Johan Schrama - Academia.edu (original) (raw)

Papers by Johan Schrama

Research paper thumbnail of Effect of type of dietary non‐protein energy source (starch vs. fat) on the body bile acid pool size and composition, faecal bile acid loss and bile acid synthesis in rainbow trout ( Oncorhynchus mykiss )

Research paper thumbnail of Effect of feeding level on the digestibility of alternative protein-rich ingredients for African catfish (Clarias gariepinus)

Research paper thumbnail of Variability across and within fish species in energy utilization efficiency

Dr. Johan Schrama Aquaculture and Fisheries Group, Wageningen University Mr. Thuat Phan Aquacultu... more Dr. Johan Schrama Aquaculture and Fisheries Group, Wageningen University Mr. Thuat Phan Aquaculture and Fisheries Group, Wageningen University(1) Ms. Inge Geurden INRA, UMR 1067, Nutrition, Metabolism and Aquaculture (NuMeA), Pôle d’Hydrobiologie INRA Prof. Brett Glencross Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling Dr. Sachi Kaushik INRA, UMR 1067, Nutrition, Metabolism and Aquaculture (NuMeA), Pôle d’Hydrobiologie INRA

Research paper thumbnail of Nitrogen retention, nutrient digestibility and growth efficiency of Nile tilapia ( Oreochromis niloticus ) fed dietary lysine and reared in fertilized ponds

Research paper thumbnail of Effect of exogenous enzymes (phytase and xylanase) supplementation on nutrient digestibility and growth performance of Nile tilapia (Oreochromis niloticus) fed different quality diets

Research paper thumbnail of Time‐related changes in nutrient digestibility and faecal bile acid loss of rainbow trout ( Oncorhynchus mykiss ) as affected by dietary fat level and non‐starch polysaccharide level

Research paper thumbnail of Effect of feeding during off-flavour depuration on geosmin excretion by Nile tilapia (Oreochromis niloticus)

Research paper thumbnail of The effect of dietary non-starch polysaccharide level and bile acid supplementation on fat digestibility and the bile acid balance in rainbow trout (Oncorhynchus mykiss)

Research paper thumbnail of Carbohydrate utilisation by tilapia: a meta‐analytical approach

Research paper thumbnail of Doses response of dietary viscosity on digestibility and faecal characteristics of striped catfish ( Pangasionodon hypophthalmus )

Research paper thumbnail of Characterizing emulsion properties of microalgal and cyanobacterial protein isolates

Algal Research

Abstract Photosynthetic unicellular sources contain a large variety of proteins. The types of pro... more Abstract Photosynthetic unicellular sources contain a large variety of proteins. The types of proteins vary between different microalgae and cyanobacteria. The aim was to study the effect of the variation in proteins and in non-proteinaceous components present in various unicellular protein isolates on their emulsion behavior. Algae soluble protein isolates (ASPIs, 66–77% w/w protein) of Nannochloropsis gaditana, Tetraselmis impellucida and Arthrospira (Spirulina) maxima were studied, using commercially available WPI as a reference (93% w/w protein). All protein isolates could form emulsions stable against creaming (d3,2 0.2–0.3 μm) at pH 8.0. The amount of each ASPI needed (Ccr; on protein basis) to form these stable emulsions varied between the isolates, but was within the range of proteins from both similar (photosynthetic) sources (algae and sugar beet leaves) and other protein sources (dairy, legume and egg). Minor differences were observed in the pH dependence of flocculation amongst the ASPI stabilized emulsions. For the ASPIs, the expected correlation between interfacial and molecular properties (adsorption rate constant and ζ-potential) and the emulsion behavior (Ccr and droplet size as a function of pH) was absent.

Research paper thumbnail of Differences in energy utilisation efficiencies of digestible macronutrients in common carp (Cyprinus carpio) and barramundi (Lates calcarifer)

Research paper thumbnail of Effects of feed ingredients on nutrient digestibility, nitrogen/energy balance and morphology changes in the intestine of Nile tilapia (Oreochromis niloticus )

Research paper thumbnail of Cell wall disruption: An effective strategy to improve the nutritive quality of microalgae in African catfish ( Clarias gariepinus )

Research paper thumbnail of Effect of non-starch polysaccharide composition and enzyme supplementation on growth performance and nutrient digestibility in Nile tilapia (Oreochromis niloticus )

Research paper thumbnail of Effect of ingredient particle sizes and dietary viscosity on digestion and faecal waste of striped catfish (Pangasianodon hypophthalmus )

Research paper thumbnail of The effect of phytase, xylanase and their combination on growth performance and nutrient utilization in Nile tilapia

Research paper thumbnail of Cell wall disruption increases bioavailability of Nannochloropsis gaditana nutrients for juvenile Nile tilapia (Oreochromis niloticus)

Aquaculture

Abstract In this study the correlation between the accessibility of nutrients and in vivo nutrien... more Abstract In this study the correlation between the accessibility of nutrients and in vivo nutrient digestibility was tested on the marine microalga Nannochloropsis gaditana in juvenile Nile tilapia ( Oreochromis niloticus ). It was hypothesized that disrupting the cell walls of microalgae increases the nutrient accessibility and digestibility. N. gaditana biomass was subjected to physical treatments (pasteurization, freezing, freeze drying) or mechanical treatments (bead milling) to influence its cell wall integrity. These treatments resulted in an up to 4 x increase in in vitro accessibility of N. gaditana nutrients, assessed from measurements of leaching and susceptibility to protein hydrolysis. Apparent digestibility coefficients of macronutrients, dry matter, energy, phosphorus and calcium of untreated and treated microalgae biomass were determined in triplicate, at a 30% diet inclusion level. Bead milling the algae led to the highest increase in in vivo digestibility of dry matter, energy, protein, fat, ash and calcium on ingredient level, compared to untreated algae biomass. This includes an increase in apparent digestibility coefficient (ADC) of protein and fat from 62 to 78% and from 50 to 82%, respectively. ADCs of total carbohydrates and of phosphorus were not affected by algal cell disruption. In vivo digestibilities of N. gaditana dry matter, energy, protein, and fat were positively correlated ( p r ≥ 0.91) with the nutrient accessibility of N. gaditana , as estimated with in vitro nutrient leaching analyses. This shows that the in vitro methods used are effective ways to assess the effect of mechanical and physical treatments on in vivo nutrient quality of a single ingredient. The results of this study confirm that nutrient accessibility plays a significant role in the nutrient digestibility of the microalga Nannochloropsis gaditana in Nile tilapia.

Research paper thumbnail of Hypoxia, but not an electrolyte-imbalanced diet, reduces feed intake, growth and oxygen consumption in rainbow trout (Oncorhynchus mykiss)

Scientific reports, Jan 21, 2018

Oxygen limitation and dietary imbalances are key aspects influencing feed intake (FI) and growth ... more Oxygen limitation and dietary imbalances are key aspects influencing feed intake (FI) and growth performance in cultured fish. This study investigated the combined effects of hypoxia and dietary electrolyte balance on the growth performance, body composition and nutrient utilization in a rainbow trout (Oncorhynchus mykiss) isogenic line. Fish were fed ad libitum two experimental diets: electrolyte-balanced or -imbalanced diets (DEB 200 or 700 mEq kg, respectively) and exposed to normoxia or hypoxia (7.9 or 4.5 mg O l, respectively) for 42 days. DEB did not affect FI, growth performance or body composition. Nevertheless, hypoxia had a negative impact, reducing FI (6%), growth rate (8%), oxygen consumption (19%), energy (5%) and lipid (42%) contents. Digestible energy intake and heat production were higher in normoxic fish (40% and 23%, respectively), retaining 64% more energy in lipid or protein. Hypoxia reduced the apparent digestibility of dry matter, ash, protein, lipid, carbohydr...

Research paper thumbnail of Dietary supplementation of heat-treated Gracilaria and Ulva seaweeds enhanced acute hypoxia tolerance in gilthead seabream (Sparus aurata)

Biology open, Jan 11, 2017

Intensive aquaculture practices involve rearing fish at high densities. In these conditions, fish... more Intensive aquaculture practices involve rearing fish at high densities. In these conditions, fish may be exposed to suboptimal dissolved O2 levels with an increased formation of reactive O2 species (ROS) in tissues. Seaweeds (SW) contain biologically active substances with efficient antioxidant capacities. This study evaluated the effects of dietary supplementation of heat-treated SW (5% Gracilaria vermiculophylla or 5% Ulva lactuca) on stress bioindicators in seabream subjected to a hypoxic challenge. One hundred and sixty-eight fish (104.5 g each) were distributed in 24 tanks, in which eight tanks were fed one of three experimental diets for 34 days: a control diet without SW supplementation (i), or a control diet supplemented with Ulva (ii) or with Gracilaria (iii). Thereafter, fish from 12 tanks (n= 4 tanks/dietary treatment) were subjected to 24 h hypoxia (1.3 mg O2 l(-1)) and subsequent recovery normoxia (8.6 mg O2 l(-1)). Hypoxic fish showed an increase in hematocrit values r...

Research paper thumbnail of Effect of type of dietary non‐protein energy source (starch vs. fat) on the body bile acid pool size and composition, faecal bile acid loss and bile acid synthesis in rainbow trout ( Oncorhynchus mykiss )

Research paper thumbnail of Effect of feeding level on the digestibility of alternative protein-rich ingredients for African catfish (Clarias gariepinus)

Research paper thumbnail of Variability across and within fish species in energy utilization efficiency

Dr. Johan Schrama Aquaculture and Fisheries Group, Wageningen University Mr. Thuat Phan Aquacultu... more Dr. Johan Schrama Aquaculture and Fisheries Group, Wageningen University Mr. Thuat Phan Aquaculture and Fisheries Group, Wageningen University(1) Ms. Inge Geurden INRA, UMR 1067, Nutrition, Metabolism and Aquaculture (NuMeA), Pôle d’Hydrobiologie INRA Prof. Brett Glencross Institute of Aquaculture, Faculty of Natural Sciences, University of Stirling Dr. Sachi Kaushik INRA, UMR 1067, Nutrition, Metabolism and Aquaculture (NuMeA), Pôle d’Hydrobiologie INRA

Research paper thumbnail of Nitrogen retention, nutrient digestibility and growth efficiency of Nile tilapia ( Oreochromis niloticus ) fed dietary lysine and reared in fertilized ponds

Research paper thumbnail of Effect of exogenous enzymes (phytase and xylanase) supplementation on nutrient digestibility and growth performance of Nile tilapia (Oreochromis niloticus) fed different quality diets

Research paper thumbnail of Time‐related changes in nutrient digestibility and faecal bile acid loss of rainbow trout ( Oncorhynchus mykiss ) as affected by dietary fat level and non‐starch polysaccharide level

Research paper thumbnail of Effect of feeding during off-flavour depuration on geosmin excretion by Nile tilapia (Oreochromis niloticus)

Research paper thumbnail of The effect of dietary non-starch polysaccharide level and bile acid supplementation on fat digestibility and the bile acid balance in rainbow trout (Oncorhynchus mykiss)

Research paper thumbnail of Carbohydrate utilisation by tilapia: a meta‐analytical approach

Research paper thumbnail of Doses response of dietary viscosity on digestibility and faecal characteristics of striped catfish ( Pangasionodon hypophthalmus )

Research paper thumbnail of Characterizing emulsion properties of microalgal and cyanobacterial protein isolates

Algal Research

Abstract Photosynthetic unicellular sources contain a large variety of proteins. The types of pro... more Abstract Photosynthetic unicellular sources contain a large variety of proteins. The types of proteins vary between different microalgae and cyanobacteria. The aim was to study the effect of the variation in proteins and in non-proteinaceous components present in various unicellular protein isolates on their emulsion behavior. Algae soluble protein isolates (ASPIs, 66–77% w/w protein) of Nannochloropsis gaditana, Tetraselmis impellucida and Arthrospira (Spirulina) maxima were studied, using commercially available WPI as a reference (93% w/w protein). All protein isolates could form emulsions stable against creaming (d3,2 0.2–0.3 μm) at pH 8.0. The amount of each ASPI needed (Ccr; on protein basis) to form these stable emulsions varied between the isolates, but was within the range of proteins from both similar (photosynthetic) sources (algae and sugar beet leaves) and other protein sources (dairy, legume and egg). Minor differences were observed in the pH dependence of flocculation amongst the ASPI stabilized emulsions. For the ASPIs, the expected correlation between interfacial and molecular properties (adsorption rate constant and ζ-potential) and the emulsion behavior (Ccr and droplet size as a function of pH) was absent.

Research paper thumbnail of Differences in energy utilisation efficiencies of digestible macronutrients in common carp (Cyprinus carpio) and barramundi (Lates calcarifer)

Research paper thumbnail of Effects of feed ingredients on nutrient digestibility, nitrogen/energy balance and morphology changes in the intestine of Nile tilapia (Oreochromis niloticus )

Research paper thumbnail of Cell wall disruption: An effective strategy to improve the nutritive quality of microalgae in African catfish ( Clarias gariepinus )

Research paper thumbnail of Effect of non-starch polysaccharide composition and enzyme supplementation on growth performance and nutrient digestibility in Nile tilapia (Oreochromis niloticus )

Research paper thumbnail of Effect of ingredient particle sizes and dietary viscosity on digestion and faecal waste of striped catfish (Pangasianodon hypophthalmus )

Research paper thumbnail of The effect of phytase, xylanase and their combination on growth performance and nutrient utilization in Nile tilapia

Research paper thumbnail of Cell wall disruption increases bioavailability of Nannochloropsis gaditana nutrients for juvenile Nile tilapia (Oreochromis niloticus)

Aquaculture

Abstract In this study the correlation between the accessibility of nutrients and in vivo nutrien... more Abstract In this study the correlation between the accessibility of nutrients and in vivo nutrient digestibility was tested on the marine microalga Nannochloropsis gaditana in juvenile Nile tilapia ( Oreochromis niloticus ). It was hypothesized that disrupting the cell walls of microalgae increases the nutrient accessibility and digestibility. N. gaditana biomass was subjected to physical treatments (pasteurization, freezing, freeze drying) or mechanical treatments (bead milling) to influence its cell wall integrity. These treatments resulted in an up to 4 x increase in in vitro accessibility of N. gaditana nutrients, assessed from measurements of leaching and susceptibility to protein hydrolysis. Apparent digestibility coefficients of macronutrients, dry matter, energy, phosphorus and calcium of untreated and treated microalgae biomass were determined in triplicate, at a 30% diet inclusion level. Bead milling the algae led to the highest increase in in vivo digestibility of dry matter, energy, protein, fat, ash and calcium on ingredient level, compared to untreated algae biomass. This includes an increase in apparent digestibility coefficient (ADC) of protein and fat from 62 to 78% and from 50 to 82%, respectively. ADCs of total carbohydrates and of phosphorus were not affected by algal cell disruption. In vivo digestibilities of N. gaditana dry matter, energy, protein, and fat were positively correlated ( p r ≥ 0.91) with the nutrient accessibility of N. gaditana , as estimated with in vitro nutrient leaching analyses. This shows that the in vitro methods used are effective ways to assess the effect of mechanical and physical treatments on in vivo nutrient quality of a single ingredient. The results of this study confirm that nutrient accessibility plays a significant role in the nutrient digestibility of the microalga Nannochloropsis gaditana in Nile tilapia.

Research paper thumbnail of Hypoxia, but not an electrolyte-imbalanced diet, reduces feed intake, growth and oxygen consumption in rainbow trout (Oncorhynchus mykiss)

Scientific reports, Jan 21, 2018

Oxygen limitation and dietary imbalances are key aspects influencing feed intake (FI) and growth ... more Oxygen limitation and dietary imbalances are key aspects influencing feed intake (FI) and growth performance in cultured fish. This study investigated the combined effects of hypoxia and dietary electrolyte balance on the growth performance, body composition and nutrient utilization in a rainbow trout (Oncorhynchus mykiss) isogenic line. Fish were fed ad libitum two experimental diets: electrolyte-balanced or -imbalanced diets (DEB 200 or 700 mEq kg, respectively) and exposed to normoxia or hypoxia (7.9 or 4.5 mg O l, respectively) for 42 days. DEB did not affect FI, growth performance or body composition. Nevertheless, hypoxia had a negative impact, reducing FI (6%), growth rate (8%), oxygen consumption (19%), energy (5%) and lipid (42%) contents. Digestible energy intake and heat production were higher in normoxic fish (40% and 23%, respectively), retaining 64% more energy in lipid or protein. Hypoxia reduced the apparent digestibility of dry matter, ash, protein, lipid, carbohydr...

Research paper thumbnail of Dietary supplementation of heat-treated Gracilaria and Ulva seaweeds enhanced acute hypoxia tolerance in gilthead seabream (Sparus aurata)

Biology open, Jan 11, 2017

Intensive aquaculture practices involve rearing fish at high densities. In these conditions, fish... more Intensive aquaculture practices involve rearing fish at high densities. In these conditions, fish may be exposed to suboptimal dissolved O2 levels with an increased formation of reactive O2 species (ROS) in tissues. Seaweeds (SW) contain biologically active substances with efficient antioxidant capacities. This study evaluated the effects of dietary supplementation of heat-treated SW (5% Gracilaria vermiculophylla or 5% Ulva lactuca) on stress bioindicators in seabream subjected to a hypoxic challenge. One hundred and sixty-eight fish (104.5 g each) were distributed in 24 tanks, in which eight tanks were fed one of three experimental diets for 34 days: a control diet without SW supplementation (i), or a control diet supplemented with Ulva (ii) or with Gracilaria (iii). Thereafter, fish from 12 tanks (n= 4 tanks/dietary treatment) were subjected to 24 h hypoxia (1.3 mg O2 l(-1)) and subsequent recovery normoxia (8.6 mg O2 l(-1)). Hypoxic fish showed an increase in hematocrit values r...