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Corn‐fermented protein products (CFP) from the bioethanol industry have strong potential as alternatives to traditional plant protein sources in finfish diets. This study examined the culture performance, apparent digestibility, intestinal histology, and expression of gut inflammation markers in juvenile Rainbow Trout Oncorhynchus mykissfed experimental diets with graded levels of soybean meal and CFP. Four experimental diets were formulated to contain 40% protein and 20% lipids, and the diets incrementally replaced soybean meal with CFP (0% [Control], 25%, 50%, or 100% replacement). Juvenile Rainbow Trout (48.9 ± 1.3 g) were randomly distributed to 12 100‐L tanks within a recirculating aquaculture system (30 fish/tank). Fish were fed one of the four experimental diets on a restricted feeding regime (1–3% biomass/day), and tanks were weighed every 14 days for 70 days. The mean weight, specific growth rate, feed conversion ratio, survival, and proximate composition of fish were not significantly different (α = 0.05) between the diet groups after 70 days of feeding (139.6 ± 7.5 g final weight). Apparent protein digestibility was significantly higher in the 50% CFP diet group than the Control group (80.3 ± 1.2% and 77.6 ± 1.2%, respectively). Histological analysis of distal intestines showed significantly larger villi lengths and villi length‐to‐width ratios in fish fed the 100% CFP diet, relative to fish fed the Control and 25% CFP diets. The expression of gut inflammation markers tumor necrosis factor alpha (TNF‐α), interleukin (IL)10, and matrix metalloproteinase‐9 (MMP9) trended lower in the 50% and 100% CFP diet groups compared to the Control group. The expression of the nutrient absorption markers PepT1 and FABP2 trended higher in the 50% and 100% CFP diet groups relative to the Control group. The results of this study suggested that the replacement of soybean meal with CFP in Rainbow Trout grow‐out diets did not impair growth performance and improved overall protein digestibility and gut health. Impact statementThis study evaluated the use of a value‐added corn ethanol by‐product as a protein and fat source in Rainbow Trout feeds. This new ingredient could be more affordable than traditional plant protein and fat sources in trout feeds and would not divert a potential human food crop (soybean) towards animal feeds. The study found that replacing soybean‐based protein and fat sources in trout feeds with the value‐added corn ethanol by‐product did not affect fish growth rates but did improve gut health and protein digestibility. These results support the use of this new ingredient in trout feeds and the study offers a good launch point for future research on the topic. This study evaluated the use of a value‐added corn ethanol by‐product as a protein and fat source in Rainbow Trout feeds. This new ingredient could be more affordable than traditional plant protein and fat sources in trout feeds and would not divert a potential human food crop (soybean) towards animal feeds. The study found that replacing soybean‐based protein and fat sources in trout feeds with the value‐added corn ethanol by‐product did not affect fish growth rates but did improve gut health and protein digestibility. These results support the use of this new ingredient in trout feeds and the study offers a good launch point for future research on the topic.

Live food is necessary for the proper development of zebrafish larvae, providing nutrition in a form that is easily digestible and available to the larvae. Live food is commonly enriched to increase the dietary content of certain nutrients. However, little research has been done on protein-based enrichments, especially those of plant origin. This study sought to examine how different quality protein enrichments affected the composition of live food as well as growth and digestive tract development of larval zebrafish, Danio rerio. Larval zebrafish were fed from 3 to 22 days posthatch (dph) with one of six live food (rotifers Brachionus plicatilisand Artemiaspp.) treatments: (1) live food with no enrichment (starved; control); (2) live food enriched with commercially used Spirulina spp. algae; (3) live food enriched with soybean meal (SBM); (4) live feed enriched with soy protein concentrate (SPC); (5) live feed enriched with a fishmeal hydrolysate; and (6) live feed enriched with intact fishmeal (FM). Proximate composition of live food was significantly affected by enrichment, in particular, protein content of rotifers was significantly increased by enrichment with SBM. Zebrafish fed SBM-enriched live food showed longer total body length than all other groups, except SPC. Zebrafish in the SBM group also showed increased gene expression of chymotrypsin in the intestine, possibly indicating improved intestinal development and extracellular digestion, which likely contributed to improved growth. Conversely, zebrafish fed hydrolysate-enriched live food showed reduced gene expression of alkaline phosphatase, possibly indicating a less developed intestinal tract, correlating with reduced growth compared to SBM group. Overall, plant protein was shown to be a promising source of live food enrichment for improving larval zebrafish growth.

The negative effects of dietary soybean meal (SBM) can be counteracted with the use of nutritional programming (NP). Nutritional programming is an early feeding event during larval or juvenile stages that can alter physiological responses of the fish later in their life. The objective of this study was to assess the effect of introducing diets containing SBM or soy saponin to larval Largemouth Bass Micropterus salmoideson growth performance and gut microbiome composition of the fish in their pre‐adult stage.The study found that NP introduced with a formulated SBM diet or dietary saponin for 21 d during the larval stages did not improve SBM utilization and growth performance in the pre‐adult age, which likely resulted from poor utilization of dry feeds in Largemouth Bass during first feeding. Our study also found that NP with an SBM diet or dietary saponin did not have any significant effects on the Largemouth Bass gut microbiome, and there did not seem to be any gut microbiome modification associated with NP. However, age‐related changes in the gut microbiome were documented.

Long‐recognized physiological actions of black pepper Piper nigrumand turmeric Curcuma longaplants or their active ingredients (piperine [Pip] and curcumin [Curc], respectively) have been tested in nutritional and clinical experiments. Available data suggest that both dietary additives influence food acceptance, metabolism, and digestive physiology and increase the bioavailability of several drugs and nutrients. Therefore, the main goal of this study was to test how Common Carp Cyprinus carpiorespond to diets supplemented with Pip, Curc, and black pepper extract (BP) in terms of food intake, growth, whole‐body composition, and muscle free amino acid (FAA) levels. We used the following dietary treatments: a reference diet based on casein and gelatin (CG), a diet in which a fraction of CG protein (20%) was replaced with an FAA mixture (Met0.4 [methionine 0.4%]), and three other diets identical to Met0.4 but supplemented with 0.02% Pip, Curc, or BP. We found that addition of spices and their active ingredients impacted fish growth (BP depressed growth by 30%); however, these dietary additives did not show any significant effect on food intake across the treatments. Dietary Pip increased total lipids in the whole body. The total indispensable FAA level was higher in the Curc group compared to the CG group only. The total dispensable FAA level in the BP group was higher than those in the CG and Met0.4 groups but was not different than those in the Pip and Curc groups. We conclude that further study is warranted with different levels of spices in fish diets. A summary of the current state of knowledge on the effect of Pip on nutrient flux and nutrient utilization, as well as possible regulatory mechanism(s) involved in the action of spices in fish, with a focus on Pip, is also provided.

Nutritional programming (NP) is considered a promising approach that can counteract the negative effects of dietary plant protein (PP) by introducing PP to fish in the early developmental stages. Therefore the objective of our study was to assess the effect of NP on PP utilization and the gut microbiome in zebrafish Danio rerio. The study included four treatment groups: (1) a positive control group that received a fishmeal (FM) diet throughout the entire trial (+ control); (2) a negative control group that received PP diet throughout the entire trial (− control); (3) an NP group that received dietary PP during the larval stage followed by FM-based diet during the juvenile stage and PP diet again during a PP challenge in the grow-out phase (NP-PP); and (4) an FM-group that received FM-based diet during the larval and juvenile stages and was challenged with a PP diet during the grow-out phase (NP-FM). During the PP challenge, the NP-PP group achieved the highest weight gain compared to the (−) control and NP-FM groups. The relative abundance of certain phyla such as Chloroflexi, Planctomycetes, and Bacteroidetes presented higher values in some groups at early juvenile stage. The fish gut microbiome also presented differences throughout the study.

The tolerance of eyed‐stage embryos of Walleye Sander vitreusto cooling at melting‐ice temperatures and their subsequent hatching and rearing to advanced juveniles were examined. Embryos (71% viable; 8 d after fertilization) were refrigerated in an insulated transportation Styrofoam box between wet cheesecloth layers and melting ice (1.4°C) for 25, 48, 72, and 120 h. Embryos were then acclimated to 14°C aquaria for hatching and rearing (20°C). The hatching of embryos and their ability to continue development (swim bladder inflation), food acceptance (live nauplii of brine shrimp Artemiaspp.), and growth were monitored for 14 d. The duration of exposure to cold storage stress resulted in no significant differences in mean ± SDsurvival (46.8 ± 8.0, 38.7 ± 8.6, 41.0 ± 4.9, and 36.9 ± 12.5% for 25‐, 48‐, 72‐, 120‐h treatments, respectively) at the end of the rearing and feeding period. However, the proportion of fish with inflated swim bladders was the highest in the 120‐h cold‐delayed fish (mean ± SD= 61 ± 18, 54 ± 8, 64 ± 3.8, and 90.5 ± 8%, respectively). The mean weight of fish was not significantly influenced by cold storage treatments but was significantly influenced by swim bladder status (9.2–11.8 mg, 7.0–9.8 mg, and 5.7–9.5 mg for fully inflated, partially inflated, and uninflated groups, respectively). This experiment provides significant new data to fish culturists regarding the storage of Walleye embryos prior to hatching and the possibility of convenient transportation or delayed stocking of larvae into prepared nursing ponds or indoor rearing tanks for intensive culture.

Gender identification of fish species is carried out mainly by examining external morphological characteristics, which in general, it is very complex and not always a reliable approach. Electrophoresis of plasma proteins can be used as an alternative and useful molecular tool for a more precise sex determination. The presence of female specific proteins in the plasma is a starting point for the application of this technique. In this study, reducing discontinuous sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was applied to analyze plasma proteins of male and female koi carp (Cyprinus carpio haematopterus). Image analyses of electrophoregrams with resolved plasma proteins by SDS-PAGE showed that it is an appropriate technique to discriminate male from female samples. It is based on the presence of apolipoprotein B-100 which can be used as a suitable marker. Further amino acid characterization of apolipoprotein B-100 confirmed that it is a specific protein for female individuals.

AbstractThe objectives of this study were to (1) evaluate if dietary lysine (Lys) has an effect on the free amino acid (FAA) pool of Yellow Perch Perca flavescenseggs, and (2) determine how dietary Lys influences the reproductive performance and eggs fertilization rate (embryo survival) of female Yellow Perch. Two-year-old Yellow Perch of initial size of approximately 75 g were randomly distributed into six 400-L tanks at 32±1 fish per tank. This experiment included two wheat gluten-based diets in triplicate Lys-deficient ([−]Lys) and Lys-supplemented ([+]Lys; 2.23% in dry feed) diets. Females from the reference group were fed a commercial diet. Females from reference, (+)Lys, and (−)Lys groups were stripped and their eggs divided into 0.4–1.2-g portions and mixed with sperm (21.4±4.3 μL) from either reference, (+)Lys, or (−)Lys males. The mean weight of Yellow Perch females and mean total weight of ovulated eggs were the greatest in the reference group compared with both (+)Lys and (−)Lys groups. There were no differences in the ratio of weight of eggs to female body weight as well as egg size among groups. There was no difference among treatments in the concentration of free amino acids except glutamic and aspartic acids in Yellow Perch eggs. There was significant effect of female dietary treatments on the egg fertilization rate averaged across all males. The higher fertilization rate was observed in the reference and (+)Lys groups compared with the (−)Lys group. The effect of female dietary treatment on the egg survival was also dependent on the dietary treatment of males.Received October 8, 2013; accepted March 31, 2014

The objectives of this study were to (1) evaluate if dietary lysine (Lys) has an effect on the free amino acid (FAA) pool of Yellow Perch Perca flavescenseggs, and (2) determine how dietary Lys influences the reproductive performance and eggs fertilization rate (embryo survival) of female Yellow Perch. Two-year-old Yellow Perch of initial size of approximately 75 g were randomly distributed into six 400-L tanks at 32±1 fish per tank. This experiment included two wheat gluten-based diets in triplicate Lys-deficient ([-]Lys) and Lys-supplemented ([+]Lys; 2.23% in dry feed) diets. Females from the reference group were fed a commercial diet. Females from reference, (+)Lys, and (-)Lys groups were stripped and their eggs divided into 0.4–1.2-g portions and mixed with sperm (21.4±4.3 µL) from either reference, (+)Lys, or (-)Lys males. The mean weight of Yellow Perch females and mean total weight of ovulated eggs were the greatest in the reference group compared with both (+)Lys and (-)Lys groups. There were no differences in the ratio of weight of eggs to female body weight as well as egg size among groups. There was no difference among treatments in the concentration of free amino acids except glutamic and aspartic acids in Yellow Perch eggs. There was significant effect of female dietary treatments on the egg fertilization rate averaged across all males. The higher fertilization rate was observed in the reference and (+)Lys groups compared with the (-)Lys group. The effect of female dietary treatment on the egg survival was also dependent on the dietary treatment of males.

AbstractThe objective of the present study was to determine whether lysine (Lys) supplementation influences the maturation and sperm quality of Yellow Perch Perca flavescens. Juveniles raised on a formulated commercial diet and weighing approximately 75 g each were randomly distributed into six 400-L tanks. This experiment included two wheat-gluten-based diets in triplicate: (−) Lys (Lys-deficient) and (+) Lys (Lys-supplemented; 2.23% in dry feed) diets. In addition, 16 control fish were kept under identical conditions and fed a commercial diet. The weight of males was larger in the control group than in the (+) Lys and (−) Lys groups. The sperm concentration was significantly higher in the control and (+) Lys groups than in the (−) Lys group. Sperm motility was lower in the (−) Lys group than in the control and (+) Lys groups. The control group had significantly higher protein concentration in its seminal plasma than did the (+) Lys and (−) Lys groups. The seminal plasma trypsin inhibitor activity showed the same trend. The seminal plasma free amino acid concentrations of arginine, methionine, threonine, glutamine, alanine, and glycine differed significantly among treatments. This is the first report demonstrating the negative effect of dietary lysine level in plant-protein-based diets on reproduction in fish.Received June 19, 2013; accepted October 13, 2013

The objective of the present study was to determine whether lysine (Lys) supplementation influences the maturation and sperm quality of Yellow Perch Perca flavescens. Juveniles raised on a formulated commercial diet and weighing approximately 75 g each were randomly distributed into six 400-L tanks. This experiment included two wheat-gluten-based diets in triplicate: (-) Lys (Lys-deficient) and (+) Lys (Lys-supplemented; 2.23% in dry feed) diets. In addition, 16 control fish were kept under identical conditions and fed a commercial diet. The weight of males was larger in the control group than in the (+) Lys and (-) Lys groups. The sperm concentration was significantly higher in the control and (+) Lys groups than in the (-) Lys group. Sperm motility was lower in the (-) Lys group than in the control and (+) Lys groups. The control group had significantly higher protein concentration in its seminal plasma than did the (+) Lys and (-) Lys groups. The seminal plasma trypsin inhibitor activity showed the same trend. The seminal plasma free amino acid concentrations of arginine, methionine, threonine, glutamine, alanine, and glycine differed significantly among treatments. This is the first report demonstrating the negative effect of dietary lysine level in plant-protein-based diets on reproduction in fish.