Fed Soybean Meal-based Diets Research Articles

Dietary glycine supplementation enhances syntheses of creatine and glutathione by tissues of hybrid striped bass (Morone saxatilis ♀ × Morone chrysops ♂) fed soybean meal-based diets

BackgroundWe recently reported that supplementing glycine to soybean meal-based diets is necessary for the optimum growth of 5- to 40-g (Phase-I) and 110- to 240-g (Phase-II) hybrid striped bass (HSB), as well as their intestinal health. Although glycine serves as an essential substrate for syntheses of creatine and glutathione (GSH) in mammals (e.g., pigs), little is known about these metabolic pathways or their nutritional regulation in fish. This study tested the hypothesis that glycine supplementation enhances the activities of creatine- and GSH-forming enzymes as well as creatine and GSH availabilities in tissues of hybrid striped bass (HSB; Morone saxatilis♀ × Morone chrysops♂).MethodsPhase-I and Phase-II HSB were fed a soybean meal-based diet supplemented with 0%, 1%, or 2% glycine for 8 weeks. At the end of the 56-d feeding, tissues (liver, intestine, skeletal muscle, kidneys, and pancreas) were collected for biochemical analyses.ResultsIn contrast to terrestrial mammals and birds, creatine synthesis occurred primarily in skeletal muscle from all HSB. The liver was most active in GSH synthesis among the HSB tissues studied. In Phase-I HSB, supplementation with 1% or 2% glycine increased (P < 0.05) concentrations of intramuscular creatine (15%–19%) and hepatic GSH (8%–11%), while reducing (P < 0.05) hepatic GSH sulfide (GSSG)/GSH ratios by 14%–15%, compared with the 0-glycine group; there were no differences (P > 0.05) in these variables between the 1% and 2% glycine groups. In Phase-II HSB, supplementation with 1% and 2% glycine increased (P < 0.05) concentrations of creatine and GSH in the muscle (15%–27%) and liver (11%–20%) in a dose-dependent manner, with reduced ratios of hepatic GSSG/GSH in the 1% or 2% glycine group. In all HSB, supplementation with 1% and 2% glycine dose-dependently increased (P < 0.05) activities of intramuscular arginine:glycine amidinotransferase (22%–41%) and hepatic γ-glutamylcysteine synthetase (17%–37%), with elevated activities of intramuscular guanidinoacetate methyltransferase and hepatic GSH synthetase and GSH reductase in the 1% or 2% glycine group. Glycine supplementation also increased (P < 0.05) concentrations of creatine and activities of its synthetic enzymes in tail kidneys and pancreas, and concentrations of GSH and activities of its synthetic enzymes in the proximal intestine.ConclusionsSkeletal muscle and liver are the major organs for creatine and GSH syntheses in HSB, respectively. Dietary glycine intake regulates creatine and GSH syntheses by both Phase-I and Phase-II HSB in a tissue-specific manner. Based on the metabolic data, glycine is a conditionally essential amino acid for the growing fish.

Effect of yeast species and processing on intestinal microbiota of Atlantic salmon (Salmo salar) fed soybean meal-based diets in seawater

BackgroundYeasts are gaining attention as alternative ingredients in aquafeeds. However, the impact of yeast inclusion on modulation of intestinal microbiota of fish fed plant-based ingredients is limited. Thus, the present study investigates the effects of yeast and processing on composition, diversity and predicted metabolic capacity of gut microbiota of Atlantic salmon smolt fed soybean meal (SBM)-based diet. Two yeasts, Cyberlindnera jadinii (CJ) and Wickerhamomyces anomalus (WA), were produced in-house and processed by direct heat-inactivation with spray-drying (ICJ and IWA) or autolyzed at 50 °C for 16 h, followed by spray-drying (ACJ and AWA). In a 42-day feeding experiment, fish were fed one of six diets: a fishmeal (FM)-based diet, a challenging diet with 30% SBM and four other diets containing 30% SBM and 10% of each of the four yeast products (i.e., ICJ, ACJ, IWA and AWA). Microbial profiling of digesta samples was conducted using 16S rRNA gene sequencing, and the predicted metabolic capacities of gut microbiota were determined using genome-scale metabolic models.ResultsThe microbial composition and predicted metabolic capacity of gut microbiota differed between fish fed FM diet and those fed SBM diet. The digesta of fish fed SBM diet was dominated by members of lactic acid bacteria, which was similar to microbial composition in the digesta of fish fed the inactivated yeasts (ICJ and IWA diets). Inclusion of autolyzed yeasts (ACJ and AWA diets) reduced the richness and diversity of gut microbiota in fish. The gut microbiota of fish fed ACJ diet was dominated by the genus Pediococcus and showed a predicted increase in mucin O-glycan degradation compared with the other diets. The gut microbiota of fish fed AWA diet was highly dominated by the family Bacillaceae.ConclusionsThe present study showed that dietary inclusion of FM and SBM differentially modulate the composition and predicted metabolic capacity of gut microbiota of fish. The inclusion of inactivated yeasts did not alter the modulation caused by SBM-based diet. Fish fed ACJ diet increased relative abundance of Pediococcus, and mucin O-glycan degradation pathway compared with the other diets.

Dietary glycine supplementation enhances the growth performance of hybrid striped bass (Morone saxatilis ♀× Morone chrysops ♂) fed soybean meal-based diets.

This study was conducted to test the hypothesis that supplementing 1% and 2% glycine to soybean meal (SBM)-based diets can improve the growth performance of juvenile hybrid striped bass (HSB). The basal diets contained 15% fishmeal and 58% SBM (DM basis). Alanine was used as the isonitrogenous control in different diets. All diets contained 44% crude protein and 10% lipids (DM basis). There were four tanks (15 fish per tank) per dietary group, with the mean of the initial body weight (BW) of fish being 5.3 g. Fish were fed to apparent satiation twice daily, and their BW was recorded every 2 wk. The trial lasted for 8 wk. Results indicated that the BW, weight gain, protein efficiency ratio, and retention of dietary lipids in fish were enhanced (P < 0.05) by dietary supplementation with 1% or 2% glycine. In addition, dietary supplementation with glycine did not affect (P > 0.05) the feed intake of fish but increased (P < 0.05) the retention of dietary nitrogen, most amino acids, and phosphorus in the body, compared to the 0% glycine group. Dietary supplementation with 1% and 2% glycine dose-dependently augmented (P < 0.05) the villus height of the proximal intestine and reduced the submucosal thickness of the gut, while preventing submucosal and lamina propria hemorrhages. Compared with the 0% glycine group, dietary supplementation with 1% or 2% glycine decreased (P < 0.05) the proportion of skeletal-muscle fibers with diameters of 40 to 60 µm but increased (P < 0.05) the proportion of skeletal-muscle fibers with diameters of 80 to 100 µm and > 100 µm. Collectively, these findings indicate that glycine in SBM-based diets is inadequate for maximum growth of juvenile HSB and that dietary supplementation with 1% or 2% glycine is required to improve their weight gain and feed efficiency. Glycine is a conditionally essential amino acid for this fish.

Dietary glycine supplementation improves the growth performance of 110- to 240-g (phase II) hybrid striped bass (Morone saxatilis ♀× Morone chrysops ♂) fed soybean meal-based diets.

We recently reported that supplementing glycine to soybean meal (SBM)-based diets is necessary for optimum growth of 5- to 40-g (phase I) hybrid striped bass (HSB). The present study tested the hypothesis that supplementing glycine to SBM-based diets may enhance the growth of 110- to 240-g (phase II) HSB. HSB (the initial body weight of approximately 110 g) were fed an SBM (58%)-based diet supplemented with 0%, 1%, or 2% of glycine, with l-alanine serving as the isonitrogenous control. There were four tanks per dietary group, with four fish per tank. The fish were fed their respective diets to apparent satiation twice daily. The feed intake and body weight of fish were recorded daily and every 2 wk, respectively. At the end of the 56-d feeding trial, plasma and tissue samples were collected to determine amino acid concentrations and histological alterations, and tissues were used to measure the oxidation of l-glutamate, l-glutamine, l-aspartate, and glycine. Results showed that dietary supplementation with 1% and 2% glycine dose-dependently increased (P < 0.05) the concentration of glycine in the plasma of HSB by 48% and 99%, respectively. Compared with the 0%-glycine group, dietary supplementation with 1% glycine did not affect (P > 0.05) the feed intake of HSB but increased (P < 0.05) their final body weight, weight gain, and gain:feed ratio during the whole period by 13%, 29%, and 21%, respectively. Compared with the 1% glycine group, dietary supplementation with 2% glycine increased (P < 0.05) the feed intake, final body weight, and weight gain of HSB by 13%, 7%, and 14%, respectively. Compared with the 0%-glycine group, fish fed with the 1%-glycine and 2%-glycine diets had a greater (P < 0.05) villus height in the proximal intestine, when compared with the 0%-glycine group. Collectively, these results indicated that SBM-based diets did not provide sufficient glycine for phase II HSB (110 to 240 g) and that dietary glycine supplementation is essential for their optimum growth and intestinal structure.

Effects of Yeast Species and Processing on Intestinal Health and Transcriptomic Profiles of Atlantic Salmon (Salmo salar) Fed Soybean Meal-Based Diets in Seawater.

The objective of the current study was to examine the effects of yeasts on intestinal health and transcriptomic profiles from the distal intestine and spleen tissue of Atlantic salmon fed SBM-based diets in seawater. Cyberlindnera jadinii (CJ) and Wickerhamomyces anomalus (WA) yeasts were heat-inactivated with spray-drying (ICJ and IWA) or autolyzed at 50 °C for 16 h (ACJ and AWA), followed by spray-drying. Six diets were formulated, one based on fishmeal (FM), a challenging diet with 30% soybean meal (SBM) and four other diets containing 30% SBM and 10% of each of the four yeast fractions (i.e., ICJ, ACJ, IWA and AWA). The inclusion of CJ yeasts reduced the loss of enterocyte supranuclear vacuolization and reduced the population of CD8α labeled cells present in the lamina propria of fish fed the SBM diet. The CJ yeasts controlled the inflammatory responses of fish fed SBM through up-regulation of pathways related to wound healing and taurine metabolism. The WA yeasts dampened the inflammatory profile of fish fed SBM through down-regulation of pathways related to toll-like receptor signaling, C-lectin receptor, cytokine receptor and signal transduction. This study suggests that the yeast species, Cyberlindnera jadinii and Wickerhamomyces anomalus are novel high-quality protein sources with health-beneficial effects in terms of reducing inflammation associated with feeding plant-based diets to Atlantic salmon.

Effects of Dietary Soybean (Glycine max) on Growth Performance, Haematology and Serum Biochemistry of African Carp (Labeo Cubie Ruppell 1832)

The effects of dietary replacements of fish meal with soybean meal on growth performance, heamatology and serum biochemistry in juvenile Labeo cubie were evaluated. Four hundred and fifty (450) apparently healthy juvenile Laboe cubie were distributed into one of fifteen 1000 L tanks divided into five groups and fed any of diets A (0% soybean meal); B (30% soybean meal); C (40% soybean meal); D (45% soybean meal) and diet E (75% soybean meal) for 56 days. At set time points day 7, 14, 28 and day 56, five fish were randomly selected per tank for growth assessments, heamatology and serum biochemical evaluations. Growth performance indices decreased significantly (p &lt; 0.05) along the gradient of soybean meal inclusion and the duration of feeding. The erythrocytes count increased significantly (p &lt; 0.05) at day 14 in fish fed soybean meal diets and decreased significantly (p &lt; 0.05) beginning at day 28 in fish fed soybean meal-based diets. The haematocrit of fish fed diets D and E were significantly (p &lt; 0.05) lower at day 28 compared to day 56. There were no significant variations in haemoglobin concentration and the leucocytes counts (p &gt; 0.05). The proteins, blood glucose and the transaminases increased significantly (p &lt; 0.05) along gradient of dietary inclusion and duration of feeding in the first 28 days while creatinine kinase activity, blood urea nitrogen and uric acid concentration remained significantly elevated (p &lt; 0.05) in fish fed the soybean meal-based diets. The results of the study show juvenile L. cubie may tolerate up to 40% dietary inclusion of soybean meal as replacement for fish meal.

The protective role of daidzein in intestinal health of turbot (Scophthalmus maximus L.) fed soybean meal-based diets

Soybean meal-induced enteropathy (SBMIE) is prevalent in aquaculture. The aim of this study is to evaluate the role of daidzein on SBMIE of juvenile turbot (Scophthalmus maximus L.) by feeding with fish meal diet (FM), soybean meal diet (SBM, 40% fish meal protein in FM replaced by soybean meal protein) and daidzein diet (DAID, 40 mg/kg daidzein supplemented to SBM) for 12 weeks. We found that daidzein supplementation elevated the gene expression of anti-inflammatory cytokine TGF-β, decreased gene expression of pro-inflammatory cytokines TNF-α and signal molecules p38, JNK and NF-κB. SBM up-regulated the genes expression related to oxidative stress and apoptosis, but dietary daidzein restored it to the similar level with that in FM group. Moreover, dietary daidzein up-regulated gene expression of tight junction protein, and modified the intestinal microbial profiles with boosted relative abundance of phylum Proteobacteria and Deinococcus–Thermus, genera Sphingomonas and Thermus, species Lactococcus lactis, and decreased abundance of some potential pathogenic bacteria. In conclusion, dietary daidzein could ameliorate SBM-induced intestinal inflammatory response, oxidative stress, mucosal barrier injury and microbiota community disorder of turbot. Moreover, p38, JNK and NF-κB signaling might be involved in the anti-inflammatory process of daidzein, and daidzein itself might act as an antioxidant to resist SBM-induced oxidative damage.

Lecithin‐containing bioemulsifier boosts growth performance, feed digestion and absorption and immune response of adult Nile tilapia ( Oreochromis niloticus )

The present study evaluated the effects of a commercial soy lecithin-containing bioemulsifier Lysomax® on growth performance, feed utilization, haematology, immune response and gut histology of adult Nile tilapia (Oreochromis niloticus) fed soybean meal-based diets, containing plant oil as a lipid source. This emulsifier was incorporated into four isonitrogenous (30% cp), isocaloric (17.5 MJ/kg) test diets, at 0 (control), 0.3, 0.6 and 0.9 g/kg feed. The diets were fed to triplicate groups of adult Nile tilapia, reared in a closed recirculating indoor system, at a daily rate of 3% of fish live weight, twice a day for 60 days. Growth rates, feed utilization efficiency, digestive enzymes activities, blood parameters, liver function enzymes and immunological responses were all boosted (p < .05) with increasing supplemental Lysomax up to 0.3 g/kg diet, followed by a significant retardation (p < .05) at 0.6 and 0.9 levels. Muscle n-6 and n-3 polyunsaturated fatty acids (PUFA) and n3/n6 ratio were also increased with increasing Lysomax up to 0.3 level and then levelled off with further increase in dietary Lysomax. The highest length and width of the intestinal microvilli and goblet cell counts were also found in the fish fed on 0.3 g Lysomax/kg diet. However, the quadratic regression analyses of the obtained results indicated that the maximum performance occurred at about 0.45 g/kg of dietary Lysomax. These results suggest that lecithin-containing bioemulsifier Lysomax® can play a significant role in feed digestion and absorption and improving fish performance and innate immune response. About 0.45 g/kg diet would be sufficient for best performance and health status of farmed Nile tilapia.

Nutritional programming effects on growth and reproduction of broodstock and embryonic development of progeny in yellow perch (Perca flavescens) fed soybean meal-based diets

The objective of this research was to determine if growth performance of yellow perch (Perca flavescens) could be enhanced through nutritional programming when fed soybean meal-based (SBM) diets as their first feed. It was hypothesized that juvenile yellow perch could be nutritionally programmed by being fed SBM-based diets as their first formulated feed, and that this would result in improved growth performance when reintroduced to this diet later in life. It is assumed that nutritionally programmed fish transitioned back to fish meal (FM)-based diets during gametogenesis would eliminate reproductive effects from the SBM-based diets, such as reduced fecundity, egg quality or fertilization rate.The experimental design was carried out over four phases. In Phase 1, juvenile yellow perch were divided into four dietary treatments: 1) FM control, 2) wheat gluten meal (WG) and 3) and 4) two soybean meal (SBM-A/SBM-B) varieties, all fed to fish in triplicate. Plant proteins replaced 75% of the fish meal protein in the diet formulations, and diets were fed to juveniles for 2 months. In Phase 2, fish were combined in a “common garden” design, and all fed the FM diet for 9 months. In Phase 3, all fish were transitioned to the SBM-A diet for 7 months. Mean individual weights of fish and survival were measured at the beginning and end of each phase. Growth performance was calculated as weight gain (%) and specific growth rate (SGR, %/day. In Phase 4, fish were fed the FM diet over winter (6 months) when gametogenesis occurs and somatic growth was minimal. When females were ready to ovulate, they were manually stripped of eggs and fertilized with pond-raised males. Mean egg weight, total number of eggs, fecundity, gonadosomatic index (GSI), and fertilization rate were all calculated to determine reproductive quality.Results from phase 3 show that fish nutritionally programmed with SBM-A, had a higher weight gain percent when returned to SBM than fish from the other three diets, though not significant. Specifically, weight gain of SBM-A fed fish was 150 ± 31%, whereas other groups were 114 ± 24% (FM), 110 ± 26% (WG) and 118 ± 15% (SBM-B). Female reproductive quality was not affected by diet and results showed no significant differences between any of the parameters examined. However, growth during phase 4 was correlated with time to ovulation, increased GSI and mean egg weight.

Effect of protease and phytase supplementation on growth performance and nutrient digestibility of rainbow trout (Oncorhynchus mykiss, Walbaum) fed soybean meal-based diets

ABSTRACTAn experiment was conducted to evaluate effects on growth, body composition and nutrient digestibility of addition protease and phytase to soybean meal-based diet in rainbow trout. Seven soybean meal-based diets were prepared by adding protease, phytase and mixture of both enzymes at two different levels (1 and 2 g kg−1) to a base diet without enzymes. Mixed enzymes (1, 2 g kg−1) were prepared by adding protease and phytase at the same doses (0.5 + 0.5 and 1 + 1 g kg−1). Diets consisted of 31% fish meal and 44% dehulled hexane extracted soybean meal. At the start of the experiment, 45 rainbow trout (initial mean body weight 88 g) were stocked into each of 21 fibre tanks. After 90 days, there were no significant differences on the growth, feed conversion ratio, digestibility of protein and lipid among the groups. Results of this study showed that the addition of protease or phytase as mix to soybean meal-based diet could not increase growth and nutrient digestibility in trout.

Histological and micro-/macro-morphological evaluation of intestine in sharpsnout seabream (Diplodus puntazzo) fed soybean meal-based diets added with MOS and inulin as prebiotics

The effects of mannanoligosaccharides (MOS) and inulin (INU) inclusion (8 g kg−1) in a soybean meal (SBM)-containing diet on histology, macro- and micromorphology of proximal and distal intestine of sharpsnout seabream (Diplodus puntazzo) were evaluated. 144 sharpsnout seabream (100 g average initial body weight) were fed with 4 isolipidic and isoproteic diets. At the end of the experimental period (114 days), four fish per diet were randomly sampled. The partial substitution of fish meal (FM) with SBM affected the intestine histology and macromorphology of sharpsnout seabream and modified the enterocyte parameters. The addition of prebiotics has not produced positive effects, leading in some cases to a worsening, especially for INU diet that markedly altered the intestine histology. The micromorphological values were in both proximal and distal intestines significantly affected by the diet: in proximal tract, the nucleus was closer to the apex of the enterocyte in soy-fed fish (SBM, IMU, MOS diets), while fish fed with MOS diet showed the lowest value of enterocyte height, significantly different from the FM diet. In distal tract of intestine, fish fed with FM diet showed the highest value for all considered parameters, while MOS diet resulted in the lowest enterocyte height and supranucleus height among the four diets. SBM-containing diets (SBM, IMU, MOS) resulted in lower values than FM diet for the features of enterocyte nucleus. Microvilli height was not affected by the diet in both proximal and distal tracts. In conclusion in this study, the partial substitution of FM with SBM (40 % on protein basis) induced inflammatory reaction of the gut in sharpsnout seabream, evidenced by histological analysis and changes in morphometric characters of villi and enterocytes, not amended by the addition of MOS and even worsened in the case of inulin.

Dietary taurine enhances growth and feed utilization in larval Nile tilapia (Oreochromis niloticus) fed soybean meal-based diets

This study was conducted to evaluate the effects of dietary taurine on growth performance and feed utilization of Nile tilapia (Oreochromis niloticus) larvae. Four plant protein-based, isonitrogenous (400 g kg−1 protein), isoenergetic (19 MJ kg−1) diets supplemented with four taurine concentrations (0.0, 5.0, 10.0 and 15.0 g kg−1; designated as T0, T0.5, T1 and T1.5, respectively) were prepared. The diets were fed to triplicate groups of fish larvae (0.024 g average body weight), to apparent satiation, three times per day for 60 days. Larval growth rates and feed utilization efficiency were significantly improved with increasing supplemental taurine up to 10 g kg−1 and decreased with further taurine supplementation. The quadratic regression analyses indicated that the maximum larval performance occurred at about 9.7 g kg−1 of total dietary taurine. Fish survival was significantly lower at 15 g kg−1 dietary taurine than at other taurine levels. Body protein significantly increased, while body moisture and ash decreased, with increasing dietary taurine up to 10 g kg−1 and decreased with further taurine supplementation to 15 g kg−1. Body lipid was not significantly affected by dietary taurine concentration. A number of body amino acids (tryptophan, arginine, histidine, leucine, isoleucine, valine, alanine, glycine, threonine and taurine) significantly increased with increasing supplemental taurine up to 10 g kg−1 and then decreased with further increase in dietary taurine levels. The rest of body amino acids were not significantly affected by dietary taurine. The present results suggest that about 9.7 g kg−1 dietary taurine is required for optimum performance of Nile tilapia larvae fed soybean meal-based diets.

Dietary taurine improves reproductive performance of Nile tilapia (Oreochromis niloticus) broodstock

This study was conducted to evaluate the effects of supplemental taurine on reproductive performance of Nile tilapia (Oreochromis niloticus) broodstock fed soybean meal-based diets. Four isonitrogenous (350 g kg−1 protein), isocaloric (18 MJ kg−1) diets were formulated to contain 0, 5, 10 and 15 g kg−1 taurine. The diets were fed to triplicate groups of juvenile Nile tilapia (10–15 g average body weight) at a female: male ratio of 3 : 1, to apparent satiation, three times per day for 130 days. The size at first maturation decreased with increasing dietary taurine to 10 g kg−1 and levelled off with further taurine supplementation. The time to first spawning was also significantly shorter at 10 g kg−1 taurine level. Spawning performances, including spawning frequencies, total number of spawnings per tank, number of spawnings per female and absolute fecundity, were all significantly improved with increasing dietary taurine up to 10 g kg−1. However, the quadratic regression analyses indicated that the maximum spawning performance occurred at 8 g kg−1 of supplemental taurine. Eggs produced from broodstock fed 10 g kg−1 taurine exhibited significantly higher hatchability and required shorter time for hatching and yolk-sac absorption and also resulted in higher larval weight than at other dietary taurine levels. The highest egg protein, total amino acids and taurine were also obtained at 10 g kg−1 taurine. These results suggest that 8 g kg−1 dietary taurine is required for optimum reproductive outputs of Nile tilapia broodstock.

Effects of the Dietary Microbial Phytase Supplementation on Bioavailability of Phosphorus in Juvenile Olive Flounder Paralichthys olivaceus Fed Soybean Meal based Diets

An 8 weeks feeding trial was carried out to evaluate the effects of dietary microbial phytase (P) supplementation on nutrient digestibility, and body composition in juvenile olive flounder Paralichthys olivaceus fed soybean meal-based diets. Seven experimental diets were formulated to be isonitrogenous and isocaloric to contain 50.0% crude protein (CP) and 16.7 kJ of available energy/g with or without dietary phytase supplementation. White fish meal (FM) provided 92.4% of the total protein in the basal diet (S0), in the other 6 diets, 30% or 40% FM protein was replaced by soybean meal: 70% FM + 30% soybean meal (S30); 70% FM + 30% SM + 1000 U phytase/kg diet (S30P1000); 70% FM + 30% SM + 2000 U phytase/kg diet (S30P2000); 60% FM + 40% SM (S40); 60% FM + 40% SM + 1000 U phytase/kg diet (S40P1000); and 60% FM + 40% SM + 2000 U phytase/kg diet (S40P2000). After two weeks of the conditioning period, triplicate groups of 25 fish initially averaging 6.15 ± 0.04 g (mean ± S.D.) were randomly distributed into the aquarium and were fed one of the experimental diets for 8 weeks. After feeding trial, supplementation of phytase significantly improved the apparent digestibility coefficients of phosphorus in flounder diets ( P<0.05) containing 30% and 40% soybean meal regardless the levels. However, phytase had no significant influence on growth performance and whole body composition of fish. Based on the experimental results, we conclude that dietary supplementation of phytase could improve the apparent digestibility coefficient of phosphorus in olive flounder.

Effect of soybean diet: Growth and conversion efficiencies of fingerling of stinging cat fish, Heteropneustes fossilis (Bloch)

Replacement of 15% protein from soybean meal in Diet II was feasible for the stinging cat fish, Heteropneustes fossilis and no significant differences in growth parameters were found in fish fed soybean meal-based diets compared to those fed control diet (Diet I). Live weight gain percent (165%) obtained in fish fed soybean meal based diet was not significantly different to that achieved (171%) in fish fed Diet I. Specific growth rate percent, SGR (2.79%), feed conversion ratio FCR (1.40) and protein efficiency ratio PER (1.79) recorded in fish fed Diet II were also more less comparable to those fed control diet. Mortality was not recorded in the period of the feeding trial. Body composition of the fish fed soybean meal based diet (Diet II) was also comparable to that fed control diet. Significantly higher fat content was noted in fish fed Diet II. However, the protein contents were not changed in fish fed Diet I and II. Similarly, no significant differences (P>0.05) in protein productive value were noted between the two groups. However, ash content differed significantly (P<0.05) in fish fed Diet I and II. Although soybean meal-based diet depressed growth and feed conversion efficiencies of the fish to some extent, inclusion of soybean meal was found to be cost-effective alternative to fish meal.

Effects of dietary cholesterol on antioxidant capacity, non-specific immune response, and resistance to Aeromonas hydrophila in rainbow trout (Oncorhynchus mykiss) fed soybean meal-based diets

This study evaluated the effects of dietary cholesterol on antioxidant capacity, non-specific immune response and resistance to Aeromonas hydrophila in rainbow trout (Oncorhynchus mykiss) fed soybean meal-based diets. Fish were fed diets supplemented with graded cholesterol levels (0 [control], 0.3, 0.6, 0.9, 1.2, and 1.5%) for nine weeks. The fish were then challenged by A. hydrophila and their survival rate recorded for the next week. Dietary cholesterol supplementation generally increased the serum and hepatic superoxide dismutase (SOD), glutathione-peroxidase (GSH-Px), catalase (CAT), and total antioxidant capacity (TAC) activities, but decreased the serum and hepatic malondialdehyde (MDA) contents. Further, the hepatic CAT and serum SOD, CAT, and TAC activities were significantly higher in fish fed diets supplemented with 0.9 or 1.2% cholesterol compared to those fed the control diet, whereas the serum and hepatic MDA contents were significantly lower. The respiratory burst activity, alternative complement activity, and hepatic lysozyme activity increased steadily when the supplemental cholesterol was increased by up to 1.2% and then declined with further addition. The serum lysozyme activity and phagocytic activity increased steadily with increasing dietary supplemental cholesterol level up to 0.9% and then declined with further addition. Dietary cholesterol supplementation generally enhanced the protection against A. hydrophila infection, and fish fed diets supplemented with 0.9 or 1.2% cholesterol exhibited the highest post-challenge survival rate. The results indicated that cholesterol may be under-supplied in rainbow trout fed soybean meal-based diets, and dietary cholesterol supplementation (0.9–1.2%) contributed to improved immune response and disease resistance of rainbow trout against A. hydrophila.

Effects of 11-ketotestosterone and fishmeal in the feed on growth of juvenile tilapia ( Oreochromis mossambicus)

The effects of 11-ketotestosterone (11KT) and dietary fishmeal on growth of tilapia ( Oreochromis mossambicus) were examined. Juvenile tilapia, weighing about 8 g, were reared for 50 days with isonitrogenous and isocaloric diets containing fishmeal or all plant proteins, each with or without supplementation of 11KT. Fish fed fishmeal-based (FM) diets grew significantly faster than those fed soybean meal-based (SM) diets. Addition of 11KT (10 mg/kg) to the FM diet significantly augmented growth, whereas no significant effect of 11KT was observed in fish fed SM diet. In accord with the accelerated growth, specific growth rates of fish fed FM diets were significantly greater than those of fish fed SM diets, although addition of 11KT to FM or SM diet had no effect on this parameter. Males showed significantly higher plasma levels of insulin-like growth factor-I (IGF-I) than did females; however, there was no consistent effect of fishmeal or 11KT on plasma IGF-I levels within each sex. Plasma levels of 11KT were significantly higher in males than in females. In males, plasma 11KT levels were significantly higher in fish fed FM diets than in those fed SM diet. No significant effect of fishmeal or 11KT was observed on plasma levels of 11KT or 17β-estradiol (E 2) in females. Low but significant levels of vitellogenin (Vg) were found in male plasma. Plasma Vg levels were significantly lower in fish fed SM diets than in fish fed FM diets in both males and females. These results indicate that addition of 11KT to the fishmeal-based diet stimulated growth, minimally affecting plasma levels of IGF-I, 11KT, E 2 and Vg. The absence of effect of 11KT in fish fed the soybean meal-based diet may indicate that the estrogenic activities or some components in the SM diet are likely to interfere with the growth-promoting effects of 11KT.

Dietary microbial phytase increased the phosphorus digestibility in juvenile Korean rockfish Sebastes schlegeli fed diets containing soybean meal

This study was conducted to evaluate the effects of dietary microbial phytase supplementation on nutrient digestibility, growth performance and body composition in juvenile Korean rockfish fed soybean meal-based diets. Nine experimental diets were formulated to be isonitrogenous and isocaloric to contain 48.6% crude protein (CP) and 15.9 kJ of available energy/g with or without dietary phytase (Natuphos-5000™, BASF, NJ, USA) supplementation. White fish meal (FM) provided 89.1% of the total protein in the basal diet (S 0), in the other eight diets, 30 or 40% FM protein was replaced by soybean meal: 70% FM+30% soybean meal (S 30); 70% FM+30% 1000 U phytase pretreated SM (S 30PP 1000); 70% FM+30% SM+1000 U phytase/kg diet (S 30P 1000); 70% FM+30% SM+2000 U phytase/kg diet (S 30P 2000); 60% FM+40% SM (S 40); 60% FM+40% 1000 U P tre SM (S 40PP 1000); 60% FM+40% SM+1000 U phytase/kg diet (S 40P 1000); and 60% FM+40% SM+2000 U phytase/kg diet (S 40P 2000). After 2 weeks of the adaptation, triplicate groups of 20 fish initially averaging 7.25±0.04 g (mean±S.D.) were randomly distributed into the aquarium and were fed one of the experimental diets for 8 weeks. By the end of the 8-week feeding trial, supplementation of phytase significantly improved the apparent digestibility coefficient (ADC) of phosphorus in rockfish diets ( P<0.05) containing 30% and 40% soybean meal regardless of the level and method of phytase supplementation. Supplementation of phytase significantly increased the ADC of dry matter in diets containing 30% soybean meal ( P<0.05). However, phytase had no influence on growth performance and whole body composition of fish. The pretreatment of soybean meal with 1000 U phytase improved weight gain (WG) when 30% fish meal protein was replaced by soybean meal. Based on the experimental results, we conclude that supplementation of phytase can improve the apparent digestibility coefficient of phosphorus in Korean rockfish.

Dietary microbial phytase supplementation and the utilization of phosphorus, trace minerals and protein by rainbow trout [Oncorhynchus mykiss (Walbaum)] fed soybean meal-based diets

Effects of thermal and enzymatic treatments of soybean meal on apparent absorption of total phosphorus, phytate phosphorus, nitrogen (protein), ash, calcium, magnesium, copper, iron, manganese, strontium and zinc were examined using rainbow trout, Oncorhynchus mykiss (Walbaum), as the test species. Absorption of the test nutrients was estimated using yttrium as an inert non-absorbable indicator. Thermal treatments (microwaving, dry roasting, steam heating, cooking) had no measurable effect on the apparent absorption of phosphorus and other minerals. Phytase supplementation increased the apparent absorption of phosphorus, nitrogen (protein), ash, calcium, magnesium, copper, iron, strontium and zinc in low-ash diets containing soybean meal, but had little effect in high-ash diets containing both soybean and fish meal. In low-ash diets, the apparent absorption of phosphorus increased in accord with the level of phytase added to the diet, from 27% (no phytase added) up to 90% (phytase added, 4000 units kg−1 diet) or 93% (predigested with phytase, 200 units kg−1 soybean meal). In high-ash diets, dietary acidification with citric acid decreased the effect of phytase, whereas in low-ash diets, acidification markedly increased the effect of the enzyme. Excretion of phosphorus in the faeces of fish fed a low-ash diet containing phytase-treated soybean meal was 0.32 g per kg diet consumed, a 95%−98% reduction compared with phosphorus excretion by fish consuming commercial trout feeds.

Effects of level of supplemental phytase on ileal digestibility of amino acids, calcium, and phosphorus in dehulled soybean meal for growing pigs.

Ileally cannulated pigs were used to assess the effects of four dietary levels of microbial phytase (Natuphos) on the apparent and true digestibility of Ca, P, CP, and AA in dehulled soybean meal. Fourteen pigs (25 kg initial BW) were surgically fitted with T-cannulas at the terminal ileum and assigned to diets in a replicated 7 x 7 Latin square design. Following a 14-d recovery, four diets consisting of 30.5% soybean meal with 0, 500, 1,000, or 1,500 units of phytase/kg of diet were fed. Diets 5 (1.05% lysine, 0.90% Ca, and 0.75% P) and 6 (1.05% lysine, 0.90% Ca, and 0.75% P) contained 35.25% soybean meal and 27.0% soy protein concentrate, respectively. Diet 7 (0.37% lysine, 0.03% Ca, and 0.05% P) was a low-CP, casein-based diet used to estimate the nonspecific endogenous losses of Ca, P, CP, and AA in order to estimate the true digestibility of these nutrients. All diets contained cornstarch and dextrose and were fortified with vitamins and minerals. Chromic oxide was used as an indigestible indicator. The diets were fed daily at 9% of metabolic BW (BW0.75). Apparent and true ileal digestibility of P increased quadratically (P < 0.01) and true digestibility of Ca increased linearly (P < 0.07) with increasing levels of phytase. Apparent digestibility of Ca was unaffected (P = 0.15) by phytase level. Apparent and true ileal digestibility of CP and most AA increased slightly with the addition of 500 units of phytase/kg of diet, but not at higher levels of phytase supplementation (in most cases, cubic effect, P < 0.05). Apparent and true ileal nutrient digestibility coefficients were unaffected by soybean meal source (Diet 1 vs Diet 5), except for arginine and Ca. The apparent and true digestibility coefficients for most of the AA tended (P < 0.10) to be lower in diets containing soy protein concentrate vs the common source of soybean meal used in Diet 5, but ileal digestibilities of Ca and P were unaffected (P = 0.15). In this study, supplemental microbial phytase did not improve the utilization of AA provided by soybean meal but was an effective means of improving Ca and P utilization by growing swine fed soybean meal-based diets.