Feed Utilization Research Articles

Improving mannanase production in Bacillus subtilis for fibre hydrolysis during solid-state fermentation of palm kernel meal

The primary challenge in utilizing palm kernel meal (PKM, an agricultural by-product) as non-ruminant livestock feed is its high fibre content, predominantly in the form of mannan. Microbial fermentation offers an economically favourable alternative to enzyme supplementation for breaking down fibre in lignocellulosic biomass. In a recent study, our group isolated a B. subtilis strain F6 with a fast response time for mannanase production upon exposure to PKM. This work focuses on improving the mannanase production of the B. subtilis strain to achieve greater fibre hydrolysis of PKM without extending fermentation time. Mannanase GmuG, sourced from B. subtilis F6 and verified for its hydrolytic activity on PKM fibre, was homologously expressed using a replicative plasmid (pBE-S). Enzyme production was systematically improved by optimizing various regulatory elements, including the promoter, ribosome binding site, and signal peptide. Consequently, the neutral detergent fibre content of PKM was substantially reduced by 36.4 % in 22 h of solid-state fermentation using the engineered strain. Lastly, the highest mannanase-producing strain was examined for scaled-up fermentation. The impacts of fermentation on fibre and protein contents, as well as the surface morphology of PKM, were analysed. The outcomes of this study offer an efficient method for robust mannanase expression in B. subtilis and its potential application in the biotransformation of PKM and other mannan-rich bioresources for improved feed utilization.

Effects of Dietary Lipid Levels on the Growth, Muscle Fatty Acid and Amino Acid Composition, Antioxidant Capacity, and Lipid Deposition in Mirror Carp (Cyprinus carpio).

In fish, increasing the crude lipid level of feed can save protein and improve feed utilization. Mirror carp (Cyprinus carpio) is one of the most widely farmed fish species in the world. In this study, mirror carp larvae were fed isonitrogenous diets with different lipid levels (3%, 5%, 7%, 9%, 11%, and 13%). The rearing trial lasted for eight weeks. The results revealed that when the fat content was 9%, the AWGR, WGR, and FCR were highest, whereas FCR was lowest. The AWGR was correlated with the dietary lipid level, and the regression equation was y = -2.312x2 + 45.01x + 214.49. Compared with those in the control group, the T-CHO and TG contents were significantly greater in the 13% lipid content groups and significantly lower in the 9% lipid content groups (p < 0.05). In terms of muscle quality, the contents of MUFAs, PUFAs, and DHA + EPA were significantly greater than those in the other experimental groups (p < 0.05). Oil red O staining revealed a lipid content of 13% with severe fat deposition. In addition, the results of the analysis of antioxidant enzyme activity revealed that the activities of GSH, CAT and T-AOC were significantly greater at the 9% lipid content, and that the MDA content was significantly greater at the 13% lipid content (p < 0.05). Similarly, the mRNA levels of GH, IGF-I, FAS, and LPL were significantly highest at a lipid level of 9% (p < 0.05). The above results revealed that the optimal dietary lipid requirement for the fast growth of mirror carp (6.86 ± 0.95 g) was 9.74% on the basis of nonlinear regression analysis of the AWGR. The dietary lipid level (9%) improved the growth, stress resistance, and lipid utilization of mirror carp to a certain extent.

Performance, Feeding Behavior, and Nutrient Utilization of Different Goat Breeds Fed Creep Feed

Introduction: Feed is one of the main factors to improve animal production. The utilization of feed is depended on quality, quantity, type, breed, and rate of passage of feed. This study aimed to evaluate the performance, feeding behavior, and nutrient utilization of growing Etawah crossbred and Senduro goats fed different forms of starter concentrate of creep feed. Materials and methods: Twelve local growing goats were used in this study, consist of six Etawah crossbred and six Senduro goats with average body weight 20 ± 1.57 kg from both sex, fed different forms of creep feed for three month. This study was designed by factorial randomized completely block design 2x2. The first factor was type of creep feed form (mash and pellet), and the second factor was the type of goat breeds (Etawah crossbred and Senduro). The complete ration consisted of 70% creep feed containing black soldier fly (BSF) meal and BSF oil plus 30% elephant grass. The variables observed were feeding behavior nutrient consumption, digestibility, blood metabolites, and performance. Results: The results showed that there was no interaction between the creep feed forms and the goat breeds in all variables. The form of creep feed had a significant effect on prehension and mastication and the pellet form had higher prehension and mastication compare to mash from but it had no significant effect on nutrient consumption and digestibility. Performance and blood metabolites were same in all treatments, except for the feed efficiency of Senduro goats had higher than Etawah crossbred goats. Conclusion: In conclusion, giving creep feed containing BSF larvae meal and oil in starter concentrate as pellet forms resulted a lower prehension and higher mastication, but has higher prehension and lower mastication for mash type. The performance and blood metabolites were are not different in all treatment groups.

Application Of Microbubble Technology To Increase Oxygen Content In The Aquaculture Of Tambaqui (Colossoma Macropomum)

The oxygen consumed is used to oxidize food substances to produce energy. Therefore, the metabolic rate is usually indicated by the rate of oxygen consumption per time unit. In most intensive aquaculture systems, oxygen content is widely used due to the high stocking density and maximum feeding rates. This study aimed to evaluate the growth performance of freshwater pomfret (Colossoma macropomum) treated with increased oxygen in two different systems. The study was conducted in a laboratory scale by applying T-test data analysis. The difference of treatment level applied in the comparison of aeration and microbubble consists of two treatments and three replications. The researcher used commercial floating pellets PF0 with 25% protein content, the feeding rate was 5% of the biomass. The feed was given daily during the culture for two times a day. Data of the study were analyzed using T-test on the Statistical Product and Service Solutions (SPSS) software Version 17.0. Results of the study showed that aeration system using microbubble resulted in dissolved oxygen (DO) of 6.5 ± 0.17, 100% pomfret fish survival rate (SR), Survival Growth Rate (SGR) of 1.83 ± 0.24, Feed Conversion Ratio (FCR) of 1.37 ± 0.17, Protein Efficiency Ratio (PER) of 2.79 ± 0.37, Feed Utilization Efficiency (FUE) of 0.67 ± 0.09, Absolute Weight Growth of 52.02 ± 1.60; it was better than using aeration. This study has developed a model of freshwater pomfret fish aquaculture to provide growth value.

Effects of Low-Pressure Systems on Temperature, Humidity, Egg Production, and Feed Utilization Efficiency in Large-Scale Poultry Houses during Summer.

Low-pressure systems (LPSs) are among the most critical weather systems, producing excessive precipitation that causes air temperatures to drop and rise considerably. Acute temperature changes directly affect poultry feed intake (FI) and laying performance. To explore the effects of LPSs on hens, the parameters of air temperature, relative humidity, egg production, and feed utilization efficiency were evaluated during different LPSs in three houses. Results indicated that about 2.8 ± 0.7 d, 2.4 ± 0.5 d, and 2.4 ± 0.5 d before the LPS landfall in houses 1, 2, and 3, respectively, the indoor air temperature started to decrease, with the average decreases being 1.7 °C ± 0.4 °C, 2.4 °C ± 0.6 °C, and 1.8 °C ± 0.4 °C, respectively. Significant differences were observed between different LPSs for reducing indoor air temperature (p < 0.05) in the three houses. In house 1, the egg production rates (EPRs) were decreased by 6.6% and 1.1% when LPSs 1 and 2 landed. The average egg weight (AEW) and FI during the LPS landfall were significantly higher than those before the LPS landfall (p < 0.01). Under successive LPSs landfall in the three houses, the EPRs initially reduced by 3.9%, 4.0%, and 0.5%, respectively, but the second LPS event increased the EPRs by 1.8%, 5.3%, and 1.0%, respectively. Furthermore, the LPS landfall increased the feed conversion ratio (FCRe) in the three houses, all above 2.00. In conclusion, LPSs can reduce heat stress, lower the EPRs, and lead to higher FI, FCRe, and AEW.

Effect of Stocking Density on Growth, Biochemical Composition, and Blood Parameters in the Pacific Shortfin Eel (Anguilla bicolor pacifica) Elvers

This study examined the effect of stocking density on growth, biochemical composition, and blood parameters of the Pacific shortfin eel Anguilla bicolor pacifica. Elvers (1.95 ± 0.14 g body weight) were randomly stocked in indoor tanks and reared over 186 d at three stocking densities (0.3, 0.6, and 0.9 kg m-3) set up in triplicates. Except for survival and biometric indices, elvers maintained at 0.3 and 0.6 kg m-3 densities exhibited higher growth and feed utilization than those held at 0.9 kg m-3. Yield increased with stocking density, which were significantly higher at 0.6 and 0.9 kg m-3. RNA/DNA ratio did not reflect growth rate, but trends in survival and RNA/DNA ratio with stocking density were positively related. In contrast to body proximate composition, increasing stocking density resulted in significantly higher erucic acid (22:1n-9) and total saturated fatty acid levels at 0.6 and 0.9 kg m-3 densities, respectively. Serum glutamic pyruvic transaminase activity was significantly elevated at 0.6 kg m-3, while total protein, glucose, and triglycerides slightly decreased with increasing stocking density. Results suggest that Pacific shortfin eel elvers can be reared in indoor tanks at a stocking density of 0.3 – 0.6 kg m-3 to achieve acceptable growth, feed performance, and health condition.

Influence of a peptidoglycan-enriched diet on growth performance, feed utilization and immune response in striped catfish (Pangasianodon hypophthalmus)

Influence of a peptidoglycan-enriched diet on growth performance, feed utilization and immune response in striped catfish (Pangasianodon hypophthalmus)

Effect of Fermented Rice Bran as a Feed Ingredient on Growth Performance, Feed Utilization, Body Composition, Intestinal Microbiota, and an Economic Evaluation of the Grey Mullet (Mugil cephalus)

Effect of Fermented Rice Bran as a Feed Ingredient on Growth Performance, Feed Utilization, Body Composition, Intestinal Microbiota, and an Economic Evaluation of the Grey Mullet (Mugil cephalus)

Tank color affects growth, feed utilization efficiency, coloration, and biochemical composition of juvenile giant trevally (Caranx ignobilis Forsskål, 1775)

Tank color affects growth, feed utilization efficiency, coloration, and biochemical composition of juvenile giant trevally (Caranx ignobilis Forsskål, 1775)

Effect of thymol on the efficiency of feed utilization and compensatory growth in severe feed-restricted lambs.

The present study aimed to evaluate the effect of thymol on growth performance and apparent total tract digestibility of nutrients in severely feed-restricted lambs. Twenty-one male Baluchi lambs were randomly blocked by live weight into three groups: control without feed restriction (CON), feed restricted (FR), and feed restricted plus thymol (FR + T). The lambs underwent a four-week feed restriction period followed by four weeks of realimentation. Thymol was administered daily to the FR + T group during the feed restriction period. Average daily gain (ADG), average daily feed intake, feed efficiency (FE), partial efficiency of maintenance (PEM), and residual feed intake (RFI) were measured as growth performance parameters. Results showed that the severe feed restriction had adverse effects on ADG and FE, but improved PEM (P < 0.05). The effects of thymol administration on ADG, FE, PEM, and apparent total tract digestibility were not significant (P > 0.05). However, the lambs that received thymol during the feed restriction period showed a negative RFI during realimentation (P < 0.05). Overall, these findings suggest that feed restriction as well as thymol may have the potential to improve efficiency of feed utilization in growing lambs. However, this positive effect is independent of the improvement in nutrient digestibility.

Comparison of Pediococcus pentosaceus YC64-fermented soybean meal and raw soybean meal in diets for Nile tilapia: Growth performance, feed utilization, and intestine health

Fermentation is a promising approach for improving the utilization of soybean meal (SM) by aquaculture fish, and the strain is the core of microbial fermentation processes. Herein, Pediococcus pentosaceus YC64, an autochthonous probiotic isolated from the intestine of Nile tilapia (Oreochromis niloticus), was applied to the fermentation of raw SM. In an eight-week feeding trial, tilapia juveniles were divided into two treatments fed on diets with 0 % (Control) and 100 % of SM protein replaced by fermented SM (FSM). Results showed that solid-state fermentation improved SM quality indicated by increased acid-soluble protein contents. Fish fed the FSM diet had significantly higher weight gain, feed efficiency, and protein efficiency compared to those fed the SM diet. Furthermore, whole-body protein content significantly increased in the FSM-fed fish, accompanied with the increased amino acid transport and reduced protein catabolism. Texture profile analysis indicated that fish fed the FSM diet had reduced muscle hardness compared with the control, which was associated with changes in collagen deposition and myofiber development. Moreover, feeding an FSM diet enhanced goblet cell proliferation and stimulated mucin secretion, ultimately leading to improved intestinal tight junctions and reduced inflammatory response. Besides, the FSM diet feeding altered intestinal microbiota community, characterized by increased abundance of Pediococcus. Overall, P. pentosaceus YC64 exhibits promise as a fermentation strain in the production of FSM. The FSM performed better than SM in improving the growth performance, feed utilization, and intestine health of Nile tilapia.

Potential Development Ability of Residual Zoites, a Second-Generation Meront, Inducing Long-Term Infection by the Mouse Eimerian Parasite, Eimeria krijgsmanni.

Coccidiosis caused by eimerian parasites results in lethal watery or bloody diarrhea in hosts, and markedly impairs the growth of and feed utilization by host animals. We previously investigated detailed the life cycle of Eimeria krijgsmanni as a mouse eimerian parasite. Only second-generation meronts, as an asexual stage, were morphologically detected in the epithelium of the host cecum for at least 8 weeks after infection, even though oocyst shedding finished approximately 3 weeks after infection. The presence of zoites was of interest because infection by eimerian parasites is considered to be self-limited after their patent period. To clarify the significance of residual second-generation meronts in E. krijgsmanni infection, we performed infection experiments using immunocompetent mice under artificial immunosuppression and congenital immunodeficient mice. The number of oocysts discharged and the duration of oocyst discharge both increased in immunosuppressed mice. In immunodeficient mice, numerous oocysts were shed over a markedly longer period, and oocyst discharge did not finish until 56 days after inoculation. The present results suggest that the second-generation meronts survived in the epithelial cells of the cecum after the patent period, thereby contributing to extended infection as an asexual stage. The results obtained on E. krijgsmanni indicate that infections by Eimeria spp. are not self-limited and potentially continue for a long period of time.

Manipulation impacts of jack mackerel meal in low fish meal diets on growth, feed availability, and biochemical composition of olive flounder (Paralichthys olivaceus) and economic analysis

AbstractManipulation 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.

Growth of Bamboo Lobster (Panulirus versicolor; Latreille, 1804) Fed with Feed Made from Sosodek Fish Meal (Atherinomorus lacunosus)

Bamboo lobster (Panulirus versicolor) is a marine commodity with promising prospects for aquaculture development. Feed is a critical issue in the growth of P. versicolor, necessitating an effective, affordable solution that promotes optimal growth. This study aimed to examine the use of sosodek fish meal (A. lacunasus) as a nutrient source to enhance the growth of P. versicolor. Specimens of P. versicolor (weighing 79.97±38 g) were obtained from local fishermen in Togean District, Tojo Una-Una Regency, Central Sulawesi. The experiment tested the use of sosodek fish meal as a feed ingredient at different percentages: 0% (control), 10% (A), 20% (B), and 30% (C). The lobsters were kept in containers with 25 liters of seawater, with one lobster per container, and each treatment was replicated three times. Feed was given at 5% of body weight, three times daily. Body weight was measured every two weeks. Water quality was maintained within a range suitable for P. versicolor. The results indicated that weight gain and daily growth rates, from highest to lowest, were observed in treatment C (11.84 g and 0.49%/day), B (7.4 g and 0.21%/day), A (2.82 g and 0.09%/day), and control (2.38 g and 0.08%/day). Feed conversion ratios, from lowest to highest, were recorded as C (13.1), B (25.1), A (71.9), and control (64.0). Feed utilization efficiency, from highest to lowest, was seen in treatment C (10.28%), B (4.32%), A (1.85%), and control (1.72%). Survival rates for all treatments were 100%. The analysis showed that individual weight gain, daily growth rates, and feed utilization efficiency were significantly higher, and feed conversion ratios were lower in treatment C (30% sosodek fish meal) compared to other treatments (P&lt;0.05). Utilizing 30% sosodek fish meal as feed ingredient significantly enhances the growth of P. versicolor.

Vitamin D3 alleviates the damage caused by high-fat and maintains lipid metabolism homeostasis in hepatopancreas by promoting fatty acid β-oxidation of Portunus trituberculatus

The purpose of present study was to evaluate the effects of vitamin D3 supplementation in high-fat diet on growth performance, calcium and phosphorus in tissue, immunity and lipid metabolism, and to explore whether adding vitamin D3 to high-fat diet can alleviate the adverse effects of high-fat diet on swimming crab (Portunus trituberculatus). The three experimental diets were normal fat diet (NFD, 9.35 % fat, 45.53 % protein), high fat diet (HFD, 14.69 % fat, 44.93 % protein) and high fat diet supplemented with 0.47 mg/kg VD3 (HFD+VD), respectively. A total of 108 healthy swimming crabs with an initial body weight of 9.42±0.13 g were selected for an 8-week feeding trial. The results showed that crabs fed with HFD+VD diet exhibited significantly higher percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE) and molting rate (MR) compared to those fed with HFD diet (P < 0.05). It was observed from hepatopancreas crude lipid content, TG content and hepatopancreas sections that HFD caused hepatopancreatic cell damage and abnormal lipid accumulation (P < 0.05), however, there were no significant differences in hepatopancreas crude fat content, TG content and hepatopancreas section observation between HFD+VD group and NFD group (P > 0.05). Crabs fed HFD diets with or without VD3 significantly down-regulated the expression of genes related to fatty acid transport, such as fabp9 and lpr1 in hepatopancreas (P < 0.05), moreover, the expression of genes related to fatty acid β-oxidation (cpt2 and acox1) were significantly up-regulated and genes related to lipid synthesis (fas and 6pgd) were significantly down-regulated in the hepatopancreas of the crabs fed with HFD+VD diet compared to those fed with HFD diet (P < 0.05). In conclusion, the results of present study indicated that a high-fat diet can cause deformation and rupture of hepatopancreas cells through abnormal lipid accumulation, thereby causing associated inflammation, leading to large calcium and phosphorus deposits in hemolymph and muscle, however, high fat diet supplemented with vitamin VD3 mainly enhanced the β-oxidation of fatty acids, inhibited lipid synthesis, alleviated abnormal lipid accumulation, and thus maintained the balance of lipid metabolism in hepatopancreas cells and promoted growth performance and feed utilization for swimming crab.

Comparative growth, survival, and feed conversion factor of the F1 generation of two new strains of tilapia Oreochromis niloticus produced by mass selection

Growth, survival, and use of feed of the F1 generation of two new strains of tilapia Oreochromis niloticus (GenBank Strain Y = OK078792 to OK078796 and Strain A = OK078797 to OK078807) produced by mass selection was compared with a known fast-growing commercial strain in Mexico (GenBank Strain Q = OR744820 to OR744838), during a grow-out phase of 165 days. Genetic variability including observed (Ho) and expected (He) heterozygosity, inbreeding coefficient (Fis), and paired comparisons of strain fixation index (Fst) of the three strains were also compared, and an additional analysis of molecular variance (AMOVA) was performed. Twelve hapas of 8.2 m3 (four for each strain) were stocked at a density of 25 org m−3 of 4.58 ± 0.67 g, which were fed with 45 to 25% crude protein feed under a dynamic feeding scheme of 8 to 3% live weight. Growth was estimated by growth rates in weight and length, and by the weight-specific growth rate (SGR). The use of feed was estimated by the total feed consumption rate and the feed conversion factor (FCF). Results indicate no significant differences (P > 0.05) in growth parameters of the three strains, except in SGR which was significantly higher in the control strain (Q) (2.75% day−1) as compared with strains Y and A (2.51 and 2.59% day−1 respectively). The average final weight and size of the fish were 314.6 ± 11.8 g and 25.5 ± 0.4 cm respectively. No significant differences (P > 0.05) were found in survival and feed utilisation among strains, with average values of 96.4% survival, feed consumption of 3.91 g day−1, and FCF of 2.08. Results of genetic diversity indicate that there were no significant differences (P > 0.05) in Ho and He of the three strains, with average values of 0.310 and 0.280 respectively. Fis values were negative and similar for the three strains, with a mean value of −0.109 which indicates no consanguinity in their populations. Finally, the paired comparisons of Fst were significantly different (P < 0.001), showing relatively low values but different from 0 (Y vs. A = 0.025, A vs. Q = 0.041 and Y vs. Q = 0.055), indicating slight but significant population differentiation between strains. In conclusion, the performance and genetic variability of the F1 generation of the two new strains suggest that valuable broodstock is now available for mass production of fry, with similar performance as to one of the best strains of tilapia in Mexico.

Fermented aquatic weed meal (FAWM) as a protein source in Asian Catfish Clarias batrachus diets: Impacts on growth, blood chemistry profile, liver and gut morphology and economic efficiency

The global aquaculture industry is increasingly seeking sustainable alternatives to fishmeal (FM) due to its high price and shortfall in supply. In this context, fermented aquatic weed meal (FAWM) could emerge as a viable plant protein source for aquafeed. Four isoproteic diets [30 % crude protein (CP)] were formulated, incorporating 50 % total protein from FAWM comprising fermented Azolla diet (D1), Pistia diet (D2), and Eichhornia diet (D3). The control diet (D0) did not contain FAWM. At the end of the 90 days feeding trial, their growth performance, whole-body proximate composition, gut microbial load, haemato-biochemical indices, liver and gut health, and economic efficiency were determined. Fish fed with D0 had significantly (p < 0.05) improved growth performance and feed utilization compared to other treatment groups. Meanwhile, the fish supplemented with D1 diet exhibited significantly (p < 0.05) higher final weight (g), specific growth rate (%/day), weight gain (%), total biomass (g), and protein efficiency ratio among the FAWM dietary groups. The D1 group also demonstrated the significantly (p < 0.05) highest whole-body CP (64.27 ± 0.40 %) and lower crude lipid (8.24 ± 0.28 %) compared to other test diets. The total bacteria (TB) and lactic acid bacteria (LAB) in the fish gut were found to be significantly (p < 0.05) higher in D1 group. Furthermore, most of the hemato-biochemical indices of fish were significantly (p < 0.05) affected by FAWM inclusions, with few exceptions. The histological findings indicated that amongst the FAWM groups, D1 fish exhibited improved intestinal health. Nonetheless, the gut of the control fish demonstrated substantially (p < 0.05) lower villi width and crypt depth than other treatments. The D1 and D2 diet groups had significantly improved liver health. Moreover, FAWM inclusion enhanced economic efficiency by considerably reducing farm feed cost (US$/kg) and increasing return on investment (%). In summary, dietary inclusion of fermented Azolla pinnata (D1) protein at 50 % in aquafeed promoted feed utilization, growth, health, and farm economics of Asian catfish fingerlings compared to other FAWM diets.

Evaluation of dietary yeast derived mannan oligosaccharide for pacific whiteleg shrimp Penaeus vannamei: Effects on growth performance, immune response, hepatopancreas morphology and resilience to infection against Vibrio parahaemolyticus

With trends towards low fishmeal and higher plant ingredient-based diets for shrimp, there is consequently greater demand on feed additives to bolster the protein and nutrient profile quality for achieving more efficiency. Also, there is a need to enhance innate immunity and resilience to infection under intensive shrimp production scenarios. This investigation tested incremental levels 0, 0.2; 0.4; 0.6 and 0.8 % of a commercial yeast cell wall extract mainly comprising β-glucan and mannan oligosaccharides (MOS) (YM, YeaMOS, Angel Yeast, Yichang, Hubei, China) for post-larval shrimp Penaeus vannamei in isonitrogenous and iso-lipidic diets with proteinaceous plant ingredients amounting to 50 % contribution of the diet formulation. After 60 d, growth and feed utilization performance were not significantly affected in shrimp in terms of weight gain or FCR, but due to much higher survival, total biomass in groups of shrimps fed with dietary YM was higher compared to the control treatment. A sequential specific pathogen challenge test with Vibrio parahaemolyticus at final dose of 104 CFU mL−1 resulted in a marked improvement in survival against the control group with much enhancement at the inclusion level of 0.4 % YM (p<0.05). Before challenged, the total haemocyte count (THC) and the relative gene expression of Prophenoloxidase (ProPO) were higher in the group of shrimps fed with YM. Likewise, after infection, the amount of THC and ProPO remained better in the group of shrimps fed with YM. However, the 0.8 % YM treatment did not significantly differ from the control for phagocytic activity and index. The histomorphology condition of the hepatopancreas of shrimp before the infection for all treatments appears normal without significant numbers of hepatopancreatic tubules (T) and epithelial cell vacuoles (V). After pathogen challenge, all shrimp exhibited severe necrotic cell damage and massive sloughing of hepatopancreatic tubule epithelial cells into the lumen. Overall, giving YM as feed additives can improve the shrimp biomass and health, with the use of 0.4 % inclusion levels in practical diets for shrimp P. vannamei become the optimum dose to develop more efficient aquafeed production.

Dietary monosodium glutamate affects the growth and feed utilization of Eriocheir sinensis by regulating the appetite related genes expression

This study assessed the impacts of monosodium glutamate (MSG) on the growth performance, feed utilization, feed intake, and appetite regulation of Chinese mitten crab, Eriocheir sinensis. A total of 240 juvenile crabs (9.16 ± 0.21 g) were assigned to six experimental diets supplemented with MSG at 0 %, 0.20 %, 0.39 %, 0.59 %, 0.78 % and 0.98 %. The results demonstrated that 0.59 % MSG supplementation significantly enhanced the weight gain rate (WGR), specific growth rate (SGR), and feed utilization of juvenile E. sinensis by increasing feed intake (FI) (p < 0.05). Moreover, dietary moderate MSG improved the mid-intestine morphology, such as height of microvillus (HMV), width of microvillus (WMV), and thickness of muscularis (TM). The qRT-PCR analysis demonstrated that the mRNA expression levels of the appetite-stimulating neural signals agouti related protein (agrp) and ghrelin were increased significantly by dietary moderate MSG (p < 0.05). Conversely, the mRNA levels of protein kinase B (akt), target of rapamycin (tor) and 4E-binding protein (4e-bp), as well as appetite-suppressing neural signals pro-opiomelanocortin (pomc), corticotropin-releasing factor (crf) and peptide yy (pyy) were significantly down-regulated (p < 0.05). The two-slope broken-line regression analysis of SGR in relation to dietary MSG levels suggested that the optimum dietary MSG level for juvenile E. sinensis was 5.6 g/kg. Collectively, MSG may potentially stimulate or suppress the appetite regulation neural signals/hormones, thereby modulating the feeding behavior of E. sinensis.

Microplastics accumulation in gut and revealing their impacts on nutritional quality and health of freshwater carp, Catla catla

The widespread presence of microplastics (MPs) in aquatic ecosystems raises concerns about their potential harm to aquatic life, particularly fish, which are a vital source of protein for human consumption. It emphasizes the importance of examining their occurrence and impacts. The focus of this study was to find out deleterious effects of polylactic acid MPs (PLA-MPs) on the Catla catla fingerlings by observing their growth, body composition, digestibility, histopathology, blood health, and mineral analysis. Utilizing sunflower meal (SFM) as the basal diet, six test diets were formulated, incorporating distinct MP concentrations: control (no MPs), 0.5 %, 1 %, 1.5 %, 2 %, and 2.5 %. These test diets were tested in three replicates of 15 fingerlings per tank and fed at 5 % equivalent of their live wet body weight for 90 days. After exposure to 2.5 % MPs, C. catla, fingerlings showed a significant decline in growth rate and feed utilization. Increased FCR and decreased WG (g) were observed in 2.5 % PLA-MPs. As MP levels increased, nutrient digestibility and minerals content decreased. PLA-MPs increased body fat and moisture, but decreased protein and ash content. MP exposure leads to significant changes in hematological parameters, including decreased RBCs, Hb, PLT, PCV, and MCHC, and increased WBCs, MCH, and MCV. Furthermore, histopathological examination of the gut showed increased intestinal abnormalities at the 2.5 % PLA-MPs concentration. This study underscored the adverse effects of PLA-MP pollution on the overall health performance of C. catla fingerlings.