Yeast enzyme hydrolysis slurry supplementation improves growth, intestinal health, and metabolic responses in juvenile largemouth bass (Micropterus salmoides) fed soybean meal-based diets with partial fishmeal replacement.

Effects of cottonseed protein concentrate on growth performance, hepatic function and intestinal health in juvenile largemouth bass, Micropterus salmoides

Intestinal flora and immunity response to different viscous diets in juvenile largemouth bass, Micropterus salmoides

Effects of dietary fish meal replacement by Periplaneta americana meal on growth, metabolism, intestinal health and resistance against Aeromonas hydrophila of Micropterus salmoides

A study of the potential effect of yellow mealworm (Tenebrio molitor) substitution for fish meal on growth, immune and antioxidant capacity in juvenile largemouth bass (Micropterus salmoides)

Dietary supplementation of bile acid attenuate adverse effects of high-fat diet on growth performance, antioxidant ability, lipid accumulation and intestinal health in juvenile largemouth bass (Micropterus salmoides)

Simple SummaryNowadays, owing to its limited availability and high cost, fish meal is no longer an affordable protein source in fish feed. Therefore, it is necessary to find new sustainable protein sources to replace fishmeal in the diet of fish or in aquafeeds. Recently, yellow mealworm (Tenebrio molitor) has been widely used as a protein source in the formulated feed of broilers, pigs, shrimp and fish, due to its high protein content, excellent amino acid profile and abundant functional substances. In this study, we found that yellow mealworm meal has high digestibility in largemouth bass (Micropterus salmoides) and an appropriate level (less than 19.52%) in the diet can promote growth and improve liver health in largemouth bass. Therefore, we assume that utilization of yellow mealworm in the diet of largemouth bass as a protein source is feasible.This study investigated the effects of yellow mealworm meal (TM) on growth performance, hepatic health and digestibility in juvenile largemouth bass (Micropterus salmoides). The fish were fed with the basic feed and the test feed (70% basic feed and 30% raw materials) containing Cr2O3, and feces were collected for digestibility determination. The fish were fed with five isonitrogenous (47% crude protein) and isolipidic (13% crude lipid) diets, in which fishmeal (FM) was replaced with 0% (TM0), 12% (TM12), 24% (TM24), 36% (TM36) and 48% (TM48) TM. The fish were reared in cylindrical plastic tanks in a recirculating aquaculture system for 11 weeks. The apparent digestibility coefficients (ADC), of dry matter, crude protein and crude lipid, in largemouth bass of TM were 74.66%, 91.03% and 90.91%, respectively. The ADC of total amino acid (TAA) of TM in largemouth bass was 92.89%, and the ADC of essential amino acid (EAA) in TM in largemouth bass was 93.86%. The final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) in the TM24 group were significantly higher than those in other groups. Similarly, the highest mRNA expression levels of hepatic protein metabolism genes (pi3k, mtor, 4ebp2 and got) and antioxidant enzyme (glutathione peroxidase, Gpx; catalase, Cat) activities were observed in the TM24 group. Moreover, the expression levels of anti-inflammatory factors (il-10 and tgf) in liver were up-regulated and the expression levels of pro-inflammatory factors (il-8 and il-1β) in liver were down-regulated. Quadratic regression model analysis, based on weight gain rate (WGR) against dietary TM level, indicated that the optimum level of dietary TM replacing FM in largemouth bass diet was 19.52%. Appropriate replacement levels (less than 36%) of FM by TM in the diets can enhance the antioxidant capacity and immunity of largemouth bass. However, high levels of FM substitution with TM (more than 48%) in the feeds can damage the liver health and inhibit the growth of largemouth bass. Notably, largemouth bass has high ADC and high utilization of TM, which indicates that it is feasible to use TM as feed protein source for largemouth bass.

The improper components of formulated feed can cause the intestinal dysbiosis of juvenile largemouth bass and further affect fish health. A 28 day feeding trial was conducted to investigate the effect of partially replacing fish meal (FM) with autolyzed Yarrowia lipolytica (YL) on juvenile largemouth bass (Micropterus salmoides). We considered four diets—control, YL25, YL50, and YL75—in which 0%, 25%, 50%, and 75% of the FM content, respectively, was replaced with YL. According to results, the weight gain rate (WGR) and specific growth rate (SGR) of the fish with the YL25 and YL50 diets were significantly higher than the WGR and SGR with the control diet, while the YL75 diet significantly reduced fish growth and antioxidant enzymes activities, and shortened the villus height in the intestinal mucosa. The 16S rRNA analysis of the intestinal microbiota showed that the relative abundance of Mycoplasma was significantly increased with the YL25 and YL50 diets, while the Enterobacteriacea content was increased with the YL75 diet. Moreover, our transcriptome analysis revealed that certain differentially expressed genes (DEGs) that are associated with growth, metabolism, and immunity were modulated by YL inclusion treatment. Dietary YL25 and YL50 significantly reduced the mRNA level of ERBB receptor feedback inhibitor 1 (errfi1) and dual-specificity phosphatases (dusp), while the expression of the suppressor of cytokine signaling 1 (socs1), the transporter associated with antigen processing 2 subunit type a (tap2a), and the major histocompatibility complex class I-related gene (MHC-I-l) were sharply increased with YL75 treatment. We determined that the optimum dose of dietary YL required for maximum growth without any adverse influence on intestinal health was 189.82 g/kg (with 31.63% of the fishmeal replaced by YL), while an excessive substitution of YL for fishmeal led to suppressed growth and antioxidant capacity, as well as intestinal damage for juvenile largemouth bass.

This study aimed to investigate the effects of betaine supplementation in a high-carbohydrate diet on the intestinal health of juvenile largemouth bass ( Micropterus salmoides ). Six diets were formulated: a low-carbohydrate diet (8% corn starch), a high-carbohydrate diet (20% corn starch), and the HC diet supplemented with 0.5%, 1.0%, 1.5%, or 2.0% betaine (HCB1–HCB4). A total of 270 juvenile largemouth bass with an initial body weight of 4.34 ± 0.11 g were subjected to a 56-day feeding trial. The experimental results showed that 0.5% betaine significantly improved the weight gain rate (WGR) and specific growth rate (SGR) of juvenile largemouth bass. In terms of antioxidant capacity, the levels of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) in the intestine were markedly enhanced in the HCB groups, while 1.0% betaine significantly elevated intestinal glutathione (GSH) levels (P < 0.05). Regarding intestinal histomorphology, betaine supplementation improved the intestinal histological structure, significantly upregulated the expression levels of zonula occludens-1 (ZO-1) and Occludin in the intestine, and notably augmented intestinal Claudin-1 expression in the 1% and 1.5% betaine groups (P < 0.05). Furthermore, betaine reduced intestinal mucosal permeability, as evidenced by a significant decrease in serum diamine oxidase (DAO) levels (P < 0.05). Additionally, betaine alleviated intestinal inflammation: specifically, 0.5% and 1% betaine markedly suppressed the expression of nuclear factor kappa-B (NF-κB), interleukin-8 (IL-8), and cyclooxygenase-2 (COX-2), while the expression level of interleukin-10 (IL-10) was significantly upregulated in the HCB groups (P < 0.05). Concomitantly, supplementation with 0.5% betaine significantly boosted the relative abundance of Actinobacteria, whereas supplementation with 1% and 1.5% betaine significantly decreased the relative abundances of Proteobacteria and Enterobacteriaceae (P < 0.05). In conclusion, dietary supplementation with 0.5%–1.5% betaine can significantly improve the intestinal health of juvenile largemouth bass.

Use of fermented tea residues as a feed additive and effects on growth performance, body composition, intestinal enzyme activities, and inflammatory biomarkers in juvenile largemouth bass (Micropterus salmoides)

Multi-omics reveals soybean meal-induced gut microbiota alterations and metabolic disturbances in largemouth bass (Micropterus salmoides): Implications for aquaculture nutrition.

Aquaculture intensification has resulted in serious disease outbreaks in largemouth bass production. Compounds containing copper (Cu) are widely used as therapeutic agents in aquaculture. Currently, Cu misuse has been a severe issue in largemouth bass farming. However, few investigations have been performed on Cu toxicity in largemouth bass so far. In this study, an acute and a chronic toxicity test was carried out to determine the toxicity and the recommended dose of waterborne Cu in largemouth bass. In the acute toxicity bioassay, fish (2.58 ± 0.03 g) were exposed to 0 (control), 3, 6, 9, 18, or 30 mg/L Cu, and the results showed that the 96-h LC 50 of waterborne Cu was 12.78 mg/L. Then a 30-day chronic toxicity test containing six treatments (i.e., 0, 51.3, 164, 513, 1640, and 5130 μg/L Cu) was conducted to investigate the influence of Cu on intestinal and renal health in terms of oxidative stress in juvenile largemouth bass (2.69 ± 0.02 g). The results showed that Cu concentrations at and above 51.3 μg/L significantly increased the malondialdehyde contents (in the intestine) and simultaneously decreased total superoxide dismutase activity levels (in the intestine and kidney), glutathione peroxidase activity levels (in the kidney), and reduced glutathione contents (in the kidney), compared to control. In contrast to control, fish exposed to high Cu concentrations (at and above 1640 μg/L) demonstrated lower catalase activity levels in the intestine and kidney. Based on the findings in the study, waterborne Cu content for largemouth bass farming was recommended to be less than 51.3 μg/L.

Previous studies have shown that the critical swimming speed (Ucnt) of largemouth bass, Micropterus salmoides Lacépède, is significantly influenced by a number of factors including body mass (Beamish, 1970), training (Farlinger and Beamish, 1978), water temperature (Hocutt, 1973; Kolok, 1991) and photoperiod (Kolok, 1991). These studies share a common approach in that they were primarily concerned with comparing mean values of Ucrit of fish from different treatment groups, and individual variation within the groups was treated as statistical noise. While this approach is valid, it may overlook a significant source of performance variation - the variation found among individuals.Recent research (for a review, see Bennett, 1987) into the locomotor performance of amphibians and reptiles has suggested that individual variation is substantial and repeatable (i.e. performance variation of an individual forced to perform multiple times will be minor compared to the variation found when a number of individuals are forced to perform once). This research has been conducted on animals at a constant temperature, and also before and after an acute temperature change. No study has been done to determine whether performance repeatability is maintained following a chronic change in temperature. This may be particularly important with respect to fishes because many fish undergo physiological and morphological changes when subjected to chronic changes in water temperature. In the current study, variations in the Ucrit of individual bass were quantified, and performance repeatability was established at 11 and 22°C and after an acute and chronic decrease in water temperature from 20 to 10°C.Juvenile largemouth bass were obtained from the Wray Fish Hatchery, Colorado Division of Wildlife, during November and August. The fish used during November (N=7) varied from 7.8 to 9.8cm (mean 9.0cm) in fork length and from 6.2 to 12.2 g (mean 9.0 g) in body mass. The fish used during August (N=21) varied from 8.7 to 11.0 cm (mean 9.4 cm) in fork length and from 8.2 to 17.2 g (mean 11.4 g) in body mass. Correlations between Ucrit (when expressed in terms of body lengths per second, BLs−1) and fork length and body mass were not significant for the fish in either season.The bass were collected from holding ponds, then transported to Boulder where they were held at field water temperatures and photoperiods (November 11°C, 12h:12h light:dark; August 20-22°C, 14h:10h light:dark). All fish were fed commercial fish pellets ad libitum once per week, a feeding regime at which the fish maintained their body mass but did not grow. The fish were fasted for a minimum of 48 h before they were challenged with a bout of swimming.Ucnt was determined using the swim chamber previously described by Kolok (1991). Water continually circulated from a 2001 reservoir into a 2501 trough holding the submersed swim chamber. Water in the trough was chilled to the desired temperature using a chiller unit partially immersed in the reservoir. A 0.5 horsepower (373 W) water pump was used to generate water flow within the swim chamber. Water flows within the chamber were measured using an on-line pitottype flowmeter and the water flow was straightened using two flow straighteners located 20 and 40cm from the pump discharge region. The fish swam in a 7.7cm inner diameter 55 cm long clear acrylic tube attached downstream from the flow straighteners. Black plastic shaded the middle 35 cm portion of the swim chamber and fish generally remained in the shaded area until they were close to fatigue.The on-line flowmeter was calibrated using a Marsh-McBirney electronic flow meter and direct volume displacement. Water flow patterns within the chamber were analyzed using a 20 MHz pulsed Doppler system and a Doppler probe consisting of a 20 MHz ultrasonic crystal mounted in an 8 mm diameter plastic tube. Water flow was determined at 13 positions within the chamber at water velocities of 20 and 50 cm s−1, and was found to be essentially rectilinear at both velocities.Ucrit values were generated using a protocol modified from that of Kolok (1991). Individuals were placed into the swim chamber and given 1.5 h to habituate to a water velocity of 15cms−1. The 1.5 h habituation period was much shorter than the 24h period recommended by Beamish (1978). However, Kolok (1991) found that there were no significant differences between the performances of largemouth bass habituated to the chamber for 1.5 or 24 h at either 5 or 20°C. At the end of the habituation period, the fish were subjected to a swimming challenge in which water velocity was increased by 5 cm s−1 every 20 min until fatigue. The fish used in this study were approximately 10cm in fork length; therefore, the velocity increment used was approximately 0.5 BL s−1. A fish was assumed to be fatigued when it could no longer be encouraged, by gentle prodding, to swim off the flow straighteners at the rear of the chamber.For the repeatability tests at a constant temperature, seven fish during November (11°C) and nine fish during August (22°C) were challenged with two bouts of swimming. The fish were given at least 4 days post-capture to habituate to the laboratory environment before their first swimming challenge. Immediately following recovery from the first bout of swimming, each fish was weighed, measured for fork length and uniquely freeze-branded. The fish were then given 4 days to recover from the first swimming challenge (the fish were offered food on the second day after the challenge) before the performance challenge was repeated.The mean Ucrit of the fish swimming at 22°C was 3.81 BLs−1 during the first trial and 3.84 BLs−1 during the second. The mean Ucrit of the fish swimming at 11°C was 3.02 BLs−1 during the first trial and 3.01 BLs−1 during the second trial. These Ucrit values are consistent with previous findings on nonbranded juvenile large-mouth bass at similar temperatures; Farlinger and Beamish (1978) obtained a Ucrit of 3.41 BLs−1 at 25°C, while Kolok (1991) found it to be 3.60 BLs−1 at 22°C and 2.91 BLs−1 at 10°C.Variation in the individual values of Ucnt of fish at 11 and 22°C were substantial and repeatable. Ucrit values of individual fish from trial 1 varied from 2.56 to 3.44BLs−1 at 11°C, while at 22°C they varied from 3.17 to 4.03 BLs−1 (Fig. 1). This degree of variation was substantial enough that the best performers at 11°C had higher Ucnt values than the worst performer at 22°C. Correlations between the rank order performance of the fish in trial 1 and 2 were significant at 11°C (Spearman rank correlation coefficient, N=7, p=0.86, P=0.036) and 22°C (N=9, p=0.77, P=0.030), suggesting repeatability of performance. These results are consistent with the results from other ectothermic vertebrates, specifically lizards, snakes and toads (Bennett, 1987).For the repeatability tests in which water temperature varied, 12 fish were challenged with a bout of swimming at 20°C. Immediately following recovery from the first bout of swimming, each fish was weighed, measured for fork length and uniquely freeze-branded. Four days after the last fish had swum, the water temperature in the holding tanks was decreased to 10°C over 2 days. This rate of change was chosen because preliminary data suggested that a more rapid transfer would lead to significant mortality.The fish were then challenged with two bouts of swimming at 10°C, the first bout starting 48 h after the temperature drop and the second bout approximately 4 weeks after the drop in temperature. Because there was only one swim chamber available, there was a 48 h variation in the exposure time to the cold water between the first and last fish challenged with a bout of swimming. Variation in the amount of time the fish were subjected to cold water, however, was not significantly correlated with swimming performance in either the acute (N=12, r2=0.015, P=0.70) or chronic (N=12, r2 = 0.0002, P=0.96) challenge. At the end of the experiment, the fish were weighed and measured for fork length a second time. Neither body mass nor fork length changed significantly (t-test, P=0.7 and 0.9, respectively) during the 4 week acclimation period.There were significant differences (Kruskal Wallis, P<0.05) in the swimming performance of the fish acclimated to 20°C, 10°C (acute) and 10°C (chronic). The mean Ucrit of the fish decreased significantly (nonparametric multiple comparison, Zar, 1984) from 3.77 BL s−1 to 2.43 BL s−1 when they were exposed to a drop in water temperature from 20 to 10°C over 48 h. After 4 weeks at 10°C, the mean i/crit of these fish increased from 2.43 to 2.63 BLs−1, but this increase was not statistically significant. The performance of individual largemouth bass within the three treatment conditions was quite variable, with the difference between the best and worst performer being 0.97BLs−1 at 20°C, 1.48 BLs−1 at 10°C (acute) and 0.88BLs−1 at 10°C (chronic) (Fig. 2). When these performances were ranked, there was a significant correlation between the rank order performances of the fish in the three groups (Kendall correlation of concordance, N =12, W=0.75, P<0.025).Significant correlations between the rank order performance of a number of individuals before and after an acute temperature change have been shown for a number of lizard species (Bennett, 1980; Huey and Hertz, 1984), for yearling rainbow trout (J. E. Keen and A. P. Farrell, personal communication) and now for juvenile largemouth bass. These results suggest that in fish, as well as in other ectothermic vertebrates, individuals do not specialize at being good performers at either cold or warm temperatures. It appears, however, that the best performers remain so regardless of the temperature at which they perform.Fish acclimated to cold water frequently have elevated swimming performances compared to fish acutely exposed to the same water temperature (Roots and Prosser, 1962; Griffiths and Alderdice, 1972). Prior to the current study on largemouth bass, it was unknown whether an acclimatory response to cold water would significantly alter the rank order performance of the acclimated fish. This was not the case for the largemouth bass acclimated to 10°C for 4 weeks. While the rank order of one or two largemouth bass changed dramatically after the acclimation period, the significant correlation among the rank order performances of the fish at 20°C, 10°C (acute) and 10°C (chronic) was maintained (Fig. 2). This result suggests that the effect of acclimation to cold water was consistent from individual to individual, and that the best-performing fish would remain so even after acclimation to a different water temperature.The results of this study suggest that variation in the swimming performance of individual juvenile largemouth bass is substantial and repeatable for fish tested twice at one temperature, tested at different temperatures, or tested after a 4 week acclimation to a different temperature. These results strongly suggest that individual variation in Ucrit is more than statistical noise and that it is a source of variation that can be exploited when designing future experiments.All of the largemouth bass used in this study were graciously provided by the Colorado Division of Wildlife's Wray Hatchery.

This study aimed to explore the effects of dietary rapeseed meal replacing fish meal on growth performance, intestinal structure, gut microbiota, and related gene expression of juvenile largemouth bass (Micropterus salmoides). Five isonitrogenous and isolipidic diets were designed, in which rapeseed meal replaced 0% (FM, control), 5% (RM5), 10% (RM10), 15% (RM15), and 25% (RM25) of fish meal. Then, largemouth bass (11.00 ± 0.20 g) were randomly and equally allocated to 15 experimental tanks (25 fish per tank) for an 8-week feeding trial. The results showed that growth performance declined as replacement levels increased to 25%. However, the RM5 group had the highest body crude protein, distal intestinal muscle layer thickness (MLT), and plica height (PH) and width (PW), which were significantly higher than those of the FM group. In addition, compared to the FM group, the RM15 and/or RM25 groups had higher levels of D-lactic acid, diamine oxidase, and lipopolysaccharide. Furthermore, the RM25 group exhibited higher abundances of Lactococcus and Weissella but lower levels of Aeromonas and Staphylococcus compared to the FM group. Intestinal transcriptome analysis revealed that the PI3K-Akt and NF-κB signaling pathways were significantly up-regulated when comparing the RM25 and FM groups. The results demonstrate that the replacement of 5% fish meal with rapeseed meal did not have a negative impact on the physiological status of largemouth bass. However, a replacement level of 25% reduced growth performance and damaged intestinal structure, potentially by altering the abundance of intestinal microbiota and up-regulating the PI3K-Akt and NF-κB signaling pathways.

Inactivated lactobacillus plantarum promoted growth performance, intestine health and antioxidant capacity of juvenile largemouth bass, Micropterus salmoides

The study aimed to evaluate the effects of fermented tea residue (FT) on growth performance, intestinal morphology, liver antioxidant capacity and Aeromonas hydrophila infection in juvenile Largemouth bass. A total of 240 fish were randomly distributed in 12 tanks with 20 fish per tank (4 treatments with 3 replications) and fed with diets FT at the rate of 0 (control), 2, 4 and 6%. The weight gain rate (WGR), specific growth rate (SGR) and intestinal villi height (VH) of juvenile largemouth bass were significantly higher than those of the control group after feeding FT (P&amp;lt; 0.05); meanwhile, the liver superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and catalase (CAT) activities of juvenile largemouth bass were significantly higher and the malondialdehyde (MDA) levels were significantly lower than those of the control group after feeding FT (P&amp;lt; 0.05). Mortality occurred in all groups of largemouth bass after the injection of A.hydrophila, but feeding FT reduced the cumulative mortality compared with the control group (P&amp;lt; 0.05). In juvenile largemouth bass infected with A.hydrophila, the relative mRNA expression of the intestinal anti-inflammatory factors IL-10 and TGF-α was significantly higher and that of the pro-inflammatory factors IL-1, IL-15, IL-8, and TNF-α was significantly lower (P&amp;lt; 0.05). In summary, it can be seen that a 2% FT addition can improve the liver antioxidant capacity of juvenile largemouth bass, enhance the resistance to A.hydrophila and increase the growth of largemouth bass.