D. F. Houlihan

Food intake in fish.

List of Contributors. Preface. Feed Composition and Analysis (Malcolm Jobling). Feed Types, Manufacture and Ingredients (Malcolm Jobling, Emidio Gomes and Jorges Dias). Techniques for Measuring Feed Intake (Malcolm Jobling, Denis Coves, Borge Damsgard, Henrik R. Kristiansen, Juha Koskela, Thuridur E. Petursdottir, Sunil Kadri and Olafur Gudmundsson). Experimental Design in Feeding Experiments (Kari Ruohonen, Juhani Kettunen and Jonathan King). Gustation and Feeding Behaviour (Charles F. Lamb). Environmental Factors and Feed Intake: Mechanisms and Interactions (Patrick Kestemont and Etienne Baras). Environmental Factors and Feed Intake: Rearing Systems (Marie--Laure Begout Anras, Marilyn Beauchaud, Jon--Erik Juell, Deniks Coves and Jean--Paul Lagardere). Feeding Rhythms (Juan Antonio Madrid, Thierry Boujard and F. Javier Sanchez--Vazquez). Feeding Anticipatory Activity (F. Javier Sanchez--Vazquez and Juan Antonio Madrid). Effects of Feeding Time on Feed Intake and Growth (Valerie Bolliet, Mezian Azzaydi and Thierry Boujard). Effects of Nutritional Factors and Feed Characteristics on Feed Intake (Manuel de la Higuera). Regulation of Food Intake by Neuropeptides and Hormones (Nuria de Pedro and Bjorn Thrandur Bjornsson). Physiological Effects of Feeding (Chris Carter, Dominic Houlihan, Anders Kiessling, Francoise Medale and Malcolm Jobling). Feeding Management (Anders Alanara, Sunil Kadri and Mihalis Paspatis). Nutrient Partitioning and the Influence of Feed Composition on Body Composition (Malcolm Jobling). Glossary of Terms. Index

Protein growth performance, amino acid utilisation and somatotropic axis responsiveness to fish meal replacement by plant protein sources in gilthead sea bream (Sparus aurata)

Partial or total replacement of fish meal by a mixture of plant protein sources (corn gluten meal, wheat gluten, extruded peas, rapeseed meal) balanced with indispensable amino acids (IAA) was examined in juvenile gilthead sea bream (Sparus aurata) over the course of a 12-week growth trial. A diet with fish meal (FM) as the sole protein source was compared to diets with 50%, 75% and 100% of replacement (PP50, PP75, PP100). Protein retention was improved with more plant protein supply, and just a slight decrease in the final weight gain was found in fish fed PP50 and PP75 diets. However, in the PP100 group, weight gain was depressed up to 30% mainly as the result of a marked reduction of feed intake. These fish also showed a lower fat gain along with a marked hypocholesterolemic effect. Dietary treatment did not alter the hepatic activity of amino acid catabolising enzymes (alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), glutamate dehydrogenase (GDH)), although the size of the total muscle free amino acid (FAA) pool was increased by more plant protein supply. The activity of the somatotropic axis also varied among experimental groups, and the up-regulation of circulating growth hormone (GH) levels with a high plant protein supply followed the decrease in growth rates, plasma levels of insulin-like growth factor-I (IGF-I), and liver mRNA transcripts of IGF-I and GH receptors. This catabolic feature evidenced a liver desensitisation to the anabolic action of GH in the PP100 group, and to a lesser extent in the PP75 group. Taken together all these findings, up to 50-75% of fish meal replacement seems to be feasible with IAA supplementation, but further research is needed to fully identify the responsible factors for the depressed feed intake in order to achieve a full replacement in a fish species having high dietary protein requirements.

Proteomic sensitivity to dietary manipulations in rainbow trout

Changes in dietary protein sources due to substitution of fish meal by other protein sources can have metabolic consequences in farmed fish. A proteomics approach was used to study the protein profiles of livers of rainbow trout that have been fed two diets containing different proportions of plant ingredients. Both diets control (C) and soy (S) contained fish meal and plant ingredients and synthetic amino acids, but diet S had a greater proportion of soybean meal. A feeding trial was performed for 12 weeks at the end of which, growth and protein metabolism parameters were measured. Protein growth rates were not different in fish fed different diets; however, protein consumption and protein synthesis rates were higher in the fish fed the diet S. Fish fed diet S had lower efficiency of retention of synthesised protein. Ammonia excretion was increased as well as the activities of hepatic glutamate dehydrogenase and aspartate amino transferase (ASAT). No differences were found in free amino acid pools in either liver or muscle between diets. Protein extraction followed by high-resolution two-dimensional electrophoresis, coupled with gel image analysis, allowed identification and expression of hundreds of protein. Individual proteins of interest were then subjected to further analysis leading to protein identification by trypsin digest fingerprinting. During this study, approximately 800 liver proteins were analysed for expression pattern, of which 33 were found to be differentially expressed between diets C and S. Seventeen proteins were positively identified after database searching. Proteins were identified from diverse metabolic pathways, demonstrating the complex nature of gene expression responses to dietary manipulation revealed by proteomic characterisation.

Protein Turnover in Ectotherms and Its Relationships to Energetics

The regulation of the rate of synthesis of tissue proteins is of the utmost importance to the energetic cost of the maintenance and growth of the whole animal. After water, protein is the largest component of the body mass and minimal theoretical estimates of the cost of synthesising proteins indicate that they represent the most expensive molecules to produce (e.g. Kiorboe et al. 1987; Jorgensen 1988). Studies on mammals have indicated that whole body protein metabolism is closely correlated with basal energy metabolism (Garlick et al. 1976; Waterlow 1980; Meier et al. 1981), and the indications are that similar correlations exist for ectotherms (Hawkins et al. 1989). The aim of this chapter is to review the data which have recently become available on the rates of protein synthesis in ectotherms and attempt to integrate them with the likely energy cost of synthesising these proteins.

Effects of dietary amino acid profile on growth performance, key metabolic enzymes and somatotropic axis responsiveness of gilthead sea bream (Sparus aurata)

Abstract Juvenile gilthead sea bream were fed to visual satiety with isonitrogenous diets based on fish meal and different plant ingredients (33–35% replacement) supplemented with free amino acids to meet the desired indispensable amino acid (IAA) profile and dispensable amino acid (DAA) content. In diets M and WB, IAA profile and DAA content resemble that of the muscle or whole body, respectively. In diets MGlu and WBGlu, DAA content was increased by adding l -glutamic acid (Glu) and thus the IAA/DAA ratio varied from 1.13 (diet M) to 0.80 (diet WBGlu). Growth rates were not significantly different among experimental groups, but feed conversion ratio and nitrogen retention were impaired by the decrease of dietary IAA/DAA ratio. Postprandial ammonia excretion increased with the increase of dietary DAA content irrespective of IAA profile. Conversely, hepatic activity of glutamate dehydrogenase (GDH) was lower in fish fed diet WBGlu than in fish fed diet M. Hepatic growth hormone (GH) binding was not significantly affected by the dietary treatment, but circulating levels of insulin-like growth factor-I (IGF-I) and GH were, respectively, down- and up-regulated in fish fed diet WBGlu, which suggests some defect in the transmission of GH receptor signal. Fat retention and hepatic activities of lipogenic enzymes (glucose-6-phosphate dehydrogenase, G6PD; malic enzyme, ME) were decreased in fish fed diet MGlu. Key metabolic enzymes of hepatic glycolysis (glucokinase, GK) and gluconeogenesis (phosphoenolpyruvate carboxykinase, PEPCK) were also altered in this group of fish. Since soybean meal concentration was highest in diet MGlu, results on lipid and carbohydrate metabolism can be primarily attributed to this component of the diet. In contrast, data on growth performance, ammonia excretion and GH axis mainly reflect changes in the dietary amino acid profile, which reveals that a muscle IAA profile and a high IAA/DAA ratio are important in feeds for gilthead sea bream.

The effect of stress on the immune response of Atlantic salmon (Salmo salar L.) fed diets containing different amounts of vitamin C

An experiment was performed to determine the effects of dietary vitamin C levels and stress on immunological parameters in Atlantic salmon (Salmo salar L.). Atlantic salmon parr were maintained on diets containing 0.082 (low), 0.44 (normal) and 3.17 (high) g vitamin C/kg dry diet. After 23 weeks, tissue levels were found to reflect dietary input. Groups of fish were removed and subjected to a 2 h confinement stress prior to sacrifice and isolation of plasma and head kidney leucocytes. Leucocyte respiratory burst activity (P<0.01) and bactericidal activity (P<0.05) were both found to be significantly reduced by stress, but were unaffected by vitamin C status. Leucocyte migration was unaffected by stress or vitamin C status. Plasma bactericidal activity was also unaffected by vitamin C status but was significantly enhanced by stress (P<0.05). Production of specific antibody following immunisation with Aeromonas salmonicida was found to be significantly reduced (P<0.01) by stress, and there were significantly greater levels of specific antibody (P<0.01) in fish fed the low vitamin C diet compared with fish fed high levels of vitamin C.

The energetic cost of protein synthesis in isolated hepatocytes of rainbow trout (Oncorhynchus mykiss)

SummaryTo establish the energetic cost of protein synthesis, isolated trout hepatocytes were used to measure protein synthesis and respiration simultaneously at a variety of temperatures. The presence of bovine serum albumin was essential for the viability of isolated hepatocytes during isolation, but, in order to measure protein synthesis rates, oxygen consumption rates and RNA-to-protein ratios, BSA had to be washed from the cells. Isolated hepatocytes were found to be capable of protein synthesis and oxygen consumption at constant rates over a wide range of oxygen tension. Cycloheximide was used to inhibit protein synthesis. Isolated hepatocytes used on average 79.7±9.5% of their total oxygen consumption on cycloheximide-sensitive protein synthesis and 2.8±2.8% on maintaining ouabain-sensitive Na+/K+-ATPase activity. The energetic cost of protein synthesis in terms of moles of adenosine triphosphate per gram of protein synthesis decreased with increasing rates of protein synthesis at higher temperatures. It is suggested that the energetic cost consists of a fixed (independent of synthesis rate) and a variable component (dependent on synthesis rate).

The effect of short-term fasting and a single meal on protein synthesis and oxygen consumption in cod, Gadus morhua

SummaryRates of protein synthesis and oxygen consumption (

Variation in individual food consumption rates of fish and its implications for the study of fish nutrition and physiology

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