108 (BAA4) and 109 (BAA5) CFU ml−1 for 8 weeks. A completely randomized design with three replications was used. The results indicated that BAA administration generated greater (p < 0.05) skin mucus and peroxidase activities compared to the control, with maximum levels recorded in BAA4 and BAA5. Higher serum immunities, such as serum lysozyme, serum peroxidase, complement, phagocytosis and respiratory burst activities were observed in the BAA4 and BAA5 dietary groups compared to the control, BAA1, BAA2 and BAA3 diets. The relative percentage of survival, growth performance and FCR were also significantly higher (p < 0.05) in the BAA4 and BAA5 groups. In conclusion, dietary supplementation of B. altitudinis at 108 CFU ml−1 can improve Nile tilapia's growth performance, skin mucus and serum immunities, and disease resistance. [ABSTRACT FROM AUTHOR]

With the development of processing technology, cottonseed protein concentrate (CPC) has been widely used as a new protein source to replace fish meal in aquaculture. But whether CPC can replace soybean meal still needs investigation. A ten‐week experiment was designed to evaluate the impact of replacing soybean meal (SBM) protein with CPC at different levels (CPC0 [0%], CPC15 [15%], CPC30 [30%], CPC45 [45%], CPC75 [75%] and CPC100 [100%]) on Nile tilapia (Oreochromis niloticus). The results showed that 45% or higher CPC substitution significantly retarded the growth performance. Increased intestinal permeability was found in the CPC75 and CPC100 treatments. To investigate whether the residual gossypol is account for the intestinal dysfunction, an 8‐week feeding trial including a control diet (CON), a control diet supplemented with 150 mg/kg gossypol (ML) and 300 mg/kg gossypol (MH) treatments, was conducted. The results showed that the transepithelial resistance (TER) was significantly decreased in MH treatment. In conclusion, the replacement of 30% SBM protein by CPC can be used for Nile tilapia's dietary needs, while 45% or higher CPC substitution of SBM influenced the intestinal health and growth condition of Nile tilapia. [ABSTRACT FROM AUTHOR]

Two diets were formulated, a low lysine (LowL) and a balanced lysine diet (BalL), containing 9.10 and 13.10 g lysine kg−1 feed, respectively. Twenty fish (30.2 ± 1.9 g) per tank were stocked in 110‐L tanks, mounted in a recycling aquaculture system (RAS), and nine hundred fish (17.2 ± 1.6 g) per pond were stocked in 200 m2 fertilized ponds (FPS). Four replicates in RAS and five replicates in FPS were assigned for each diet tested. Fish were fed with the experimental diets at a feeding rate based on metabolic body weight, twice daily for 70 days. Fish fed the BalL diet in RAS had a higher yield (kg m−3), specific growth rate, nitrogen retention efficiency (%), protein efficiency ratio (g g−1 protein), protein content and essential amino acid content, as well as a better feed conversion ratio (p <.05). Lysine levels did not significantly affect fish survival (%), feed intake and apparent digestibility coefficients of nutrients. In contrast, in FPS, dietary lysine content did not (p >.05) affect the growth indices of nutrient utilization, survival (%), body composition and essential amino acids or nitrogen utilization efficiency. Percentage compositions of plankton in the gut contents and plankton abundances in water were approximately the same between diets. The Pearson correlation coefficient (r) between plankton abundance and growth in fish fed the LowL diet was.761 and −.961 for phytoplankton and zooplankton, respectively, compared with.50 and.54 in fish fed the BalL diet. The contribution of the natural food to nitrogen gain was 30% in fish fed the LowL diet, compared with 21% in fish fed the BalL diet (p <.05). The present study shows that natural food compensated for the deficiency of dietary lysine and improved the protein efficiency ratio by 46%, when compared to Nile tilapia grown in clear‐water tanks. [ABSTRACT FROM AUTHOR]

Fish meal (FM) is a significant source of protein, but the high cost has limited its use in feeds. Hence, alternative, economic and available FM substitutes should be found. In this study, the consequences of replacing FM with rice protein concentrate (RPC) on the growth parameters, proximate body composition, digestive and absorptive capabilities, biochemical parameters and the expression of appetite‐related gene (ghrelin) in Nile tilapia, Oreochromis niloticus, were investigated. Fish (27.8 ± 0.1 g) were randomly organized into four groups and fed on experimental diets having four replacement percentages of FM with RPC: 0%, 25%, 50% and 75% (RPC0, RPC25, RPC50 and RPC75) for 5 months. The results cleared that RPC25 group exhibited linearly and quadratically the highest values for growth parameters, growth hormone level, and activities of protease, amylase as well as proximal intestinal villus length, width, the goblet cells count and ghrelin gene expression among all groups. From overall results, RPC could be used as an economically and beneficial ingredient to replace up to 25% of dietary FM in Nile tilapia diet with enhancing the growth performance, digestive and absorptive capability, and health status, but with the supplementation of synthetic amino acids. [ABSTRACT FROM AUTHOR]

In this study, we evaluated the growth performance, body composition and feed efficiency, muscle and gut histology, blood haematology and plasma biochemical parameters and the activity of antioxidant enzymes in the liver of Nile tilapia fed diets supplemented with betaine. Increasing doses (0.00, 0.50, 1.00 and 2.00 g kg−1) were added to a basal diet and randomly assigned to three groups, composed of 12 fish (27.76 ± 1.31 g) in each experimental units. The fish were fed to satiation four times a day during 100 days. Dietary inclusion of 0.50 g kg−1 of betaine resulted in greater results in weight gain, daily weight gain, specific growth rate, as well as energy retention rate. Dietary inclusion of betaine resulted in less height, width and thickness of the tunic of the gut folds. Fish fed 0.50 and 1.00 g kg−1 of dietary betaine showed higher plasma glucose. The concentration of substances reactive to thiobarbituric acid was lower in fish fed with 0.50 g kg−1 of dietary betaine, while those fed with 1.00 g kg−1 dietary betaine show greater activity of the catalase enzyme. The dietary inclusion of 0.50 g kg−1 of betaine improves growth performance probably by reducing lipid peroxidation. [ABSTRACT FROM AUTHOR]

Lipid metabolism is a key biological process involving the synthesis and degradation of lipids in organisms. In the liver, triglyceride (TG) synthesis mediates the storage of fats for energy, which is catalysed by diacylglycerol acyltransferase‐2 (DGAT2). Herein, we compared TG‐related indexes in serum from Nile tilapia (Oreochromis niloticus), blue tilapia (O. aureus) and hybrid offspring (Nile tilapia ♀ × blue tilapia ♂). The results showed that serum TG levels were significantly higher in the hybrid tilapia (6.95 ± 1.48 mmol/L) than that in blue tilapia (4.39 ± 1.02 mmol/L). Tissue distribution analysis suggested that DGAT2 was mainly expressed in the liver and muscle. Furthermore, hybrid tilapia exhibited higher mRNA expression of DGAT2 in the liver than the parents. Additionally, the allelic gene expression assay indicated that the alleles of DGAT2 gene from the two parental species were expressed at equal levels. To elucidate the epigenetic regulation of DGAT2 gene expression, the DNA methylation levels at the putative promoter region of DGAT2 in hybrid tilapia and its parents were compared. We found lower DNA methylation levels at the putative promoter region of DGAT2 in hybrid tilapia as compared to the paternal species in liver. DNA methylation levels in the putative promoter region were negatively correlated with DGTA2 expression in tilapia. Three CpG sites were significantly correlated with DGAT2 expression in tilapia. Overall, the present evidence suggests that DNA methylation is associated with the elevated expression of DGAT2 in hybrid tilapia. These results provide new evidence for epigenetic regulation of genes in hybrids, which may aid to understanding of heterosis for fish hybridization breeding and superiorities of nutrient utilization in hybrids. [ABSTRACT FROM AUTHOR]

The combined probiotics (four different combination of Bacillus subtilis, Bacillus licheniformis and Enterococcus faecalis) were used and the growth performance, immunity, gut morphology and resistance to Streptococcus agalactiae of tilapia (Oreochromis mossambicus) were comprehensively evaluated after 42 days feeding on supplemented diets. Results showed that the growth performance of tilapia in PG2 (with B. subtilis and E. faecalis) was the best. Moreover, the strong positive association of some indices with specific probiotics was demonstrated for lipase activity, SI, LYZ, C3, T‐AOC and CAT were higher in PG2, indicating that the specific probiotics, and not diversiform probiotics, were the key determinants of the results for tilapia. The better gut villi length, villi width and muscular thickness in fishes under PG2, which shows that specific probiotics can promote the good development of gut mucosal structure of tilapia. Over 76% survival rate for tilapias against S. agalactiae in the PG2 may be because the B. subtilis and E. faecalis provided a better gut micro‐ecological environment. Totally, B. subtilis and E. faecalis may be specific to tilapia gut microbes. [ABSTRACT FROM AUTHOR]

We evaluated the growth, gut histomorphometry, selected immune responses and resistance of Nile tilapia (Oreochromis niloticus) against Streptococcus agalactiae infection when fed VILIGEN™, an additive blend containing sodium butyrate, dehydrated hydrolysed yeast and zinc proteinate. Increasing doses (0.00, 0.60, 1.20, 2.40 and 4.80 g kg−1) were added to a basal diet and randomly assigned to six groups, each with 28 fish. The fish were fed to satiation twice daily for 60 days, infected via gavage with S. agalactiae at 1.0 × 109 CFU ml−1, and mortality was recorded for 14 days. Dietary inclusion of VILIGEN™ promoted higher weight gain, gut‐fold perimeter and the number of goblet cells. Through polynomial regression, the optimal inclusion level for these variables was estimated at 2.80, 3.30 and 3.50 g kg−1, respectively. However, there was no clear effect of the additive on the immune responses tested before bacterial infection or in the survival after challenge. This is the first study on VILIGEN™ supplementation in fish diets. Higher growth and altered gut morphology were seen with the inclusion of VILIGEN™ in the range of 2.80 to 3.50 g kg−1 but the response to the bacterial challenge was not clearly affected. [ABSTRACT FROM AUTHOR]

An indoor feeding trial was conducted to optimize the amino acid (AA) profile of the genetically improved farmed tilapia (GIFT) diet using the AA deletion method. Six corn–soy‐based isonitrogenous and isoenergetic fishmeal‐free diets with different AA profiles were formulated to evaluate the effects of crystalline AA supplementation on the growth performance, whole‐body composition, muscle growth‐related gene expression and haemato‐biochemical responses of juvenile GIFT tilapia. Each diet was randomly assigned to triplicate groups of 30 fish (5.5 ± 0.3 g) per experimental unit, which were fed three times a day (09:00, 13:00 and 17:00 h) for a period of 60 days. Maximum growth performances and feed utilization were observed in fish fed a balanced diet and a ‐Trp diet compared with the AA‐unsupplemented diet, whereas no significant differences were observed among fish fed –Met, –Lys and –Arg diets. Whole‐body proximate composition and amino acid profile of GIFT tilapia were not significantly affected by diets with different amino acid profiles. Similarly, no significant differences were observed in blood biochemical responses, except glucose. However, significant (p <.05) differences were observed in haematological responses and mRNA expression of MyoD,myogenin and myostatin. Based on the growth performance and feed efficiency, the EAA pattern associated with –Trp diet was considered to be the optimum EAA ratio for maximum growth and feed utilization of juvenile GIFT tilapia. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the dietary total aromatic amino acid requirement and tyrosine replacement value for phenylalanine for fingerling Oreochromis niloticus by conducting two 8‐week experiments. In experiment I, phenylalanine requirement was determined by feeding test diets (350 g kg–1 CP; 16.72 kJ g–1 GE) with graded levels of phenylalanine (4, 6.5, 9, 11.5, 14 and 16.5 g kg–1 dry diet) at a constant level (10 g kg–1) of dietary tyrosine to triplicate groups of fish (1.65 ± 0.09 g). Quadratic analyses of absolute weight gain (AWG), protein deposition (PD%) and phenylalanine retention efficiency (PRE%) indicated the requirement at 12.1 g kg–1 dry diet. In experiment II, six diets with different levels of L‐tyrosine (2.0, 4.0, 6.0, 8.0, 10.0 and 12.0 g kg–1 dry diet) with 12.1 g kg–1 phenylalanine as determined in experiment I fixed in all the test diets were fed to fish (1.67 ± 0.17 g) to determine the tyrosine requirement under same conditions. Quadratic regression analysis of AWG, PD and PRE demonstrated the tyrosine requirement at 8.5 g kg–1 dry diet, corresponding to 24.2 g kg–1 of dietary protein. Based on the above data, the total aromatic amino acid requirement was found to be 20.6 g kg–1 of dry diet, corresponding to 58.8 g kg–1 of dietary protein, and tyrosine replacement value for phenylalanine was found to be 37% on a molar basis. [ABSTRACT FROM AUTHOR]

Zn is one of the essential elements to maintain normal fish metabolic process (including growth, development and reproduction), which have different chemical status in nature including inorganic, organic and nano‐sized. In this work, the efficacy of gluconic acid zinc (Glu‐Zn), nano zinc oxide (Nano ZnO), zinc sulphate (ZnSO4) on the growth performance, tissue mineral elements deposition, antioxidant activity and immune response of the tilapia fish Nile tilapia (Oreochromis niloticus) was evaluated. Three experimental diets were prepared by adding different forms of Zn sources (ZnSO4 as a control group) with same Zn concentration (40 mg/kg) and used to feed fish for 60 days. The biological trial results displayed that the growth performance of Nile tilapia has not obviously affected by different Zn form source supplement. However, Glu‐Zn and Nano ZnO supplements have significantly stimulated the Zn and Cu absorption deposition efficiency in the fish tissues as compared to ZnSO4 group. Besides, there was a significant increase in Cu‐Zn superoxide dismutase (35.03 U/mgprot), alkaline phosphatase (79.34 U/mgprot), aspartate aminotransferase (23.42 U/L), alanine aminotransferase (18.45 U/L), glutathione peroxidase (171.24 U/mgprot) and fatty acid synthase (11.55 ng/mL) content in Glu‐Zn treatment. Additionally, Glu‐Zn supply significantly increased serum lysozyme (9.91 U/mL), immunoglobulin M (0.48 g/L), complement 3 (0.74 g/L) and complement 4 (0.95 g/L) activity of Nile tilapia. Also, compared to ZnSO4 diet, lysozyme (11.44 U/mL) and complement 4 (0.63 g/L) content were obviously higher in fish fed Nano Zn diet. These findings revealed that supplementation with Glu‐Zn as a Zn source in feed is better than ZnSO4 for improving tissue mineralization, antioxidant stress, alleviate lipid peroxidation and immunity response of Nile tilapia. Meantime, Nano ZnO also played a positive role in the tissue mineralization and immunity response of Nile tilapia. [ABSTRACT FROM AUTHOR]

The study was designed to evaluate the effects of total remplacement of fish meal (FM) and fish oil (FO) by vegetable oil and black soldier fly (BSF) larval meal enriched with fatty acids (FAs) in Nile tilapia juveniles. Fish were fed a FMFO control diet compared to a non‐FA‐enriched BSF diet (BSF/T0) and diets enriched in linolenic acid‐ALA (BSF/T1) or in eicosapentanoic acid‐EPA (BSF/T2). After 59 days, the BSF diets did not affect growth except for a decrease by the BSF/T1 diet. However, protein utilization and digestibility were reduced by all the BSF diets. FA‐enriched diets did not improve the digestive enzyme activities or immune parameters, while lysozyme and ACH50 values were increased by the BSF/T0 diet. Levels of polyunsaturated FAs in the whole body of fish fed ALA or EPA‐enriched BSF diets were comparable to those of FMFO controls. The results demonstrate that BSF meal can totally replace FM without substantially effect on growth or innate immune status. The decrease in fish carcass FA quality induced by the BSF meal can be prevented by a well defined protocol for PUFA enrichment. Nonetheless, investigation of the long‐term effects of the BSF meal use during the ongrowing phase is still needed. [ABSTRACT FROM AUTHOR]

Fish were fed diets containing dehydrated ginger powder (GgP) to determine its effects on growth, immune response, antioxidant capacity and resistance to Aeromonas hydrophila infection. 540 Nile tilapia were distributed in 36 250 L aquaria and fed six isonitrogenous and isoenergic diets supplemented with six graded levels of GpP: 0, 2.5, 5, 7.5, 10 and 15 g/kg, during 30 days. After that, growth, hemato‐immunological parameters and antioxidant enzymes activities were determined. All parameters, but growth, were re‐evaluated after the bacterial infection challenge. Fish fed diets up to 5 GgP showed higher body weight and specific growth rate compared with 0 GgP. Fish fed 10 GgP showed the highest H2O2 and NO compared with 0 GgP (p <.05). Fish fed 2.5 GgP and 10 GgP maintained catalase and superoxide dismutase activities after infection. The highest survival was observed for fish fed 10 GgP. The best results for specific growth rate and feed conversion ratio were determined at 4.1 and 5.8 g/kg of GgP and for survival rate and immunological response at 10 g/kg of GgP. In sum, 10 g/kg GgP is indicated to improve Nile tilapia growth performance and resistance against Aeromonas hydrophila infection. [ABSTRACT FROM AUTHOR]

The present study evaluated the effects of a commercial soy lecithin‐containing bioemulsifier Lysomax® on growth performance, feed utilization, haematology, immune response and gut histology of adult Nile tilapia (Oreochromis niloticus) fed soybean meal‐based diets, containing plant oil as a lipid source. This emulsifier was incorporated into four isonitrogenous (30% cp), isocaloric (17.5 MJ/kg) test diets, at 0 (control), 0.3, 0.6 and 0.9 g/kg feed. The diets were fed to triplicate groups of adult Nile tilapia, reared in a closed recirculating indoor system, at a daily rate of 3% of fish live weight, twice a day for 60 days. Growth rates, feed utilization efficiency, digestive enzymes activities, blood parameters, liver function enzymes and immunological responses were all boosted (p <.05) with increasing supplemental Lysomax up to 0.3 g/kg diet, followed by a significant retardation (p <.05) at 0.6 and 0.9 levels. Muscle n‐6 and n‐3 polyunsaturated fatty acids (PUFA) and n3/n6 ratio were also increased with increasing Lysomax up to 0.3 level and then levelled off with further increase in dietary Lysomax. The highest length and width of the intestinal microvilli and goblet cell counts were also found in the fish fed on 0.3 g Lysomax/kg diet. However, the quadratic regression analyses of the obtained results indicated that the maximum performance occurred at about 0.45 g/kg of dietary Lysomax. These results suggest that lecithin‐containing bioemulsifier Lysomax® can play a significant role in feed digestion and absorption and improving fish performance and innate immune response. About 0.45 g/kg diet would be sufficient for best performance and health status of farmed Nile tilapia. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of lysine and histidine supplementation on growth performance, gene expression, blood parameters and quality of the fillet in Nile tilapia, Oreochromis niloticus (n = 192; 136.14 ± 2.32 g). Fish were distributed into four groups and fed a control diet without lysine and histidine supplementation (CON), supplemented with lysine (LYS), histidine (HIS) or lysine and histidine (LYS + HIS) and fed until apparent satiety for 90 days. Growth performance increased significantly in fish fed diet LYS + HIS (p <.05). The fillet body weight gain and fillet yield increased by 26.61% and 2.74% unit, respectively, compared to fish fed CON diet (p <.001). Compared to the control group, fish fed diets showed decreased whole‐body lipid and plasmatic triglycerides coupled to increased mRNA levels of MyoD and myogenin in the skeletal muscle and higher texture attributes of fillets (p <.05). There was a substantial negative correlation between body lipids and hardness of fillets. Overall, the combined supplementation of lysine and histidine optimizes growth performance, expression of muscle growth‐related genes and flesh quality attributes in grow‐out Nile tilapia. [ABSTRACT FROM AUTHOR]

This study was carried out to evaluate the effects of water temperature (WT) and dietary protein levels on growth, body composition and blood biochemistry of GIFT tilapia (Oreochromis niloticus; initial average body weight: 38.75 ± 0.61g, n = 20). The fish were fed with six diets contained graded levels of protein (209.6, 251.0, 302.4, 354.3, 401.9 and 456.8 g/kg) and raised in each of WT (22°C, 28°C and 34°C) for 8 weeks. Results showed that the growth, feed utilization and protein efficiency were significantly increased with the increase of dietary protein level and followed by the latter platform at each WT. The fish raised at 28 and 34°C showed similar growth performance, and their values were significantly higher than the fish raised at 22°C (p < 0.05). The lipid contents in whole body were decreases with the increase of dietary protein level at each WT. However, the whole‐body protein, ash and moisture contents were not affected by dietary protein level or WT (p > 0.05). The values of serum biochemical indices (ALP, ALT, AST and TCHO) were all decreased with the increase of dietary protein. The optimal dietary protein requirement for GIFT tilapia to achieve maximal growth performance is 374.4, 301.7 and 304.9 g protein/kg diet at 22, 28 and 34°C, respectively. [ABSTRACT FROM AUTHOR]

Thirty groups of twenty juveniles each of Nile tilapia (Oreochromis niloticus, initial average weight 23.93 ± 0.80 g) were fed diets containing increasing amounts (0%, 25%, 50%, 75%, and 100% of levels used by the tilapia feed industry) of organic trace mineral (Fe, Zn, Mn, Cu, Se) supplementation for 56 days. Growth was not affected by the dose of mineral supplementation. However, body protein increased in fish fed intermediate doses of organic minerals, reaching a maximum at 40.44% supplementation. Doses >50% showed mild damage to the intestinal tissue. Body Fe, Zn and Cu deposition were highest at 28.32%, 24.43% and 78.45% supplementation, respectively. Tilapia could modulate intestinal morphology when fed different doses of organic minerals. As the supplementation doses increased, hemosiderin staining increased in the distal intestine and total body Fe content, indicating that the distal region of the intestine plays an important role in iron excretion by tilapia. Supplementation of organic trace minerals at intermediate doses does not harm Nile tilapia growth, but excessive trace mineral supplementation can impair body protein retention and promote histological alterations in the gut. [ABSTRACT FROM AUTHOR]

In the winter of south China, low water temperatures resulted in a large‐scale mortality of tilapia, which is a tropical fish and sensitive to cold. How can we solute the problem? The growth performance, antioxidation and gene expression of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) juveniles in cold freshwater were investigated by feeding various dietary vitamin E (VE) or/and alanyl‐glutamine dipeptide (AGD) supplementation. Seven groups of the juveniles in triplicate were reared in tanks, with 120 L volume and 38 fish each tank, using exposed, filtered and aerated tap‐water. One group of the juveniles was reared in 28°C (normal water temperature control and marked as D0′) and another six groups of the juveniles in 18°C (cold water, one marked as cold water control, D0, and five marked as D1–D5). The GIFT tilapia juveniles were fed twice daily using one of six specific diets: control diet (D0′, D0) without additive; diets 1 to 5 were added different doses of VE or/and AGD based on per kg of dried feed. Diet 1 (D1) was added VE 100 IU alone; diet 2 (D2) AGD 10 g only; diet 3 (D3) VE 100 IU and AGD 10 g; diet 4 (D4) VE 50 IU and AGD 5 g; diet 5 (D5) VE 25 IU and AGD 2.5 g. The GIFT tilapia juveniles were reared for 12 weeks and sampled randomly for analysis in week 0 and 12. The following parameters in the serum, muscle and liver of the juveniles were determined: the expression of heat shock proteins 70 (HSP70), peroxisome proliferator‐activated receptor α (PPARα) and glutathione peroxidase (GPX) genes, survival rate (SR), relative weight gain (RWG), specific growth rate (SGR), protein efficiency ratio (PER), GPX, superoxide dismutase (SOD) and catalase (CAT), glutathione/glutathione oxidized (GSH/GSSG) and total antioxidant capacity (T‐AOC). The above‐mentioned parameters in the serum, muscle and liver of the D0 juveniles (18°C control) were lower significantly (p <.05) than those of the D0′ juveniles (28°C control). However, the above‐mentioned parameters were considerably promoted by feeding various additional dietary VE or/and AGD, in which the highest HSP70, PPARα and GPX gene expression, SR, RWG, SGR, PER, antioxidases, GSH/GSSG and T‐AOC were found in the liver, muscle and serum of the juveniles fed D3 and differed significantly from those of the juveniles fed other diets, respectively. In concluded, D3, with additional VE 100 IU and AGD 10 g per kg of dried feed, was the optimum diet for juvenile GIFT tilapia in 18°C freshwater. [ABSTRACT FROM AUTHOR]

The current study was designed as (2 × 3) factorial groups of 20 and 40 mg Zn/kg diet from each inorganic (zinc oxide), organic (Zn‐methionine) and nanoparticle (nano‐zinc oxide) sources supplemented to six Nile tilapia (O. niloticus) fingerling diets. The results showed both organic and nano‐Zn‐administered groups, especially at 40 mg/kg, exhibited significant improvements in body weight, total gain, feed conversion ratio and specific growth rate as compared to inorganic Zn‐supplemented groups. Nano‐Zn, at 20 and 40 mg/kg diet, increased haemoglobin, WBC counts, as well as lysozyme, IgM, and serum bactericidal test compared with other sources. Increasing Zn levels progressively increased serum and muscle Zn contents in nano‐Zn groups. Antioxidant capacity (TAC, SOD, and CAT) also increased in nano‐Zn‐supplemented fish at 40 mg/kg diet. Although the mRNA expression profile of growth hormone (GH) and insulin‐like growth factor 1 (IGF‐1) showed an up‐regulation in both organic and nano‐Zn‐supplemented fish, a dose‐dependent up‐regulation was observed for the expression of hepatic antioxidant (SOD and GPx) and immune (IL‐1β and TNF‐α) encoding genes in nano‐Zn‐administered groups alone. The highest resistance against Aeromonas hydrophila was observed in the nano‐Zn‐supplemented group at 40 mg/kg diet. Thus, it can be concluded that zinc nanoparticles are potential alternatives to conventional zinc sources in Nile tilapia. [ABSTRACT FROM AUTHOR]

This study investigated the effects of dietary exogenous protease on the growth performance, intestinal health, immune parameters and disease resistance of genetically improved farmed tilapia (GIFT, Oreochromis niloticus). Five test diets with commercial protease at the levels of 0, 1.38, 2.76, 5.52 and 11.04 U/g (named PE0, PE1, PE2, PE5 and PE11, respectively) were administered to triplicate tanks with 30 fish for 60 days, and then, the fish were challenged with Streptococcus agalactiae for 14 days. The results indicated that weight gain increased as exogenous protease increased from 0 to 5.52 U protease/g diet and then decreased significantly (p <.05) with a further increase in exogenous protease supplementation (p <.05). The height of the villi in the proximal intestine and distal intestine, the width of the villi in three segments of the intestine, and the thickness of the muscle layer in the proximal intestine and mid‐intestine (p <.05) were increased in the fish fed the PE5 diet. Immune and antioxidant indices (except malondialdehyde), and survival after challenged with S. agalactiae were higher in fish fed PE5 diets than in those fed other diets (p <.05). In conclusion, 5.52 U/g protease supplementation in a plant‐based diet could promote the growth performance, intestinal physical barrier function, innate immunity and S. agalactiae resistance of GIFT. [ABSTRACT FROM AUTHOR]

A 60‐day indoor feeding trial was conducted to evaluate the effects of dietary tryptophan supplementation on growth performances, whole‐body chemical composition, expression of muscle growth‐related genes (MyoD, myogenin and myostatin), and haematological and biochemical responses of juvenile genetically improved farmed tilapia (GIFT). Five corn–soy‐based isonitrogenous and isoenergetic diets were formulated to contain graded levels of dietary tryptophan (2.6, 3.2, 3.7, 4.2 and 4.8 g/kg of diet). Each diet was randomly assigned to triplicate groups of 30 fish (5.3 ± 0.1 g) per experimental unit, which were fed thrice a day (9:00, 13:00 and 17:00 hr). Maximum growth performances and feed utilization were observed in fish fed tryptophan at 3.7 g/kg of diet. There was no significant (p >.05) effect on whole‐body composition and amino acid profile by dietary tryptophan supplementation. However, significant (p <.05) differences were observed in plasma metabolites and the mRNA expression of MyoD, myogenin and myostatin. Serum cortisol level was found significantly lowest in fish fed tryptophan at 3.7 g/kg of diet. Second‐order polynomial regression analysis of weight gain and nitrogen gain against dietary tryptophan levels indicated that the optimum dietary tryptophan requirement for maximum growth and feed utilization of juvenile GIFT tilapia was 3.8 g/kg of diet. [ABSTRACT FROM AUTHOR]

Nile tilapia (1.20 g) were fed for 56 days in five treatments (FM100 containing only fish meal [FM] as a protein source; soybean meal (SBM) replace 25%, 50%, 75% and 100% of FM protein in the diets of FM75, FM50, FM25 and FM0, respectively) to assess the effects of dietary protein sources on growth, turnover half‐life of nitrogen and carbon stable isotopes (δ13C and δ15N) in muscle, isotope discrimination factors (Δ15N and Δ13C), and the relative contribution of protein sources to muscle growth. Results showed that the final body weight, weight gain and specific growth rate of fish fed diet FM25 were significantly higher than other treatments (p <.05). By day 35, fish under all treatments reached isotopic equilibrium, and the equilibrium values consistently increase as a function of stable isotope values in diets. Growth accounted for most isotopic changes in muscle and resulted in significantly shorter half‐lives of nitrogen and carbon in FM25 (p <.05). The Δ15N of FM25 and Δ13C of FM0 were significantly lower than other treatments (p <.05). The proportional contributions of SBM protein were significantly higher than their respective levels in FM75 and FM25 (p <.05), indicating a preferential incorporation of nitrogen from the SBM in muscle tissue. [ABSTRACT FROM AUTHOR]

A study was conducted to characterize the effects of dietary oxidized fish oil on the growth performance, immunity and antioxidant status of genetically improved farmed tilapia (Oreochromis niloticus) and to determine the role of ferulic acid on the oxidative damage induced by the oxidized fish oil. The tilapia (13.73 ± 0.31 g) were fed four experimental diets containing untreated (peroxide value, POV: 2.2 meq/kg) and highly oxidized (POV: 120.6 meq/kg) fish oil either with or without ferulic acid (0 or 400 mg/kg) supplementation for 12 weeks. From the results, the oxidized fish oil treatments increased antioxidant enzyme activities and MDA values but decreased the weight gain and the immunological parameters in tilapia. Meanwhile, the serum biochemical indices were significantly affected by the oxidized fish oil. Besides, the addition of ferulic acid partially counteracted the free radical‐induced damage and improved the health status of tilapia. In conclusion, the oxidized fish oil may induce oxidative stress, destroy liver, dysregulate lipid metabolism as well as reduce non‐specific immunity, and eventually result in growth inhibition of tilapia. The ferulic acid supplementation partially offset the negative effects of the oxidized fish oil on tilapia. [ABSTRACT FROM AUTHOR]

The present research explored the effects of Bacillus subtilis on water quality, growth, immune responses, endotoxemia and protection against lipopolysaccharide (LPS) damages in Nile tilapia Oreochromis niloticus under biofloc system. B. subtilis was added at 0, 1, 2, 3 and 4 grams (1.19 × 108 CFU/g) per kg of basal diet, named T1 (control), T2, T3, T4 and T5, respectively, and fed to fish (14.82 ± 0.42 g) for 50 days. The concentrations of TAN, NO2 and NO3 were significantly reduced, and fish fed probiotics displayed significantly better growth performances versus the control, concomitantly with significantly enhanced activities of digestive enzymes. They also showed significantly declined serum glucose and cholesterol vice versa significantly improved immune responses (total protein, albumin, globulin, lysozyme, alternative complement, protease, immunoglobulins, alkaline phosphatase and respiratory burst), antioxidant capacity (superoxide dismutase, total antioxidant capacity, malondialdehyde) and skin mucus parameters (total protein, lysozyme, alternative complement, protease, immunoglobulins). Meanwhile, significantly lower endotoxin (LPS) concentrations were detected in the intestines and serum of fish fed probiotics. LPS challenge induced profound oxidative stress and impaired immune responses. Interestingly, probiotic alleviated LPS‐induced damages and restored mentioned parameters. In conclusion, B. subtilis effectively enhanced fish production, immunity and protection against LPS‐induced damages in tilapia under biofloc system. [ABSTRACT FROM AUTHOR]

The present study was conducted to administer a commercial multi‐strain probiotic (MP), Yilibao (Bacillus velezensis:Bacillus cereus:Lactobacillus casei = 2:2:1), in Nile tilapia, Oreochromis niloticus. In terms of aerobic Bacillus spp. counts, we produced five diets containing 0, 0.34, 1.68, 3.36 and 6.72 g/kg of MP dry product (Control, T1, T2, T3, T4). Seven hundred and fifty tilapia juveniles (13.26 ± 0.01 g) distributed into 25 tanks in five replications were fed their diet for eight weeks. Results showed that fish fed T3 and T4 diets displayed significantly higher final body weight and weight gain (p <.05). Further, all MP‐treated fish exhibited remarkably decreased plasma lipid profiles (cholesterol, triglycerides) (p <.05) and fish fed T3 and T4 diets displayed significantly higher plasma myeloperoxidase activity and complement C3 content (p <.05). Additionally, fish fed T3 and T4 diets exhibited significantly promoted total antioxidant capacity, glutathione peroxidase activity, glutathione level and declined malondialdehyde content in the plasma and/or liver (p <.05). Moreover, significantly elevated chymotrypsin activity, villus height and intraepithelial lymphocytes counts were found in fish fed T3 and T4 diets (p <.05). As fish fed T3 and T4 diets surpassed the other treatments in growth, immune–antioxidative status and gut health, the recommended dose for tilapia is 3.36–6.72 g/kg. [ABSTRACT FROM AUTHOR]

The optimum water temperature required for the normal growth of Nile tilapia is 25–30°C. In this study, tilapia was reared under suboptimal temperature (21.50 ± 1.50°C) and fed four diets with fish oil (FO), corn oil (CO), sunflower oil (SFO) and linseed oil (LnO) for 8 weeks. The results revealed improved final weight, average daily gain and intestinal amylase activity in the LnO group compared to FO and SFO groups (p <.05). The feed intake was increased significantly in FO and LnO groups compared to CO and SFO groups, while the feed conversion ratio was increased in the FO group (p <.05). The CO, SFO and LnO diets resulted in higher carcass lipids than fish fed FO, while CO decreased the ash content (p <.05). The growth hormone was significantly lowered by LnO, followed by SFO, while CO improved the serum alkaline phosphatase activity (p <.05). Glutathione peroxidase enhanced in fish fed SFO, while the lowest activities were recorded in fish fed FO (p <.05). Total superoxide dismutase was significantly elevated by CO and LnO when compared with fish fed FO and SFO (p <.05). Substituting FO with vegetable oils had normal intestinal and liver histological appearance. It could be concluded that substituting FO with either CO or LnO for Nile tilapia could maintain the normal growth performance and feed utilization with enhanced antioxidant capacity under suboptimal temperature. [ABSTRACT FROM AUTHOR]

Five diets were prepared to include date palm seed meal (DSM) fermented with Aspergillus oryzae (ASP) at 0, 50, 100, 150 and 200 g/kg diet and fed for Nile tilapia (26.93 ± 0.01 g) for 8 weeks. Fermented DSM significantly affected the final weight, weight gain and specific growth rate in a dose‐dependent manner (p =.001) with insignificant differences in feed conversion ratio (p >.05). Dietary fermented DSM significantly increased the lipase, amylase and protease activities (p =.008, p =.001 and p =.01, respectively) and the Hb, RBCs and WBCs (p =.001, p =.005, and p =.009, respectively). The intestinal villus length and number of goblet cells were significantly affected by fermented DSM inclusion (p <.05). Additionally, the total protein, albumin and globulin significantly affected by the inclusion of fermented DSM in a dose‐dependent manner (p =.04, p =.045, and p =.03, respectively). Furthermore, dietary fermented DSM significantly altered the phagocytic index, phagocytic activity and lysozyme activity (p =.001, p =.045 and p =.04, respectively). Based on the polynomial regression analysis, the inclusion of fermented DSM at 103.3–164.8 g/kg diet can be used effectively in tilapia diets for improving the growth, digestion activity and immune response. [ABSTRACT FROM AUTHOR]

The feeding trial was conducted to evaluate the potentials of Clostridium butyricum in the diet of tilapia. Fish (~14 g) were fed with basal diet supplemented with 0 (Control), 0.5 (C‐1), 1 (C‐2), 2 (C‐3), 4 (C‐4) and 8 (C‐5) g/kg commercial probiotic‐containing C. butyricum (1.5 × 108 CFU/g) for 8 weeks. The results showed that weight gain significantly increased, and feed conversion ratio decreased in the C‐2, C‐3 and C‐4 groups (p <.05). The protein retention (except C‐1 group), lipid retention and apparent digestibility coefficient (ADC) of dry matter in probiotic supplementation groups were significantly enhanced, and ADC of protein in the C‐4 group was also improved (p <.05). The supplementation of probiotic significantly increased villus height in anterior intestines and reduced the numbers of intestinal Escherichia coli (p <.05). High‐throughput sequencing showed that top three phyla namely Planctomycetes in all probiotic‐containing groups, Proteobacteria in the C‐1 and C‐2 groups and Chloroflexi in the C‐3 group had higher level than the NC group. The cumulative mortality was reduced by dietary probiotic after challenging with Aeromonas hydrophila (p <.05). In conclusion, C. butyricum can be supplemented at 1–2 g/kg feed for promoting the growth, feed utilization, gut health and microbiota of tilapia. [ABSTRACT FROM AUTHOR]

A feeding experiment was conducted to determine the optimum selenium requirement in juvenile Nile tilapia. Each of six purified diets with Se‐methionine levels at 0.05, 0.21, 0.41, 0.57, 0.79 and 1.00 mg/kg was assayed in triplicate with initial body weight of 3.00 ± 0.01 g for 8 weeks. The growth of fish was obviously increased when the dietary Se was less than 0.57 mg/kg diet and reached a plateau when the dietary Se was ≥0.57 mg/kg. Serum and hepatopancreatic glutathione peroxidase (GPx) activity increased markedly when the dietary Se was less than 0.57 mg/kg, but then decreased when the dietary Se was higher than 0.57 mg/kg. The malondialdehyde contents in hepatopancreas were significantly decreased when the dietary Se was higher than 0.79 mg/kg. No significant differences were observed in hepatopancreatic total antioxidant capability (T‐AOC) among the groups (p >.05). The results of this study indicated that Se addition as Se‐methionine was essential, while both the deficiency and excess levels of dietary Se would cause negative effects on growth or antioxidant capability in juvenile Nile tilapia. Based on broken‐line regression of WG and piecewise regression of liver GPx, the optimum requirement of Se for juvenile Nile tilapia is 0.57 mg/kg diet. [ABSTRACT FROM AUTHOR]

Aquaculture is one of the most thriving animal production sectors, and Nile tilapia (Oreochromis niloticus) farming represents 8% of total finfish culture. However, the industry sustainability depends on the development of cost‐effective and environmental friendly feeds. This study aimed to reduce dietary protein levels in diets for juvenile tilapia and to minimize diet environmental impact while maximizing biological efficiency. A growth trial was performed using five isoenergetic plant protein‐based diets with decreasing levels of crude protein: 360, 340, 320, 300 and 280 g/kg diet (D360, D340, D320, D300 and D280, respectively). Dietary protein utilization was assessed by metabolic trials using a radiolabelled amino acid mixture. Tilapia in all treatments showed similar growth performance and feed intake. Feed conversion ratio was significantly higher in fish fed the D280 than the D360 diet, while no differences were found for other treatments. Protein retention was significantly higher in tilapia fed the D300 than the D360 diet. Amino acid catabolism increased in fish fed the D360 diet, though without significant differences in muscle amino acid retention. This study demonstrates that dietary protein levels can be reduced to 300 g/kg diet without hindering tilapia growth and feed conversion ratio, while reducing environmental nitrogen losses. [ABSTRACT FROM AUTHOR]

A two‐factor orthogonal test was conducted to determine the dietary vitamin E (VE, dl‐α‐tocopheryl acetate) requirement for sub‐adult GIFT strain of Nile tilapia (Oreochromis niloticus) at two lipid levels, and evaluate its effect on antioxidant responses. A basal diet containing 60 or 130 g/kg of soybean oil was supplemented with 0, 20, 40, 60, 120 and 240 mg VE/kg, respectively. Each diet was fed to three replicate groups of tilapia with initial weight (80.3 ± 0.7) g for 10 weeks. Results showed that the weight gain, feed efficiency and hepatic VE retention of fish were significantly increased by the increased VE in diets. In groups with 60 and 130 g/kg lipid, fish fed diets supplemented with VE had higher serum superoxide dismutase (SOD) and catalase activity, and lower malondialdehyde content than fish fed the VE un‐supplemented diet (p <.05). The proximate composition of fish had no significant difference in the group with 130 g/kg lipid, whereas crude lipid and ash content were significantly affected by dietary VE in the group with 60 g/kg lipid. Based on broken‐line regression analysis, dietary VE requirement to support the maximum weight gain and serum SOD were 43.2–45.8 and 66.0–76.1 mg/kg in diets with 60 and 130 g/kg lipid, respectively. [ABSTRACT FROM AUTHOR]

To evaluate the effects of dietary cork, protease and guar gum on growth, intestinal health and faecal floatability of tilapia, fine or coarse particle cork (0.45–0.60 mm, 0.60–0.83 mm) was included in diets at 0 (control), 20 g/kg, 30 g/kg and 40 g/kg, and then, 0.175 g/kg protease (P) and 3 g/kg guar gum (G) were supplemented to the 40 g/kg coarse particle diet individually or in combination (P + G). Tilapia with an initial body weight of 15.0 ± 0.5 g were fed one of the 10 diets for 60 days. The results showed that weight gain (WG), apparent digestibility coefficient (ADC) of dry matter (DM) and crude protein (CP), intestinal evacuation ratio, intestinal digestive enzyme activity (IDE) and villus height decreased, and floating faeces ratio increased with the increasing cork level in diets. At the same supplementation level, coarse particle groups showed significantly higher floating faecal ratio than fine particle groups (p <.05). Dietary protease increased the WG, ADC of DM, IDE and villus height (p <.05), and guar gum increased floating faecal ratio when compared to 40 g/kg coarse particle group (p <.05). However, the ADC of DM, IDE and villus height of protease group were still inferior to those of control group (p <.05). In conclusion, dietary cork increased the floating faeces ratio, and the coarse particles produced more floating faeces than fine particles. Moreover, the supplementation of guar gum in cork‐supplemented diet further increased the floating faeces ratio. However, dietary cork negatively affected the growth performance of tilapia, which could be partially alleviated by the supplementation of protease. [ABSTRACT FROM AUTHOR]