Weight Gain Rate Research Articles

Effects of a potential host gut-derived probiotic, Bacillus amyloliquefaciens AV5, on the growth, biochemical and metabolic responses, and disease resistance of Nile tilapia (Oreochromis niloticus)

The influence of the dietary probiotic Bacillus amyloliquefaciens AV5 on the growth, biochemical and metabolic responses, and disease resistance of Nile tilapia (Oreochromis niloticus) was evaluated. The commercial diet (GC), a diet containing 106 and 108 CFU/g of B. amyloliquefaciens AV5, denoted as G1 and G2, respectively, was fed for 30 days. Fish were allocated to 9 plastic tanks, and each diet was randomly assigned to triplicate groups of 40 fish (22.4 ± 1.3 g).After 30 days of the feeding trial, the specific growth rate, weight gain rate, and final weight increased significantly in G2 compared to those in GC and G1. Feed conversion ratio was significantly higher in the fish-fed GC group than in the G2 group. However, the survival rate of the fish ranged from 99.13 % to 97.17 %, with no significant difference. Glucose levels did not differ significantly (P < 0.05). Total antioxidant capacity (T-AOC), (superoxide dismutase (SOD), and catalase (CAT), as well as digestive enzymes (trypsin, lipase, and protease), were significantly increased in the G2 group relative to the GC and G1 groups.Significantly lower ALT, AST, CHO, TG, and MDA activities were observed in the G2 group than in the GC group. To evaluate the metabolomic response, PCA, OPLS-DA, and volcano plots revealed a distinct difference between the G2 and GC diets, suggesting that the G2 diet impacted the hepatopancreas of fish. Furthermore, challenge experiments revealed that fish fed B. amyloliquefaciens AV5 exhibited substantially increased resistance (P < 0.05) to S. agalactiae at a concentration of 1x108CFU/g. Therefore, dietary supplementation with B. amyloliquefaciens AV5 enhanced the growth performance, metabolic activity, and disease resistance of O. niloticus.

Quercetin supplementation improved the growth and health of juvenile Chinese mitten crabs (Eriocheir sinensis) fed low-fishmeal diets

The substitution of fishmeal with plant proteins can induce oxidative stress in aquatic animals and impair their growth and health. Quercetin is a potent natural antioxidant, but its specific effects on the growth and health of Chinese mitten crabs, as well as the underlying molecular mechanisms, remain unclear. This study aimed to investigate the impact of quercetin on the growth, physiological and biochemical parameters, gut microbiota, and transcriptome of juvenile Chinese mitten crabs (Eriocheir sinensis). Crabs (0.53 ± 0.01 g) were randomly divided into seven groups. One group was fed a diet containing normal fishmeal (35 % fishmeal), whereas the other six groups were fed diets containing low levels of fishmeal (15 % fishmeal) supplemented with different levels of quercetin (0, 250, 500, 1000, 2000, or 4000 mg/kg). Each group had four replicate tanks with 40 crabs per 300 L tank, and the experiment lasted for 56 days. The growth performance of the 35 % fishmeal group was significantly greater than that of the 15 % fishmeal group without quercetin. However, quercetin significantly increased the weight gain rate and specific growth rate of juvenile crabs, especially in the 1000 mg/kg quercetin group, where these rates exceeded those of the normal fishmeal group. The antioxidant capacity and immunity of the 35 % fishmeal group were significantly greater than those of the 15 % fishmeal group. However, quercetin supplementation promoted the antioxidant capacity and immunity of the crabs. Quercetin supplementation at 4000 mg/kg changed the gut microbiota structure by decreasing beneficial bacteria and increasing pathogenic bacteria. Quercetin supplementation enhanced the growth performance and antioxidant capacity of Chinese mitten crabs by increasing glutamate metabolism, pantothenic acid and Coenzyme A biosynthesis, sphingolipid metabolism, arachidonic acid metabolism, and cysteine and methionine metabolism. This study revealedthat dietary supplementation with quercetin can promote Chinese mitten crab growth, antioxidant capacity, and nonspecific immunity; improve gut morphology; and promote gut microbiota homeostasis. The optimal dietary concentration of 688–695 mg/kg is recommended on the basis of weight gain and specific growth rate analyses.

Ventral tegmental area amylin / calcitonin receptor signaling suppresses feeding and weight gain in female rats

The pancreatic peptide amylin promotes negative energy balance in part through activation of amylin receptors (AmyRs) expressed in the ventral tegmental area (VTA), but studies have been limited to male rodents. We evaluated whether VTA amylin signaling governs feeding and body weight in female rats. Indeed, pharmacological VTA AmyR activation suppressed chow intake and body weight in females. Viral-mediated knockdown of VTA calcitonin receptor (GPCR of AmyR) supports the physiological relevance of VTA amylin signaling for energy balance control in females. Collectively, these data support the relevance of VTA amylin signaling for energy balance control in both sexes.

Effect of Dietary Moldavian Balm (Dracocephalum moldavica L.) on Growth Performance, Antioxidant Status, Immune Response, and Gene Expression of Common Carp (Cyprinus carpio)

Abstract Chemical compounds used to prevent and control fish disease often cause environmental hazards; thus, alternative approaches as new and effective strategies are needed. The current investigation was performed with the aim of exploring the effects of dietary Moldavian balm (MB, Dracocephalum moldavica L.) on the growth, immune parameters, and antioxidant status of common carp (Cyprinus carpio). Fish (n=300, w=3.80±0.02 g) in four groups in triplicates were supplemented with 0%, 0.5%, 1%, and 2% MB. After 42 days, it was found that feed supplements increased final weight (FW), weight gain (WG), and specific growth rate (SGR) and decreased the food conversion ratio (FCR) (P&lt;0.05). In addition, fish supplemented with 2% MB significantly showed higher serum total protein (TP), alternative complement pathway (ACH50), and glutathione peroxidase (GPx) (P&lt;0.05). The 0.5% MB-supplemented fish represented higher levels of LYZ, alkaline phosphatase (ALP), total Ig, and ACH50 in their skin mucus in comparison with the unsupplemented fish (P&lt;0.05). The results also indicated that 2% MB resulted in a significantly higher expression level of intestinal tumor necrosis factor (TNF- α) (P&lt;0.05); however, the level of LYZ, interleukin-1β (IL-1 β), and TLRs decreased in supplemented fish. CAT and SOD expressions were increased in 0.5% MB supplement. In conclusion, MB could be recommended as an efficient feed additive to boost common carp’s growth, immunity, and health status.

Synergistic Benefits of Dietary Silymarin and Selenium on Growth, Immune Functions, Antioxidants, and Gut/Liver Health of Thinlip Mullet (Liza ramada) Juveniles

Abstract This study investigates the synergistic impact of silymarin (SI) levels combined with inorganic selenium (sodium selenite: Se) on growth, feed utilization, biochemical parameters, antioxidants, innate immunity, intestinal and liver histology, and gene expression of thinlip mullet (Liza ramada) juveniles. The experimental design involved thinlip mullets initially weighing 3.5±0.13 g, distributed in a completely randomized design with 30 fish per hapa (0.5 × 0.5 × 1 m), and conducted in triplicate over 60 days. Seven experimental diets were employed, including a control (without SI and Se supplementation), a negative control (with only Se supplementation), and four treatments with varying levels of silymarin (250, 450, 650, 850 mg/kg) alongside selenium (0.5 mg/kg diet). The growth performance results highlighted significant enhancements in final body weight, weight gain, and specific growth rate, particularly in the SI 850 mg/kg + Se treatment. Survival rates, feed intake, and feed conversion ratios showed positive trends across the SI-Se supplemented groups. Biochemical profiles of serum exhibited that the control diet induced elevated concentrations of glucose, cholesterol, alanine aminotransferase, aspartate aminotransferase, and urea, while Se or SI supplementation significantly mitigated these levels, with the lowest concentrations observed in the SI-Se supplemented groups. Moreover, SI supplementation increased serum protein content. Antioxidant enzyme activities, represented by superoxide dismutase (SOD), catalase (CAT), and catalase (GPx), demonstrated notable improvements in the SI-Se fortified groups, with significantly elevated GPx activity compared to the Se-supplemented and control groups. Immune system responses, including lysozyme, bactericidal, nitro-blue tetrazolium (NBT%), and serum alternative complement pathway (ACH50) activities, were highest in the SI-Se augmented groups. SI and Se in L. ramada reduce liver pro-inflammatory gene expression (IL-1 β, hepcidin) vs. control group. Histological examinations of the intestine and liver depicted structural enhancements, especially at moderate and high levels of SI with Se supplementation. The results indicate improved intestinal villi morphology and hepatic architecture, supporting the positive influence of dietary treatments on the health of thinlip mullet juveniles. In conclusion, the combined supplementation of SI at 850 mg/kg diet and Se at 0.5 mg/kg diet positively influenced the growth, biochemical profiles, antioxidant status, immune responses, gene expression, and histological integrity of thinlip mullet juveniles, providing valuable insights for optimizing aquafeed formulations.

Effects of straw structure and component on feeding efficiency of yellow mealworm for insect protein production

Elucidating the influence of straw structure and component on the feeding efficacy of yellow mealworm is pivotal for improving insect protein production from straw. This research utilized four distinct types of straws—water hyacinth straw (WHS), corn straw (CS), rape straw (RAS), and rice straw (RIS)—as the sole substrate for larvae. Results indicated that the straw utilization rate and fresh larval weight gain rate followed the order of WHS > CS > RAS > RIS. Analysis of straw structural characteristics demonstrated that decreasing straw hardness and cellulose crystallinity, while enhancing straw chewability, facilitated the ingestion of larvae. Feeding efficiency of yellow mealworm was positively correlated with the hemicellulose and crude protein content, and inversely correlated with lignin content in the straw. Additionally, the structural characteristics and components of straw significantly influenced the composition of the gut microbiota. These results offer valuable insights for optimizing yellow mealworm feeding on straw.

Growth performance of critically endangered Hypselobarbus pulchellus in biofloc system: Influence of carbon sources on immune response, enzyme and antioxidant activity

We investigated the effect of various carbon sources on the production performance of critically endangered Hypselobarbus pulchellus in biofloc system. The experimental setup comprised four biofloc treatment groups with various carbon sources (jaggery, tapioca, rice and corn flour) and a control group. Healthy early fry (0.0068 g) was randomly stocked at 100 individuals per m3 into 15 circular fibre reinforced plastic (FRP) tanks (1000 l) and raised for 90 days. All the tested carbon sources significantly influenced weight gain, weight gain (%) and specific growth rate (SGR), with the jaggery treatment displaying the best growth performance (p&lt;0.05). Fingerling survival rates varied from 93 to 95.67% (p&gt;0.05). Compared to the control, the biofloc groups had significantly lower concentrations of nitrogen compounds, specifically total ammonia nitrogen, nitrite and nitrate concentrations were significantly lowered (0.29, 0.35 and 1.32 mg l-1, respectively) in jaggery treatment (p&lt;0.05). In addition, the treatment using jaggery had a higher amount of plankton biomass and an abundance of the Bacillariophyceae group (80%). All biofloc groups displayed enhanced immune and antioxidant activity compared to the control. The jaggery treatment had elevated levels of lysozyme activity than other treatments (p&lt;0.05). Furthermore, fingerlings raised in BFT treatments had significantly higher amylase, protease and lipase activity (p&lt;0.05). Overall, this study’s findings suggest that the addition of various carbon sources significantly improves the production performance, with jaggery as the best carbon source for critically endangered H. pulchellus fingerling production in biofloc system to ensure sustainability. Keywords: Antioxidant activity, Fingerling, Heterotrophic bacteria, Jaggery, Specific growth rate, Sustainability

Nutrition, Growth, and Age at Puberty in Heifers

Puberty onset and age at first calving have a critical impact on livestock production for good reproductive efficiency of the herd and to reduce the duration of the non-productive stage of the growing heifer. Besides genetic factors, sexual maturation is also affected by environmental factors, such as nutrition, which can account for up to 20% of the observed variability. The rate of body weight gain during growth is considered the main variable influencing the age at puberty, dependent on planes of nutrition in growing animals during the prepubertal-to-pregnancy stage. This paper reviews current knowledge concerning nutrition management and attainment of puberty in heifers, considering the relevance of some indicators such as body measurements and hormones strictly linked to the growth and puberty process. Puberty onset is dependent on the acquisition of adequate subcutaneous adipose tissue mass, as it is the main source of the hormone leptin. Until a certain level, body condition score and age at puberty are negatively correlated, but beyond that, for fatter animals, such correlation is gradually lost. Age at puberty in heifers was reported to be negatively related to IGF-1. Future research should be planned considering the need to standardize the experimental animals and conditions.

Effects of Taurine and Vitamin C on the Improvement of Antioxidant Capacity, Immunity and Hypoxia Tolerance in Gibel Carp (Carrassius auratus gibeilo).

To investigate the effects of taurine and vitamin C on gibel carp (Carrassius auratus gibeilo), fish (41.85 ± 0.03 g) were fed three diets with 0% taurine + 0% vitamin C (D0), 0.1% taurine + 0% vitamin C (D1), and 0.1% taurine + 0.1% vitamin C (D2) for 8 weeks. Then 12-hour hypoxic stress test was conducted. The results showed that weight gain rate (WGR), specific growth rate (SGR), and sustained swimming time (SST) were significantly increased in the D2. CAT, SOD, T-AOC, and GSH were increased. GSH-Px and il-6 were decreased in D1 and D2. In hypoxia, CAT and T-AOC were decreased, while GSH, sod, and nrf2 were the highest in D1. Compared to normoxia, GSH-Px was increased, while SOD and MDA were decreased. Il-10 and nf-κb were increased. Vegf, epo, and ho-1 were increased and they all were higher than that in normoxia. The number of gill cell mitochondria and survival rate (SR) of gibel carp had an increasing trend but no significant difference among groups. In conclusion, taurine with vitamin C improved the growth and SST of gibel carp, and taurine and taurine with vitamin C improved antioxidant capacity, immunity, and hypoxia tolerance.

Protective Role of Sulforaphane against Physiological Toxicity of Triphenyltin in Common Carp (Cyprinus carpio haematopterus).

This experiment mainly explored the protective role of sulforaphane (SFN) against physiological toxicity of triphenyltin (TPT) in Cyprinus carpio haematopterus. In total, 320 Fish (56.90 ± 0.40 g) were randomly divided into four groups with four replicates each. The control group was fed the basal diet, the TPT group (TPT) was exposed to 10 ng L-1 TPT on the basis of the control group, the SFN + TPT group (TPT + SFN) was fed a diet supplemented with 10 mg kg-1 SFN on the TPT group, and the SFN group (SFN) was fed a diet supplemented with 10 mg kg-1 SFN. After 56 days of breeding trials, the results showed that TPT exposure resulted in a remarkable decrease (p < 0.05) in final weight, weight gain rate (WGR), specific growth rate (SGR), and condition factor (CF), but an increase (p < 0.05) in feed conversion ratio (FCR) and hepatosomatic index (HSI) of fish. TPT treatment decreased (p < 0.05) the amounts of hematocrit (Hct) and hemoglobin (Hb), plasma complement component 3 (C3) and C4 contents, alternative complement pathway (ACH50), acid phosphatase (ACP) and lysozyme (LZM) activities, liver glutathione (GSH) content, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPX) activities, interleukin 10 (IL-10), and SOD mRNA expressions, but increased (p < 0.05) plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, liver malonaldehyde (MDA) content, tumor Cyclooxygenase 2 (COX2), and necrosis factor α (TNFα), IL-1β, and MDA mRNA expressions. A histological analysis of the liver showed that a higher occurrence rates of the hepatocyte hypertrophy, nuclear disappearance and hepatocyte vacuolization was observed in the hepatocytes of fish exposed to TPT, and it was accompanied by the dilation of hepatic sinusoids. In addition, the toxicity induced by TPT was significantly improved in the groups that were treated with SFN, and SFN was able to improve growth performance and immunity, alleviate TPT-induced changes in inflammatory factors, ameliorate oxidative stress, and increase the activity of antioxidant enzymes (p < 0.05). The addition of SFN also alleviated liver damage caused by TPT and protected the structural integrity of the liver. Overall, these findings suggest that TPT inhibited the growth, immunity, and antioxidant capacity of Cyprinus carpio haematopteru. Dietary SFN could be beneficial for growth promotion, immunity, antioxidant capacity, and protection of liver structural integrity. Therefore, SFN is a prospective feed supplement for ameliorating the damage caused to fish by TPT contamination.

Rate of body weight gain during early gestation in F0 beef heifers has effects that extend multigenerationally to the F2 fetuses.

Our aim was to investigate the effects of maternal (F0) body weight (BW) gain during the first 84 d of gestation on body composition, ovarian reserve, and hormonal and metabolic parameters of breeding-age F1 heifers, as well as the body weight and morphometry of F2 fetuses. The study also evaluated the effect of maternal body weight gain (F0) on the mRNA relative abundance of the small intestine of both F1 heifers and F2 fetuses. Crossbred Angus heifers (F0; n = 100) were managed to gain 0.20kg/d (low gain [LG], n = 50) or 0.75kg/d (moderate gain [MG], n = 50) for the first 84 d of gestation. Subsequently, F0 dams were managed on a common forage-based diet for the rest of gestation until the weaning of the F1 offspring. At 15 months of age a subset of F1 heifers was randomly selected for the current experiment (n = 8 LG and n = 8 MG). Heifers were bred via artificial insemination (AI; d 0), then harvested on d 84 of gestation. On d -10, 42, and 84, BW was recorded, and blood was collected and analyzed for concentrations of glucose, non-esterified fatty acids, progesterone, insulin, and insulin-like growth factor-1. Weight of F1 carcasses, organs, gravid uteri, and F2 fetuses and organs were recorded at harvest. Visible follicles were counted on F1 ovaries at harvest, and histology was used to count microscopic follicles. Liver and jejunal samples from F1 heifers were collected to measure tissue oxygen consumption and jejunal samples from F1 heifers and F2 fetuses were collected for mRNA relative abundance analysis. Body weight of F1 heifers from MG dams tended to be 12kg greater (P = 0.06) than for F1 heifers from LG dams. Concentrations of glucose were greater (P = 0.03) in F1 heifers from the MG group, with no differences in other blood metabolites or follicular populations (P ≥ 0.16). Interestingly, mammary glands were heavier (P = 0.05) and placentas and body depth tended to be heavier and greater, respectively (P ≤ 0.10), for F2 fetuses from F0 LG heifers. Oxygen consumption in the liver and jejunum, as well as mRNA relative abundance in the jejunum of F1 heifers, were not affected by F0 rate of gain (P ≥ 0.16). However, the NDUFC1, SDHA, UQCR1, and PPARG genes were upregulated (P ≤ 0.05) in the jejunum of F2 fetuses from the LG group. In conclusion, BW gain of F0 heifers during early gestation exerts subtle effects on pre-breeding BW and blood metabolites in F1 offspring, with impacts present in F2 placenta, mammary gland, and intestine.

Effect of stocking density on growth performance, survival and production of Monosex Tilapia (Oreochromis niloticus) under nursery ponds in northern regions of Bangladesh

The present study was to assess and evaluate the culture potential of Tengra with short-cycle species in the seasonal water bodies of farmers’ fields and disseminate the cultural technologies in a different part of the country. The research study was evaluating the improvement of nursery management technique in drought prone area of Northern region in farmer field level. Before conducting research fish farmers of Different upazila were selected by departmental authority and pre training management. Growth, survival and production performances of Oreochromis niloticus fingerlings were evaluated for 40 days in nine nursery ponds having an area of 20 decimal each with an average depth of 1.0 m. Three stocking densities such as 1000 dec-1 (T1=Treatment-1), 1200 dec-1 (T2= Treatment-2) and 1400 dec-1 (T3=Treatment-3) were tested with three replications. Fry were fed with commercial nursery feed (30% crude protein). The rate of feeding was 25% to 8% of the estimated body weight of fry. The physico-chemical and biological parameters of pond water were within the suitable range for fish culture. Growth in terms of final weight, final length, weight gain, length gain and specific growth rate was significantly higher in T1 than those obtained from T2 and T3. The survival of fish fingerlings was higher in T1(85.67%) than T3 (76%) and T2 (83%) respectively. Maximum of fingerlings was produced in T2 than those in T1 and T3. Among the treatments evaluated, 1000 dec-1 was the best stocking density considering the growth performance of the fingerlings of monosex Tilapia, O. niloticus in nursery ponds.

Growth performance, antioxidant capacity, intestinal microbiota, and metabolomics analysis of Nile tilapia (Oreochromis niloticus) under carbonate alkalinity stress

To explore the effect of carbonate alkalinity stress on Nile tilapia (Oreochromis niloticus), fish were cultured at 3 alkalinity levels (0, 2 and 3 g/L NaHCO3) for six weeks. Survival, weight gain, and specific growth rate were measured. Liver samples were collected for measuring superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) content. Intestinal microbiota was analyzed using 16S rRNA gene sequencing, and metabolomic profiling identified differentially abundant metabolites. The results showed that the survival rate decreased in the fish exposed to 3 g/L NaHCO3, while weight gain and specific growth rate were not affected by the increased carbonate alkalinity. In the group exposed to 3 g/L NaHCO₃, activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total antioxidant capacity (T-AOC), and malondialdehyde (MDA) content in liver increased, while in 2 g/L NaHCO₃, only SOD and T-AOC activities rose compared to the control. Long-term carbonate alkalinity stress increased the abundance of Luteolibacter in intestine but decreased the abundance of Cetobacterium, Bacteroides, and Lactiplantibacillus. Metabolomics results showed that differentially abundant metabolites were highly enriched in pathways such as purine metabolism, vitamin B6 metabolism, lysine degradation, glycerophospholipid metabolism, and biosynthesis of cofactors in fish cultured at 3 g/L NaHCO3. These results suggested that carbonate alkalinity stress affects intestinal health by increasing the proportion of pathogenic bacteria and reducing beneficial bacteria. The correlation between N6,N6,N6-trimethyllysine, Ne,Ne-dimethyllysine, and Luteolibacter may represent an effective physiological adaptation and tissue repair pathway for Nile tilapia under carbonate alkalinity stress.

Dietary Chlorella vulgaris and Saccharomyces cerevisiae enhanced the growth performance, blood biomarkers, and antioxidative capacity of common carp (Cyprinus carpio)

Chlorella vulgaris (CV) has been investigated in aquaculture and shown as a potential functional feed additive. Therefore, this study tested the effects of dietary CV and Saccharomyces cerevisiae (SC) on the growth performance, blood biomarkers, and antioxidative capacity of common carp (Cyprinus carpio). Fish were allocated in four groups in triplicates, where each glass aquaria was stocked with 15 fish with 4.25±0.11 g/fish. Fish offered four test diets for 84 days: control (free from CV or/and SC), CV-supplemented diet (5 %), SC-supplemented diet (0.05 %; (10 × 109 CFU/g), and a mixture of CV and SC-supplemented diet (5 % CV+ 0.05 % SC), respectively. The results indicated that fish-fed CV or SC revealed enhanced growth performance (final weight, weight gain, and specific growth rate) and protein efficiency ratio, while the feed conversion ratio was reduced compared to the control. Fish-fed dietary SC or CV and SC mixture revealed higher villi length than the control. Besides, villi width and muscular thickness enhanced significantly in carps-fed CV and SC compared to the control. Fish-fed dietary CV and/or SC revealed lower moisture content and higher crude protein and total lipids than the control. The results indicated that fish-fed CV or SC revealed higher serum total protein than the control. On the other hand, the total cholesterol and triglyceride levels were markedly reduced in carps-fed dietary CV and/or SC compared to the control. The results indicated that fish-fed CV and/or SC revealed higher lysozyme activity, catalase, and glutathione peroxidase than the control. The superoxide dismutase of fish-fed CV or SC is higher than that of the control or CV and SC mixture. Additionally, the malondialdehyde levels (MDA) were markedly reduced in carp-fed dietary CV and/or SC compared to the control group. In conclusion, dietary C. vulgaris and/or S. cerevisiae can enhance growth performance and feed utilization in common carp. Besides, the biochemical blood markers and activated antioxidative capacity indicated that common carp fed C. vulgaris and/or S. cerevisiae revealed stable health status.

Effect of Dietary Copper on Growth Performance, Antioxidant Capacity, and Immunity in Juvenile Largemouth Bass (Micropterus salmoides)

This study evaluated the optimal dietary copper (Cu) levels and their effects on growth performance, body composition, and antioxidant capacity in juvenile largemouth bass (Micropterus salmoides). A total of 360 fish (initial average weight (1.67 ± 0.01 g) and initial average length (2.5 ± 0.2 cm)) were randomly assigned to 18 tanks, each containing 20 fish and six dietary Cu concentrations: 2.13 (control), 3.00, 3.66, 4.58, 4.64, and 5.72 mg/kg. The results indicated that fish receiving 3.00 mg/kg of Cu exhibited the best final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR), with a significantly reduced feed conversion ratio (FCR). While body composition (moisture, protein, lipid, and ash) remained consistent across groups, plasma total protein (TP) levels increased with Cu supplementation. Elevated triglycerides (TG) and albumin (ALB) were noted at 4.64 and 5.72 mg/kg, respectively, while glucose (GLU) levels decreased with an increase in dietary Cu. Antioxidant capacity, assessed via hepatic glutathione (GSH) and the activities of catalase (CAT), and showed significant improvements at 3.00 and 3.66 mg/kg Cu, while superoxide dismutase (SOD) showed the highest activity at a dietary Cu level of 5.72 mg/kg. Additionally, the expressions of tgf-β and tnf-α genes were significantly upregulated at a dietary Cu level of 5.72 mg/kg, while il-8 and il-10 genes were upregulated at dietary 3.66 mg/kg. The expression of nrf2 was significantly upregulated in response to a dietary Cu level of 3.66 mg/kg compared to the control group, and the expression of the keap1 gene was significantly upregulated in the fish fed with 5.72 mg/kg of dietary Cu. The results indicated that appropriate dietary supplementation could promote the growth performance and improve the antioxidant status the immunity of largemouth bass, and the optimal Cu requirement for FCR and SGR were approximately 3.10 mg/kg and 3.00 mg/kg, respectively.

A superior chitin product: Black soldier fly larvae chitin, beneficial to growth performance, muscle quality and health status of largemouth bass Micropterus salmoides, in comparison to shrimp chitin

We appraised the effects of black soldier fly larvae chitin (BSFC) with four levels (0.4 %, 0.8 %, 1.2 % and 1.6 %) and shrimp chitin (SC) with three levels (0.4 %, 0.8 % and 1.6 %) in diets on the growth performance, nutrient composition and health status of largemouth bass (8.00 ± 0.29 g) fed for 56 days. The results showed that the dietary 0.4 % BSFC distinctly increased the specific growth rate and weight gain rate of fish (P < 0.05), and evidently promoted the deposition of C22:1n-9, C24:1n-9 and increased total monounsaturated fatty acid content in the muscle (P < 0.05). BSFC and SC distinctly stimulated the secretion of β-N-acetylglucosaminidase in the hindgut (P < 0.05). The antioxidant status of fish was improved by BSFC and SC, which was attributed to the decreased malonaldehyde contents in the muscle and midgut and the increased total superoxide dismutase and catalase activities in the midgut. The 1.2 %–1.6 % BSFC and 0.8 %–1.6 % SC enhanced the non-specific immunity of fish, which was attributed to the marked promotion of lysozyme, acid phosphatase and alkaline phosphatase activities by BSFC and the distinct enhancement of lysozyme activity by SC in the serum or midgut (P < 0.05). BSFC and SC notably reduced the abundance of potential pathogenic bacterium Vibrio and Photobacterium (P < 0.05), and 0.4 %, 1.2 %, 1.6 % BSFC and 0.4 % SC markedly increased the abundance of probiotic bacterium Cetobacterium (P < 0.05), and the BSFC and SC of 0.8 % significantly increased the abundance of the probiotics Bifidobacterium and Bacillus respectively (P < 0.05). The increase of acetic acid, propionic acid, butyric acid and valeric acid concentrations in the hindgut might be related to the increase of intestinal probiotics, and 0.8 %–1.6 % BSFC and 0.4 % SC obviously increased the total short-chain fatty acid levels in the hindgut (P < 0.05). BSFC and SC remarkably reduced muscle fiber area and diameter (P < 0.05), while fiber densities were significantly increased under 0.4 %, 0.8 % BSFC and 0.4 % SC supplementation (P < 0.05), which was accordant with increased mRNA expression levels of myod, myf-5, smad-2, tgf-β1 and decreased mRNA expression levels of myos in the muscle. Collectively, BSFC and SC had no negative effect on the growth of largemouth bass, and improved the health status of fish. The dietary 0.4 % BSFC supplementation was beneficial to fish growth and muscle quality, and BSFC was a superior chitin product in comparison to SC.

Reoxygenation improves reduced hypothalamic leptin responsiveness induced by intermittent hypoxia in obese rats

To evaluate the effects of intermittent hypoxia-reoxygenation (IHR) on body weight, diet and water intake, circulating metabolites, and responses to central leptin injection in a rat model of diet-induced obesity (DIO). Rat models of DIO established by 12-week high-fat diet (HFD) feeding were randomized into normoxia group (n=15), intermittent hypoxia group (6% O2, 30 cycles/h, 8 h/day for 4 weeks; n=15), and IHR group (2 weeks of intermittent hypoxia followed by 2 weeks of reoxygenation; n=15). Body weight, diet and water intake of the rats were recorded, and circulating leptin, IL-6, and Ang-II levels were detected. After IHR treatment, the rats received intracerebroventricular injection of 4 μg leptin, and the hypothalamus and liver were taken 1 h later for detecting POMC, FRA-1 and FRA-2 expressions in the hypothalamus using immunohistochemistry, POMC, pSTAT3 and LepR expressions in the hypothalamus using Western blotting, and LepR mRNA expression in the hypothalamus and liver using RT-PCR. The rats in intermittent hypoxia group showed significantly increased weight gain, food intake and elevated systemic inflammatory cytokine levels. Intermittent hypoxia obviously inhibited the expression of POMC, lowered the expressions of FRA-1 and pSTAT3, reduced the responsiveness of the rats to exogenous leptin, and downregulated the mRNA and protein expression of LepR. Two weeks of reoxygenation treatment obviously reduced intermittent hypoxia-induced weight gain and metabolic disorder and improved leptin sensitivity of the rats. Prolonged intermittent hypoxia impairs hypothalamic leptin signaling by downregulating LepR expression to promote weight gain in obese rats, which can be improved by reoxygenation treatment.

Reducing the oxidation rate of Cr-coated Zr alloys under high temperature steam environment: An approach of an outer Zr coating

Cr-coated Zr alloys are widely regarded as promising accident-tolerant fuel (ATF) cladding materials. However, the rapid consumption of the Cr coating through both oxidation and diffusion demands a thick coating, which is detrimental to neutron economic. In this study, a thin Zr coating was fabricated on the top of the Cr coating to act as a protective layer, aiming to reduce the oxidation consumption rate of Cr coatings. In-situ weight gain measurements were performed to determine the oxidation kinetics. The microstructural evolution of the coating/substrate interface and the oxide/coating interface were analyzed. The results show that the weight gain rate of the Zr-Cr coated Zr alloy sample is lower than that of the bare Cr-coated Zr alloy samples. An equiaxed grain structure composed of Cr/Zr mixed oxides was observed in the coating, which helps to inhibit elements diffusion and reduce the oxidation rate of Cr coatings. After steam oxidation at 1000 °C for 4 h, the sample structure consisted of the Zr substrate, a Cr2Zr layer, a residual Cr coating, a Cr2O3 layer, a Cr/Zr mixed oxides layer, and a ZrO2 layer.

Beneficial effects of Haematococcus pluvialis on growth and hepatopancreas health status in crayfish (Procambarus clarkii) via remodeling the gut microbial metabolic functions

Plant proteins fulfill roles in low-fishmeal diets for crustaceans, but their overuse could have negative effects. Haematococcus pluvialis has the potential to be used as a functional additive due to its high astaxanthin. As such, this study aimed to investigate the effects of dietary H. pluvialis supplementation on growth, hepatopancreas health, and gut metabolic functions in crayfish. 720 crayfish with average weight around 9.20 g were randomized into six treatments (HP0, HP0.3, HP0.6, HP0.9, HP1.2, and HP1.5) in three replications each, and fed six different dosages of H. pluvialis over sixty days. Crayfish exposed to H. pluvialis at concentrations of 0.3, 0.6, and 0.9 % showed significant increases in final average weight, weight gain rate, and specific growth rate (P < 0.05) compared to the HP0 group, together with the highest contents of muscle and shell astaxanthin in the HP0.9 group. Furthermore, increasing H. pluvialis supplementation exhibited the potential to repair hepatopancreas, as demonstrated by the decrease in hemolymph malondialdehyde (MDA) content and activities of alanine aminotransferase and aspartate aminotransferase, as well as the increase in the total protein content, superoxide dismutase, and glutathione peroxidase (GSH-Px) activities. Moreover, high H. pluvialis diets improved microbial dysbiosis by increasing specific microbes, the alpha diversity index, and shifting prominent phyla such as Proteobacteria and Firmicutes. Specifically, dietary H. pluvialis inclusion significantly decreased Vibrio (Proteobacteria) compared to the HP0 group (P < 0.05), but Tyzzerella (Firmicutes) showed the opposite regulatory pattern. A further statistical check revealed that 20 differential OTUs were shared by all H. pluvialis groups compared to the HP0 group, with OTU1439 and OTU2941 identified as the main growth-liver health contributors. Accordingly, high H. pluvialis diets contributed to more complex and stable microbial networks, and down-regulated alanine, aspartate, and glutamate metabolism, as well as lipopolysaccharide biosynthesis. Taken above, the optimal dietary H. pluvialis inclusion level was recommended to be 0.78–0.86 % according to the growth and astaxanthin contents. High H. pluvialis feeding reversed gut microbial dysfunction and improved hepatopancreas antioxidant capacity.

Sympathetic innervation of interscapular brown adipose tissue is not a predominant mediator of OT-elicited reductions of body weight gain and adiposity in male diet-induced obese rats.

Recent studies indicate that central administration of oxytocin (OT) reduces body weight (BW) in high fat diet-induced obese (DIO) rodents by reducing energy intake and increasing energy expenditure (EE). Previous studies in our lab have shown that administration of OT into the fourth ventricle (4V; hindbrain) elicits weight loss and stimulates interscapular brown adipose tissue temperature (TIBAT) in DIO rats. We hypothesized that OT-elicited stimulation of sympathetic nervous system (SNS) activation of IBAT contributes to its ability to activate BAT and reduce BW in DIO rats. To test this, we determined the effect of disrupting SNS activation of IBAT on OT-elicited stimulation of TIBAT and reduction of BW in DIO rats. We first confirmed that bilateral surgical SNS denervation to IBAT was successful based on having achieved ≥ 60% reduction in IBAT norepinephrine (NE) content from DIO rats. NE content was selectively reduced in IBAT by 94.7 ± 2.7, 96.8 ± 1.8 and 85.9 ± 6.1% (P<0.05) at 1, 6 and 7-weeks post-denervation, respectively, and was unchanged in liver or inguinal white adipose tissue. We then measured the impact of bilateral surgical SNS denervation to IBAT on the ability of acute 4V OT (1, 5 μg) to stimulate TIBAT in DIO rats. We found that the high dose of 4V OT (5 μg) stimulated TIBAT similarly between sham and denervated rats (P=NS) and that the effects of 4V OT to stimulate TIBAT did not require beta-3 adrenergic receptor signaling. We subsequently measured the effect of bilateral surgical denervation of IBAT on the effect of chronic 4V OT (16 nmol/day) or vehicle infusion to reduce BW, adiposity and energy intake in DIO rats. Chronic 4V OT reduced BW gain by -7.2 ± 9.6 g and -14.1 ± 8.8 g in sham and denervated rats (P<0.05 vs vehicle treatment), respectively, and this effect was similar between groups (P=NS). These effects were associated with reductions in adiposity and energy intake (P<0.05). Collectively, these findings support the hypothesis that sympathetic innervation of IBAT is not required for central OT to increase BAT thermogenesis and reduce BW gain and adiposity in male DIO rats.