Effects of Microbial Biomass and Mineral Premixes on Growth Performance and Nutrient Utilisation in Penaeus monodon Fed Low Fishmeal Diets

This study aimed to investigate the growth performance, feed utilization and innate immune response of snakehead fish (Channa striata) that had received a low fish meal-based diet and supplementation with protein hydrolysate. A fish meal-based diet was consider as a ‘high fish meal diet’ in feed formular (HF) and a ‘low fish meal diet’ (LF) replaced 40% of fish meal with soybean meal. Two other diets were prepared by supplementing tuna hydrolysate (TH) and poultry hydrolysate (PH) in LF diet. The experimental fish (initial mean weight 4.1 ± 0.15 g) were randomly assigned to quadruplicate group and fish were randomly distributed into 500-L circular plastic tanks at a density of 70 fish per tank. Each experimental diet was handfed three times daily to apparent satiation for eight weeks. At the terminal period, the results showed no significant difference in fish survival rates among all groups (p > 0.05), and significant improvements (p < 0.05) in percentage of weight gain and specific growth rate were obtained in fish fed dietary TH compared to among all group. In terms of feed utilization, the data showed that there was also no significant difference (p > 0.05) in feed conversion ratio (FCR) and protein efficiency ratio (PER) among all groups. Values of hematological parameters did not significantly differ among experimental groups (p > 0.05). Serum lysozyme levels increased significantly in fish fed diet TH. Other immune parameters (Catalase, MPO, SOD and RBA) were not altered by diet. However, fish fed diet TH and HF had strong fluorescence intensity, indicating slightly higher respiratory burst activity than other groups. Overall, the present findings suggest that supplementing 2.5% tuna hydrolysate in the low fish meal-based diet can improve feed intake, growth performance and innate immunity in snakehead fish.

This study was conducted to evaluate the application of four fish origin probiotics to relieve the side effects induced by SBM in shrimp. Shrimps were fed with high fish meal diet (C0, positive control containing 500 g/kg FM and 0 g/kg SBM), low fish meal diet (C, control containing 250 g/kg FM and 340 g/kg SBM) or the control diet (C) supplemented, respectively, with 1.0 × 108 CFU/g Bacillus pumilus SE5 (T1), Psychrobacter sp. SE6 (T2), Enterococcus faecium MM4 (T3) or Bacillus claussi DE5 (T4). After 6 weeks of feeding, the growth performance, hepatopancreatic digestive enzymes, intestinal histological structure and immune parameters were determined. The results showed that compared with high FM group (C0), significantly lower WGR and SGR as well as higher FCR were observed in the low FM group (C) (p < .05). Compared with the control, significantly lower FCR was observed in treatment T1 (p < .05), but not in treatments T2–T4. Protease, amylase and lipase activities in all the treatments (T1-T4) were significantly higher than the control (p < .05). GOT and GPT activities in the control were significantly lower than the C0 (p < .05), while higher MDA level was recorded in the control (p < .05). Meanwhile, higher GPT activities were observed in treatments T1-T4 compared with the control (p < .05). Compared with the C0, lower SOD, ACP and AKP activities were observed in the control. Significantly improved SOD and AKP activities were observed in all probiotic feeding groups compared with the control (p < .05). The control diet led to significant reduction of intestinal wall thickness and villus height compared with the C0 (p < .05), while significantly higher intestinal wall thickness and villus height were exhibited in all the probiotic groups compared with the control (p < .05), except intestinal wall thickness in treatment T3. Thus, these results demonstrated that the four fish origin probiotic strains could relieve the side effects induced by high level of SBM in shrimp, while probiotic B. pumilus SE5 showed the best performance.

Excessive enterocyte lipid accumulation, with the suggested term lipid malabsorption syndrome (LMS), is frequently observed in Atlantic salmon (Salmo salar L), in small fish in fresh water as well as in large fish in seawater. The symptoms indicate insufficient supply of components involved in lipid assimilation. The questions addressed in the present work were whether dietary supply of components involved in phospholipid and sterol metabolism might prevent LMS. Atlantic salmon (35 fish, 330 g per 600 L tank) were fed a low fish meal diet (LF) as such or supplemented with taurocholate at two levels (3.5 and 6.9 g/kg), cholesterol (2.0 g/kg), taurine (0.8 g/kg), phosphatidylcholine (15.1 g/kg), choline (3.7 g/kg), cysteine (0.8 g/kg) or methionine (1.0 g/kg). A high fish meal diet (HF) was also included. The overall growth rate of the fish was high (TGC>4.2) with no significant effects of diet. Fish fed the LF diet showed increased relative weight of the pyloric and mid intestine and excessive lipid accumulation in the enterocytes, characteristics which were nearly absent in fish fed the HF diet and the LF diet supplemented with choline and phosphatidylcholine. The phosphatidylcholine supplemented diet showed significantly higher lipid digestibility than the LF diet. None of the other supplements eliminated the signs of excessive enterocyte lipid accumulation. Phosphatidylcholine down-regulated pcyt1a, involved in the phosphatidylcholine synthesis, and both choline and phosphatidylcholine induced apoaIV, important in lipoprotein assembly, and markedly suppressed the lipid droplet marker plin2. Methionine supplementation did not stimulate endogenous synthesis of choline. Cholesterol supplementation suppressed sterol uptake and de novo cholesterol synthesis, and induced sterol efflux from the intestinal mucosa. Taurocholate and taurine induced their respective metabolic pathways. All feed supplements, in particular cholesterol and cysteine, down-regulated genes related to antiviral, chemokine, antigen presentation, immunoglobulinfunctions, as well as of extracellular proteases. The results of this study confirm the results from our previous study showing that choline or phosphatidylcholine is a necessary ingredient in low fish meal diets.

Plant‐derived products have been suggested to partially replace fishmeal in aquafeed; however, often at decreased growth performance, inflammatory responses, and increased susceptibility to diseases. This study assessed the effects of the commercial phytogenic feed additive Digestarom PEP MGE on the growth, nutritional performance, and immune response of L. vannamei. Juvenile shrimp (N = 540) were stocked in 36 tanks (V = 100 L) for 63 days and fed one of the four experimental diets: (i) standard formulation (control, 24% fishmeal), (ii) low fishmeal diet (5%), (iii) low fishmeal diet plus 0.2 g/kg Digestarom PEP MGE, and (iv) low fishmeal diet plus 0.4 g/kg Digestarom PEP MGE. The results obtained after 63 days of feed supplementation suggest that the blend of essential oils tested compensated for the negative performance and health consequences of the low fishmeal diet. Particularly, the survival, FCR, total hemocyte count, and respiratory burst of the shrimp fed a low fishmeal diet supplemented with this phytogenic improved up to the levels recorded for shrimp fed a high fishmeal diet. Overall, results suggest that Digestarom PEP MGE can be incorporated into shrimp low fishmeal diets to compensate for the negative performance and immunological effects of partially replacing fishmeal with plant‐based protein.

Manipulation effects of jack mackerel meal (JMM) in the low fish meal (FM) diets substituting 50% FM with meat meal (MM) on growth performance of olive flounder and economic analysis were determined. Seven experimental diets were created. The control (Con) diet contained 60% FM. In the other diets, 50% of the FM level used for the Con diet was substituted with MM, and then graded levels (0, 10, 20, 30, 40, and 50%) of JMM were included at the expense of FM, named the MJ0, MJ10, MJ20, MJ30, MJ40, and MJ50 diets, respectively. The experimental diets were distributed to triplicate groups of fish. A total of 525 fish was divided into 21 flow‐through tanks. Fish were hand‐fed to apparent satiation for 8 weeks. Weight gain, specific growth rate (SGR), and feed consumption of fish fed the Con diet were comparable with fish fed the MJ20, MJ30, MJ40, and MJ50 diets. Weight gain, SGR, and feed consumption of fish linearly improved with JMM inclusion levels in the low FM diets replacing 50% FM with MM. The strong correlation between isoleucine and lysine content among essential amino acids in the experimental diets versus weight gain, SGR, and feed consumption of olive flounder were observed. Dietary treatments did not influence feed utilization, chemical composition, and amino acid profiles of fish. Incorporated 20%–50% JMM as an effective feed attractant and enhancer in the low FM diets replacing 50% FM with MM achieved comparable weight gain, SGR, and feed consumption to fish fed a 60% FM‐based diet. Finally, the MJ50 diet led to the highest economic profit index (EPI) for farmers.

SUMMARY: The present study was carried out to reduce the total phosphorus loading (T-P) from carp by replacing dietary fish meal with alternate proteins (blood meal and defatted soybean meal). The experimental diets were formulated according to the Lake Kasumigaura Standard (crude protein 3.5 kcal/g) and contained fish meal at the levels of 10, 15, 20, 25, and 30%. The dietary total phosphorus (P) contents were between 0.9 and 1.4%, and water extractable P (available P for carp) ranged from 0.55 to 0.70%. Duplicate groups (n = 50) of carp (average weight 2.2 ± 0.3 g) were fed one of the five experimental diets to satiation, three times a day for 12 weeks, at 20.0 ± 1.6°C. T-P from each group was determined based on water extractable P and the rate of P absorbed and retained in carp. The growth performance was highest in fish fed the diet containing 25% fish meal followed by 30%, although there was no marked difference between the treatments except for the 10% fish meal group. The feed gain ratio ranged between 0.96 and 1.14. The values for T-P (kg/t carp production) were effectively reduced by decreasing dietary fish meal levels, and ranged from 5.9 for the 10% fish meal diet to 9.6 for the 30% fish meal diet. However, low fish meal diets with high amounts of alternative proteins resulted in high nitrogen loading, therefore, a suitable level of fish meal in carp diet was estimated to be 20–25%, under the present feeding conditions, substituted by a combination of blood meal and defatted soybean meal.

Effects of calcium carbonate inclusion in low fishmeal diets on growth, gastrointestinal pH, digestive enzyme activity and gut bacterial community of European sea bass (Dicentrarchus labrax L.) juveniles

The effect of a digestibility enhancer (DE) in a low fish meal diet on the growth and health status of the Pacific whiteleg shrimp, Penaeus vannamei was investigated using seven iso-nitrogenous and iso-lipidic (35% protein and 6% lipid) diets. These seven experimental diets were fed to P. vannamei, divided into five replicate experimental groups of shrimps assigned per dietary treatment, for 90 days. The feed conversion ratio (FCR) showed significant differences () with the diet of 6% palm kernel meal (PKM) + DE delivering the best feed efficiency. Meanwhile, there were no significant differences in the survival rate (SR) found, however, numerically the group of shrimps fed with 2.5% PKM with DE had a higher SR compared to the other dietary treatments. For growth performance, no significant differences in the growth performance of the shrimp among the dietary treatments were observed, including also the date for the final body weight and the percentage weight gain. The body composition of the shrimp showed slight changes in nutrient retention, where those shrimp fed the diet with DE supplementation had a marginal increase in protein content (21.33% compared to 20.53% in the control) and energy content (96.46 kcal/100 g with 9% PKM + DE, versus 89.79 kcal/100 g in the control). In terms of health criteria, P. vannamei appeared to show changes in their status for specific indicators. This was apparent for shrimp fed increasing PKM irrespective of the additive for the total haemocyte counts. There was a progressive reduction in the level of lysozyme in shrimp fed PKM and this effect was accentuated for the PKM treatment receiving DE. The inclusion level of DE as much as 0.2% in feed formulated with graded inclusion levels of PKM, up to 9% to partially reduce the inclusion of fish meal and soybean meal, is still able to maintain the optimal growth and health of the shrimp, at the same time, we noted an increase in production efficiency by reducing feed formulation costs by 1.23-3.87%.

This experiment aimed to evaluate the impact of dietary hydroxyproline (Hyp) supplementation on the muscle quality of juvenile Pacific white shrimp (Litopenaeus vannamei) fed a low fishmeal diet. Six formulated diets included one high fishmeal (HF; 25% fishmeal content) and five low fishmeal diets (10% fishmeal content) with 0%, 0.2%, 0.4%, 0.6% and 0.8% Hyp (LF0, LF2, LF4, LF6 and LF8, respectively). Each diet was assigned to four replicates, and 40 shrimp (0.32 ± 0.00 g) per replicate were fed four times a day for 8 weeks. Dietary Hyp supplementation had little effects on growth performance, but increased the contents of Hyp, prolyl 4-hydroxylases (P4Hs), and collagen. The meat yield, springiness, hardness, chewiness, and cohesiveness of muscle were the highest in the LF4 group among the low fishmeal groups (P < 0.05). Cooking loss and freezing loss of muscle were the lowest in the LF4 group (P < 0.05). Dietary supplementation with 0.4% Hyp increased the myofiber density and decreased the myofiber diameter of muscle (P < 0.05). Supplementation of Hyp in the diet up-regulated the mRNA expression of smyhc5, smyhc15, col1a1, col1a2, igf-1f, tgf-β and tor and down-regulated the mRNA expression of smyhc1, smyhc2, smyhc6a (P < 0.05). Supplementation of Hyp in the diet up-regulated the protein expression of P-4E-BP1, P-AKT, AKT and P-AKT/AKT (P < 0.05). These results suggested that the addition of 0.4% Hyp to low fishmeal diets improved the muscle quality of L. vannamei.

Reducing aquaculture’s reliance on wild fish remains a major challenge. Protein hydrolysates, often derived from food by-products, offer a promising, sustainable, and functional alternative to marine proteins. This study evaluated their use as a palatability enhancer (PE) by top-coating feeds with a low-dose liquid hydrolysate, primarily from shrimp, to reduce fish meal (FM) in juvenile red seabream ( Pagrus major ) diets. Experimental feeds included a high FM diet (HFM, 30 % FM), a low FM diet (LFM, 15 % FM) and two additional diets with 2 % PE top-coated (HFM+PE and LFM+PE). Six replicate tanks, each with 40 fish, were fed one of the diets twice daily to satiety for 15 weeks. Half the tanks experienced intermittent stress (1-min net chasing for one week, every 3 weeks). After the trial, fish were challenged with Edwardsiella tarda . Both basal diets resulted in comparable growth and feed efficiency. Reducing fish meal from 30 % to 15 % in the LFM diet resulted in a baseline reduction of approximately 25 % in wild fish use, as estimated by the economic Fish-In: Fish-Out (eFIFO) ratio. PE supplementation further improved growth (+5.6 % for SGR), health, and feed utilization (-7.5 % for FCR), enabling an additional 6 % reduction in wild-caught fish input compared to the LFM diet alone. The beneficial effects of PE were consistent despite intermittent stress, and survival following bacterial challenge was significantly higher with PE supplementation. In conclusion, liquid hydrolysate used as a PE provides a cost-effective way to reduce pressure on wild fish stocks while maintaining high feed performance. • Liquid shrimp hydrolysate top-coated on low fish meal diet as palatability enhancer. • Hydrolysate increased feed intake and growth by ∼6 % under repeated stress. • Hydrolysate mitigated negative effects of low fish meal diets on performance. • Hydrolysate maintained fish health and resistance to disease. • Hydrolysate supported 50 % fishmeal replacement and reduced eFIFO by 31 %.

Tea tree oil (TTO) is an essential plant oil with diverse antibacterial and antioxidant properties; however, whether the role played by TTO in low fish meal (LF) diets induced the observed effects in the farmed crustaceans remains unclear. Therefore, this study used Macrobrachium rosenbergii as the model crustacean, and an 8-week feeding experiment with NF (normal fish meal), LF (soybean meal replacing 40% fish meal), and LFT (LF with 200 mg/kg TTO) diets was conducted to evaluate the positive effects of TTO under the LF diet. Compared to the NF diet, the LF diet reduced hemolymph antioxidant capacity and non-specific immunity, and induced hepatopancreas apoptosis and damage. However, in comparison with LF, LTF significantly ameliorated morphological impairment in the hepatopancreas, improved hepatopancreas energy metabolism by upregulating the Bcl-2/Bax and Akt/mTOR pathways, and enhanced antioxidant and non-specific immune capacity by activating the NF-κB/NO pathway. In addition, LFT repaired intestinal barrier injury and the imbalance of intestinal microbiota induced by the LF diet. Moreover, the Pearson correlation revealed the variations of the above indicators, which were related to the abundance changes of Klebsiella, Clostridium sensu stricto 12, Thermobifida, Bifidobacterium, and Alistipes, indicating that these microbes might serve as prospective targets for the intestine–hepatopancreas axis to affect hepatopancreas apoptosis, metabolism, and non-specific immunity. In summary, 200 mg/kg TTO supplementation mediated gut microbiota and positively improved energy metabolism and non-specific immunity, thereby alleviating hepatopancreas dysplasia and damage induced by the LF diet in M. rosenbergii.

Objective: This study assessed the potential of three widely-available local oilseed byproducts, soybean (SBM), copra (CM) and palm kernel meals (PKM) as partial replacements of fishmeal in Nile tilapia (O. niloticus) diets in terms of their digestibility and effects on growth and nutrient utilization. Methods: Apparent digestibility coefficients (ADCs) were determined using chromic oxide as an inert marker in test diets formulated to contain 30% of each of the test ingredients by weight and 70% of a fishmeal-based reference diet. The 8-week growth trial evaluated the effects of partial replacements of fishmeal by the oilseed byproducts at different dietary inclusions. The soybean meal diets were formulated with the soybean meal contributing 25% (SBM25) and 50% (SBM50) of total dietary protein. Copra and palm kernel meals each contributed 10 (CM10 and PKM10) and 20% (CM20 and PKM20) of total dietary protein in their respective diets. The test diets were compared to a control diet with fishmeal as the sole protein source. Results: Nutrient digestibilities of the test ingredients were generally significantly higher for the soybean meal than the copra and palm kernel meals. The ADCs of the soybean, copra and palm kernel meals were; protein, 90.57%, 69.36% and 61.12; lipid, 96.14%, 95.64% and 95.85%; fibre, 96.74%, 77.61% and 55.07% and energy, 91.99%, 73.61% and 75.14% respectively. All the dietary treatment groups recorded significant growth at the end of the trials with the fish in the control and SBM25 groups more than tripling their respective mean initial weights. All the other treatment groups more than doubled their mean initial body weights. Daily growth rates ranged from 1.40% day-1 for the PKM20 group to 2.26% day-1 for the control group. Conclusion: The study has shown that the test ingredients can partially replace fishmeal in Nile tilapia diets without considerably compromising diet digestibility and carcass traits although higher dietary levels of the oilseed byproducts negatively affects growth.

Optimizing valine supplementation in low-fish meal diets for enhanced growth, digestion, antioxidant capacity, and intestinal health of triploid rainbow trout (Oncorhynchus mykiss)

This study assessed genetic parameters including genotype by diet interactions in growth and survival of Pacific white shrimp (Litopenaeus vannamei) fed with a low-protein and low-fishmeal diet (protein: 35%, fishmeal: 9%) and a general commercial diet (protein: 42%, fishmeal: 25%). A total of 2774 shrimp from 38 families were divided into two groups for a feeding trial, an experimental group fed with the low-protein and low-fishmeal diet and a control one fed with the commercial diet. A 7.06% increase in BW of shrimp fed the control diet over the experimental diet, and no significant difference in survival rate between the diets was observed after 75 days of trial. There was no significant difference between heritability estimate of BW on the experimental diet (0.671 ± 0.119) and that on the control diet (0.585 ± 0.108; p > 0.05), and heritability estimate of survival on the experimental diet (0.199 ± 0.047) was significantly higher than that on the control diet (0.050 ± 0.019; p < 0.01). Genetic correlation between BW recorded on the two diets was very high (0.928 ± 0.042), indicating an insignificant genotype by diet interaction effect for this trait. Relatively, genetic correlation for survival was low (0.251 ± 0.160), indicative of genotype by diet interaction effect. Our results indicate that 35% protein and 9% fishmeal in diets with high level of plant-based protein are feasible in inducing acceptable growth and survival of L. vannamei. This study confirms that the current low-protein and low-fishmeal diet is an appropriate environment for evaluating and selecting genotypes for improved growth of L. vannamei.

Effects of dietary chenodeoxycholic acid supplementation in a low fishmeal diet on growth performance, lipid metabolism, autophagy and intestinal health of Pacific white shrimp, Litopenaeus vannamei