Protein Retention Rate Research Articles

Immunogenicity of glycine nanoparticles containing a chimeric antigen as Brucella vaccine candidate

PurposeBrucellosis as a worldwide zoonotic illness affect domestic animals and humans doesn't have any vaccine for the prevention of infection in humans yet. The aim of this study was to evaluate the specific immune response following the administration of glycine nanoparticles as adjuvant and delivery system of a chimeric antigen contained trigger factor, Omp31, and Bp26 in murine model.Materials and MethodsThe chimeric antigen of Brucella was cloned and expressed in Escherichia coli (E. coli) BL21 (DE3). Purification and characterization of recombinant protein was conducted through Ni-NTA (nickel-nitrilotriacetic acid) agarose, SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis), and Western blot. Nanoparticle characteristics including morphology, particle size distribution, zeta potential, protein retention rate, and release rate were measured in vitro. Subsequently, nanoparticle contained antigen was administered to mice and blood sample was taken to measured the antibody level.ResultsThe protein retention in the nanoparticles was successfully done and the nanoparticle characteristics were appropriate. The average size of glycine particles containing antigen was about 174 nm, and the absorption of protein was approximately 61.27% of the initial value, with a release rate of approximately 70% after 8 hours. Enzyme-linked immunosorbent assay result proved that the immunized sera of mice which were administered with nano-formula contains high levels of antibodies (immunoglobulin G) against recombinant chimeric antigen and also a high level of mucosal antibody (immunoglobulin A) in the oral group, which showed a desirable immunity against Brucella.ConclusionThe results showed that chimeric antigen-loaded glycine nanoparticles can act as a vaccine candidate for inducing the cellular and humoral immune response against brucellosis.

Water-in-oil microemulsion: effect of Desmodium intortum protein isolate–emulsifier interaction, and its stability

ABSTRACT Water-in-oil (W/O) microemulsions exhibit delivery matrix and exhibit poor lipid solubility. Therefore, increasing the stability of W/O microemulsions is necessary to broaden their applications. In our experiment, a protein microemulsion system was constructed and its stability was investigated. The effects of surfactants, co-surfactants, quality ratio of them (Km) and hydrophilic-lipophilic balance (HLB) values were determined by using the pseudo-ternary phase diagrams and the area of microemulsions (MEs) as the indexes. The results showed that MEs’ stability was the best when the limonene was used as oil phase, Tween 20 + span 80 as the surfactant, and anhydrous alcohol as co-surfactant, if and only if HLB = 6.0 and Km = 3:1. Under this condition, the area of micro-emulsion was the largest, and the quality of microemulsion was better when the mass ratio of oil phase and emulsifier was 7:5.The protein microemulsion was a water-in-oil type, with a particle size of 1.41 ± 0.03 μm, containing 1127.37 ± 30.87 μg/g of proteins. Moreover, the temperature, light, and sample observation tests showed that the solution’s protein retention rate was lower than those in the microemulsion. Low-concentration NaCl, less than 9% of glucose and maltose exerted no significant influence on the protein microemulsion stability.

Improvement of filtration performance of polyvinyl chloride/cellulose acetate blend membrane via acid hydrolysis

AbstractBased on the hydrophilicity and biodegradability of cellulose acetate (CA), polyvinyl chloride (PVC)/CA blend membrane was prepared by solution comixing and phase transformation method. Then the CA in the blend membrane was partially hydrolyzed under acidic conditions to improve the hydrophilicity of the blend membrane, so as to improve the filtration performance of the PVC/CA blend membrane. The properties of the membranes were systematically characterized by Fourier transform infrared spectroscopy, differential scanning calorimeter, and scanning electron microscopy (SEM). The porosity, water contact angle, pure water flux (PWF), protein retention rate, and mechanical properties of the membrane were measured, and the effect of hydrolysis on the filtration performance of the blend membrane was analyzed. The results showed that the hydrophilicity and porosity of the blend membrane increased, the PWF and protein rejection rate enhanced after acid catalyzed hydrolysis, while the mechanical properties of PVC membrane were maintained. This simple preparation method endows PVC/CA blend membrane with desirable filtration performance, and also helps to overcome the disadvantages of poor hydrophilicity and easy pollution of pure PVC membrane.

Optimal form of yeast cell wall promotes growth, immunity and disease resistance in gibel carp (Carassius auratus gibelio)

A 63-day feeding trial was conducted to explore dietary yeast cell wall (YCW) on growth, immunity and disease resistance against Aeromonas hydrophila in gibel carp (Carassius auratus gibelio var. CAS Ⅲ) (initial body weight: 8.49 ± 0.27 g). Four isonitrogenous and isoenergetic diets were formulated to contain 0 % or 0.4 % three types of yeast cell wall (YCW) (termed as YCW0, YCW1, YCW2 or YCW3, respectively). Fish were randomly divided into 4 feeding groups in triplicates of 22 fish in each tank. Results showed that the highest final body weight was observed in fish fed YCW3 diet than the control (P < 0.05). Compared to the control group, significantly higher FE was found in groups of YCW2 and YCW3 (P < 0.05). There were no significant differences in feeding rate, specific growth rate, protein retention rate and energy retention rate among treatments (P > 0.05). Dietary supplementation of YCW decreased condition factor, hepatosomatic index and viscerosomatic index (P < 0.05). Dietary addition of YCW3 significantly increased serum complement C3 compared to control group (P < 0.05). The relative expression of complement C3 in liver was significantly upregulated in fish fed YCW3 supplemented diet (P < 0.05). Dietary YCW1 significantly increased lysozyme C mRNA level (P < 0.05). The relative expressions of TNF-α1 and IL-8 were not significantly affected by YCW inclusion in the diet (P > 0.05). Hepatic IL-1β and TGF-β expressions were significantly down-regulated in the fish fed YCWs (P < 0.05). Furthermore, dietary administration of YCW1 and YCW3 could to some extent improve disease resistance against bacterial challenge. Based on growth performance and immunity, 0.4 % YCW3 was recommended in the gibel carp diet.

Effect of dietary selenium on postprandial protein deposition in the muscle of juvenile rainbow trout (Oncorhynchus mykiss).

Se, an essential biological trace element, is required for fish growth. However, the underlying mechanisms remain unclear. Protein deposition in muscle is an important determinant for fish growth. This study was conducted on juvenile rainbow trout (Oncorhynchus mykiss) to explore the nutritional effects of Se on protein deposition in fish muscle by analysing the postprandial dynamics of both protein synthesis and protein degradation. Trout were fed a basal diet supplemented with or without 4 mg/kg Se (as Se yeast), which has been previously demonstrated as the optimal supplemental level for rainbow trout growth. After 6 weeks of feeding, dietary Se supplementation exerted no influence on fish feed intake, whereas it increased fish growth rate, feed efficiency, protein retention rate and muscle protein content. Results of postprandial dynamics (within 24 h after feeding) of protein synthesis and degradation in trout muscle showed that dietary Se supplementation led to a persistently hyperactivated target of rapamycin complex 1 pathway and the suppressive expression of numerous genes related to the ubiquitin-proteasome system and the autophagy-lysosome system after the feeding. However, the ubiquitinated proteins and microtubule-associated light chain 3B (LC3)-II:LC3-I ratio, biomarkers for ubiquitination and autophagy activities, respectively, exhibited no significant differences among the fish fed different experimental diets throughout the whole postprandial period. Overall, this study demonstrated a promoting effect of nutritional level of dietary Se on protein deposition in fish muscle by accelerating postprandial protein synthesis. These results provide important insights about the regulatory role of dietary Se in fish growth.

Growth performance of myostatin knockout red sea bream Pagrus major juveniles produced by genome editing with CRISPR/Cas9

We have reported the production of myostatin (Pm-mstn) complete knockout red sea bream (Pagrus major) using CRISPR/Cas9, and the Pm-mstn mutant exhibited a 17% increase in skeletal muscle. However, important characteristics in aquaculture production, such as the growth rate and the amount of feed required for growth have not been clarified. In this study, we conducted a feeding trial using apparent satiation feeding during the juvenile stage and compared growth performance metrics including; weight gain, feed efficiency, apparent protein and lipid retention rates of the Pm-mstn mutants with wild-type fish (WT). Experimental fish were produced via artificial insemination from single male and female broodfish of heterozygous Pm-mstn mutants and reared in one tank until the start of the trial. Genotypes of 356 full sib fish were identified, and the WT and the homozygous mutant (HM) were used for the trial. Seventeen fish from WT and HM (mean body weight 41.1 ± 0.3 g and 42.7 ± 0.3 g, respectively) were randomly distributed into each of 100 L circular tanks and set in triplicate for each genotype. Fish were fed twice daily to apparent satiation with each respective diet at 08:00 and 13:00 six days per week for 8 weeks. Weight measurement of all experimental fish was conducted bi-weekly. Five fish at day zero from each genotype and 5 fish from each tank at the final day of the trial were sampled for whole-body proximate analysis. At the end of the trial, weight gain, specific growth rate, and feed efficiency were significantly higher in the HM group than that in the WT group, and there was no significant difference in the daily feed intake. The protein efficiency and apparent protein retention were significantly higher in the HM than for the WT. These results suggest that HM fish feed similarly to that of WT fish during the juvenile stage. However, HM fish have a higher ability to convert feed efficiently and accumulate ingested protein, resulting in better overall growth.

Comparison of dehulled, fermented and enzyme-treated soybean meal in diets for largemouth bass, Micropterus salmoides: Effects on growth performance, feed utilization, immune response and intestinal morphology

A 67-day feeding trial was conducted to evaluate the nutritional value of dehulled soybean meal (DSM), fermented soybean meal (FSM), and enzyme-treated dehulled soybean meal (EDSM) in diets prepared for cultured largemouth bass (Micropterus salmoides). Triplicate groups of fish were fed diets composed of different soybean meal twice daily. The results showed that the inclusion of EDSM led to the best specific growth rate (SGR), while the SGR of fish fed with soybean meal fermented by a mixture of microorganisms (Lactobacillus bulgaricus, Saccharomyces cerevisiae, and Bacillus subtilis) (FSMI) was significantly higher than that of fish fed with soybean meal fermented with Saccharomyces cerevisiae (FSMII), and with untreated soybean meal. Moreover, DSM resulted in the lowest apparent digestibility coefficient of protein and lipid, which may account for the observed reduction in the feed efficiency ratio and protein efficiency ratio as well as the impaired growth performance. The fish fed the diet with DSM exhibited the lowest protein retention rate but the highest lipid retention rate, which may be related to the variation in body composition in combination with feed utilization. The activity of lysozyme and classical complement pathway in fish fed diets with EDSM and FSMI was significantly higher than that in the DSM group, and the DSM group also produced the lowest hematological index value. Moreover, specific histopathological changes were observed in distal intestine of fish fed the diet with DSM. The results showed that fermentation and enzymatic pre-processing can improve the nutritional value of soybean meal, possibly be reducing anti-nutritional factors. For largemouth bass, the EDSM performed better than FSM in elevating growth performance and feed utilization under the applied experimental conditions.

Impact of milk and nutrient intake of piglets and sow milk composition on piglet growth and body composition at weaning

The main objective of this study was to evaluate the impact of milk intake, milk composition, and nutrient intake on piglet growth in lactation and body composition at weaning. To evaluate the body composition of piglets, data from one experiment (44 Danish Landrace × Yorkshire × Duroc piglets) were used to develop prediction equations for body pools of fat, protein, ash, and water based on live weight and deuterium dilution space (exp. 1). Furthermore, a total of 294 piglets (Danish Landrace × Yorkshire × Duroc) from 21 sows of second parity were included in a second experiment (exp. 2). In exp. 2, piglet live weight was recorded on days 3, 10, 17, and 25 of lactation. On the same days, the milk intake and body composition were measured, using the deuterium oxide (D2O) dilution technique. Piglet weight gain was highly positively correlated with the intake of milk and the intake of milk constituents each week and on an overall basis having r values ranging from 0.65 to 0.93 (P < 0.001). When evaluating regressions for piglet growth, the milk intake in combination with the milk protein concentration explained 85% and 87% of the total variation in piglet gain in the second and third week of lactation, respectively, whereas milk intake was the only predictor of piglet gain in the first week of lactation explaining 81% of the variation. Fat, protein, and energy retention rates were all highly positively correlated with the daily intake of milk and intake of milk nutrients with r values ranging from 0.76 to 0.94 (P < 0.001). Piglet gain and retention rates were rather weakly correlated with the milk composition with r values ranging from 0.01 to 0.50 (being either negative or positive). Curvilinear response curves were fitted for live weight gain and body fat content at weaning in response to milk protein concentration, showing that live weight gain was slightly greater and body fat content was slightly lower at 4.9% milk protein, but it should be emphasized that the quadratic effects did not reach significance. Body fat content at weaning was positively related with the intake of milk (R2 = 0.44, P < 0.001) and milk fat (R2 = 0.46, P < 0.01). In conclusion, milk intake had a major impact on the piglet growth rate, and milk fat intake greatly influenced the body fat percentage at weaning, whereas milk composition per se only played a minor role for these traits.

Feeding management strategies to optimize the use of suspended feed for Nile tilapia ( Oreochromis niloticus ) cultivated in bioflocs

Feeding strategies of tilapia (initial average weight: 32 g) cultivated with Biofloc technology (BFT) (carbon source: sugarcane, C:N ratio: 6:1) for 56 days were studied. A 4 × 3 factorial experimental design was used with four feeding frequencies (one, two, three and four times a day) and three feeding rates (50%, 75% and 100% consumption in relation to apparent satiety), with four replicates. Lower levels of dissolved oxygen, protein retention rate and body protein content were found in fish fed once a day. The reduction in feeding rate resulted in lower average final weight and reduced growth but promoted a decrease in the concentration of total ammonia nitrogen, solids, hepatosomatic index and body lipids. We found better efficiency of protein utilization at 75% feed. The nutritional value of the floc was not affected by the feeding frequency, and the feeding rate reduction from 100% to 75% did not alter the protein content of the floc. Thus, twice-daily feeding frequency is sufficient for Nile tilapia fingerlings reared in BFT. Although the feeding rate of 100% satiety has led to better performance, it may not be the best option in BFT due to higher feed conversion and reduction of water quality.

Influence of collagen hydrolysate components on fabrication of collagen/PVA composite fiber

In order to prepare a collagen/PVA composite fiber with collagen hydrolysate, the influence of the molecular weight and ash content of the collagen hydrolysate on the spinning properties and fabrication of the composite fiber should be studied. In this work, collagen with various molecular weights and different ash contents was first blended with PVA for fabrication of different collagen/PVA composite fibers. Next, protein retention rates, titer, tensile strength, elongation at break, and initial modulus of the composite fibers were characterized. Meanwhile, the degree of crystallinity of the composite fiber was measured by X-ray diffraction and the cross-section morphology was observed by a scanning electron microscope. The results show that the cross section of the collagen/PVA composite fiber has a skin-core structure and the collagen hydrolysate mainly distributes on the surface of the composite fiber. A molecular weight of collagen hydrolysate range from 10,000 Da to 100,000 Da is suitable for fabrication; however, if the collagen hydrolysate molecular weight is lower than 10,000 Da, there is obvious protein loss during spinning. In addition, the inorganic salt and ash content in the spinning collagen hydrolysate should be controlled below 1.5%, otherwise there are some holes on the cross section of the collagen/PVA composite fiber and the mechanical properties and crystallinity of the composite fiber are poor. The results of this research would provide a potential choice for applying collagen hydrolysate in textiles and could be a reference for selecting the proper collagen hydrolysate to obtain collagen/PVA composite fiber materials with better performances.

Feeding frequency affects feed intake and growth in juvenile pirarucu (Arapaima gigas)

ABSTRACT Pirarucu is one of the main fish species for the development of aquaculture in the Amazon. In this study, the optimal feeding frequency for juvenile pirarucu was assessed based on growth and feed efficiency. Juvenile pirarucu weighing ca. 80 g were fed once, twice, three or four times daily until apparent satiation for 63 days. Fish fed three or four times per day presented higher growth, feed intake, and fat body content than those fed once or twice per day. There was no significant difference for feed conversion ratio, and protein and energy retention rates among treatments, suggesting that increased feeding frequency did not affect feed utilization efficiency. Mean feed intake per meal was higher when fish were fed once per day, possibly causing hyperphagic behavior. Results suggest that feeding three times per day was sufficient to secure adequate feeding and growth of juvenile pirarucu.

EFFECTS OF DIETS WITH DIFFERENT PROTEIN LEVEL FOR COBIA (Rachycentron canadum) GROWTH IN CONTROLLED TANK

The feed given to cobia’s juvennile (Rachycentron canadum) still uses expensive factory-made feed to be the basis of this research. This aims of this research to examine the effect of feed formula with different protein levels on optimal growth cobia. This research method used a completely randomized design (CRD) with three treatments and three replications. The treatment in this study were different protein level commercial feed (as control/46%), and formula feed (protein P1 46% and P2 protein 48%). The parameters tested included absolute weight, daily growth rate, feed conversion ratio, protein retention, and survival rate. The data obtained were analyzed by analysis of variance and continued with the duncan test with a 95% confidence interval. The results showed that the growth of absolute weight and daily growth rates generated from each treatment were significantly different (p &lt;0.05), K (80.30 ± 11.20c g and 1.78 ± 0.25c g/day), P1 (21.87 ± 1.95a g and 0.49 ± 0.05a g/day), P2 (37.43 ± 3.29b g and 0.83 ± 0.07b g/day).

Carboxyl-functionalized covalent organic framework as a two-dimensional nanofiller for mixed-matrix ultrafiltration membranes

A new carboxyl-functionalized covalent organic framework (referred to as COF hereafter, unless otherwise noted) contains aromatic backbones and carboxyl-functionalized nanopores has been synthesized and used as a two-dimensional (2D) nanofiller in polyacrylonitrile (PAN) polymer matrix of ultrafiltration (UF) membranes. A series of mixed-matrix UF membranes with various concentrations COF ranging from 0 to 0.8 wt% have been investigated using non-solvent induced phase separation (NIPS) method. The effect of COF concentration has been evaluated on the membrane morphology, intrinsic and mechanical properties, separation performance, and fouling propensity. Increasing COF concentration from 0 to 0.8 wt% could significantly enhance the rejection rate from 3.5 to 81.9 wt% for bovine serum albumin (BSA) and 65.0–99.4 wt% for γ-globulin. Moreover, membrane hydrophilicity greatly increased, with the decrease of water contact angle from 64.4° to 45.3°. Overall, compared to the pristine PAN membrane, the mixed-matrix PAN membrane with 0.8 wt% COF demonstrated high water flux of 940 L m−2 h−1 bar−1, better protein retention rate, thermal stability, mechanical properties, and fouling resistance.

Aurantiochytriumsp. meal as DHA source in Nile tilapia diet, part I: Growth performance and body composition

This study evaluated the inclusion of Aurantiochytrium sp. (ALL-G-RICH™), a source of docosahexaenoic acid (22:6 n-3, DHA), in the diet of Nile tilapia and its effect on growth performance indexes and body composition. Fish (initial mean weight 8.35 ± 0.80 g) were fed different dietary inclusion levels of ALL-G-RICH™: 0.00, 0.05, 0.10, 0.20, and 0.40 g/kg and a control diet using cod liver oil (CLO), to provide DHA content comparable to the inclusion of 0.10 g/kg ALL-G-RICH™. Although there was no significant effect (p > 0.05) on weight gain, specific growth rate, feed conversion, protein retention rate, and proximal body composition, the inclusion of ALL-G-RICH™ in the Nile tilapia diet influenced positively the fatty acid profile in the body, resulting in a high DHA concentration. CLO-fed fish accumulated significantly more DHA compared to those fed 0.10 g/kg ALL-G-RICH™ (p < 0.05). A digestibility trial was also performed for ALL-G-RICH with 65.86 g mean-initial-weight fish. The digestibility was high for DHA (96.10%); however, it was low for palmitic acid (70.81%). The results show that the inclusion of up to 0.40 g/kg ALL-G-RICH™ can be used in Nile tilapia diets without impairing growth performance.

FARINHA DE PEIXE OBTIDA DO PROCESSAMENTO DE Rhamdia quelen: UMA FONTE PROTEICA ALTERNATIVA

O estudo de fontes de proteí­­nas alternativas é muito importante para reduzir o custo de dietas aquí­­colas. Neste estudo foi avaliada a utilização de resí­­duos do processamento de jundiá (Rhamdia quelen) na dieta de juvenis desta espécie. Deste modo, foi utilizado sistema de recirculação com 16 tanques de polipropileno (280 L), cada um com 50 peixes (peso inicial = 5,5 ± 0,09 g). Foram testadas quatro dietas (37% de proteí­­na bruta e 3.200 kcal-1 kg de energia digestí­­vel): dieta controle, composta por farinha de carne e ossos suí­­na, substituí­­da por farinha de peixe, composta por peixe inteiro (jundiá), farinha de carcaças de jundiá com ví­­sceras e dieta com farinha de carcaças de jundiá sem ví­­sceras. Foi avaliado, o peso final, fator de condição, taxa de crescimento especí­­fico, taxa de conversão alimentar, ganho de peso diário e taxa de retenção de proteí­­na. Observou-se maior peso final (50,5 g), taxa de crescimento especí­­fico (3,9% dia-1), conversão alimentar (1,3:1), deposição de proteí­­na corporal (6,3 g) para os peixes alimentados com as dietas compostas por farinha de carcaça de jundiás com ví­­sceras. A incorporação de farinha de resí­­duos do processamento de jundiás na dieta é viável para o crescimento dos peixes.

Replacement of fishmeal by spirulina Arthrospira platensis affects growth, immune related-gene expression in gibel carp (Carassius auratus gibelio var. CAS III), and its challenge against Aeromonas hydrophila infection

The present study examined the effect of dietary spirulina, Arthrospira platensis on growth performance, blood physiological indices, immune-related gene expressions and resistance of juvenile gibel carp against Aeromonas hydrophila infection. Four isonitrogenous (360 g kg−1) and isolipidic (90 g kg−1) diets were formulated with containing different levels of spirulina powder of 0 g (SP0, the control diet), 3.38 g (SP3.38), 6.76 g (SP6.76) and 13.52 g (SP13.52) per 100 g diet to replace 0%, 25%, 50% and 100% of fishmeal protein, respectively. And each diet was randomly assigned to triplicate tanks (150-L capacity per each) and each tank was stocked with 22 fish (15.37 ± 0.06 g). Fish were fed one of the tested diets up to satiation twice a day for 46 days. A challenge test was carried out after the feeding trial by injecting Aeromonas hydrophila intraperitoneally for 7 days. The results showed that fish growth, feeding rate in groups SP3.38 and SP6.76 were significantly higher than those of groups SP0 and SP13.52 (P < 0.05). Feed efficiency and protein retention rate had no significant difference among all tested groups. Plasma superoxide dismutase and phagocyte activity of blood leukocytes significantly increased in the spirulina-fed fish groups at 12-h post the bacterial challenge (P < 0.05). Both pre and post challenge test, plasma lysozyme activities in spirulina-fed groups were significantly higher than that in the control group (P < 0.05). Plasma malondialdehyde got the lowest value in the SP13.52 group before and after the challenge test. The transcriptional levels of TLR2 (Toll like receptor 2), myeloid differentiation factor 88 (MyD88), Toll/IL-1 receptor domain-containing adaptor protein (TIRAP), interleukin-1β (IL-1β) and tumor necrosis factor-α1 (TNF-α1) in spleen and kidney significantly increased post the bacterial challenge compared to the pre challenge. And the relative expressions of the immune-related genes of spirulina-fed fish groups were higher than those of the control group before and after the challenge test. The 7-day cumulative survival rate after the bacterial challenge was highest in the SP3.38 group (P < 0.05). The present results indicated that low dietary inclusion of spirulina significantly enhanced the immune response of gibel carp partly through TLR2 pathway and 3.38% of dietary spirulina was recommended for the juveniles based on the growth and immune response.

Digestible Protein Requirement of Pirarucu Juveniles (Arapaima gigas) Reared in Outdoor Aquaculture

Pirarucu (Arapaima gigas) is a fast-growing, carnivorous species reared commercially in Amazonian countries as Brazil. Lack of a nutritionally balanced and affordable diet is a major constraint in pirarucu aquaculture, and our investigation sought to estimate the dietary protein requirement for this species. Four diets were formulated to contain increasing concentrations of digestible protein (32, 35, 38, and 41%) and fed to triplicate groups of juvenile pirarucu of around 2 kg for 18 weeks. As result, pirarucu showed no differences in feed intake, survival, or fillet yield. However, regression analysis revealed that weight gain (WG) values showed a general increasing trend with increasing dietary digestible protein (DP) level up to 36.7%. In addition, feed conversion rates were also improved with increase in dietary DP up to 36.4%. Fish fed diets containing 32 and 41% had poor feed conversion rates. Thel protein retention rate (PRR) and protein efficiency index (PER) decreased as levels of DP increased. The optimal dietary protein content for juvenile pirarucu between 1.98 and 4 kg of BW is about 36% of digestible protein on diet.

Waste from the biscuit and noodle industries in Nile tilapia diets

The objectives of this work were to determine the apparent digestibility coefficients (ADC) of dry matter (DM), crude protein (CP) and gross energy (GE) of coconut biscuit residues (CBR), sweet biscuits (SBR) and noodles (NR) for Nile tilapia and evaluate the performance of fingerlings fed with diets containing the residues with the highest nutritional value. In the digestibility study, 72 juveniles (with an average weight of 70.5 ± 2.7 g) were organized in a completely randomized design with three treatments and three replications (12 fish per replication). ADC was determined using an indirect method in which 0.10% chromium oxide (Cr2O3) acted as an indicator. To evaluate performance, 225 fingerlings (with an average weight of 3.4 ± 0.5 g) were distributed across 15 tanks (150 L), creating a completely randomized design with five treatments and three replications. The test diets contained 0, 4, 8, 12 or 16% CBR. ADCDM, ADCCP and ADCGE for each of the different residues were, respectively: 85, 88 and 86% for CBR; 32, 51 and 46% for SBR; 24, 31 and 26% for NR. The inclusion of CBR significantly affected final weight of the fish, specific growth rate and protein retention rate, as well as the carcass composition values for dry matter, mineral matter, gross energy and ethereal extract. CBR presents better digestibility than the other tested residues and it can be used as a substitute for maize meal in quantities up to 11.62%, thus improving fish performance.

Digestibility, protein retention rate and ammonia excretion in juvenile fat snook (Centropomus parallelus) fed with different protein levels

ABSTRACT: The aim of this study was to determine the level of dietary crude protein (CP) (480, 400, 440, 520 and 560g kg-1) in rations for juvenile II fat snook (Centropomus parallelus) that best promotes protein absorption and lower excretion of nitrogenous products. Three experiments were conducted: the first assessed the protein retention rate; the second evaluated ammonia excretion; and the third determined the best digestibility coefficient. The estimated protein retention rate showed a positive quadratic response to dietary CP with maximum retention at the 510.20g kg-1 protein level, and increasing levels of protein resulted in a greater total ammonia excretion rate in water. The mean apparent protein digestibility coefficient values increased with increasing levels of dietary protein up to 520g kg-1, where they stabilized. As determined by regression, the level of dietary CP that promotes the best digestibility was 495.62g kg-1.

Effect of salinity on performance and body composition of Pacific white shrimp juveniles reared in a super-intensive system

The objective of this study was to evaluate the effect of salinity on the culture water quality, performance and body composition of Litopenaeus vannamei juveniles (1.16±0.30 g) reared for 36 days in a super-intensive system without water exchange at salinities of 4, 16 and 32‰. Groups of 200 animals (140/m2) were stocked, with three replicates, in nine fiber-cement tanks (1.11 × 1.29 × 0.70 m) with a useful volume of 400 L. Physical and chemical parameters of water, such as temperature and dissolved oxygen before and after midday, pH, alkalinity, total suspended solids, total ammonium nitrogen, nitrite, nitrate, and phosphate, were monitored. Performance parameters like survival, weight gain, specific growth rate, feed conversion ratio and protein retention rate, were also evaluated. The proximate composition of the juveniles was analyzed through the moisture, protein, lipid and ash contents. The physical and chemical parameters of the water were influenced by the treatments. The increased salinity produced a significant increase in the alkalinity and the concentrations of total suspended solids, nitrite and phosphate. Of the parameters that were examined to evaluate the performance and proximate composition of the shrimp, only survival, protein retention rate and body lipid content were significantly influenced. The highest values were found at a salinity of 32‰. However, the analysis of the proximate composition of the bioflocs showed that the moisture, protein and lipid contents increased as the salinity decreased. Growth, use of feed and survival of L. vannameijuveniles reared in a super-intensive system without water exchange is positively influenced by an increase of salinity from 4 to 32‰.