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Session : Nutrition et Qualité; Effet de la composition en macronutriments du régime alimentaire sur les mécanismes de croissance musculaire de la truite arc-en-ciel. 6. Journées de la Recherche Filière Piscicole

International audience; Gastrointestinal (GI) nematode control has an important role to play in increasing livestock production from a limited natural resource base and to improve animal health and welfare. In this synthetic review, we identify key research priorities for GI nematode control in farmed ruminants and pigs, to support the development of roadmaps and strategic research agendas by governments, industry and policymakers. These priorities were derived from the DISCONTOOLS gap analysis for nematodes and follow‐up discussions within the recently formed Livestock Helminth Research Alliance (LiHRA). In the face of ongoing spread of anthelmintic resistance (AR), we are increasingly faced with a failure of existing control methods against GI nematodes. Effective vaccines against GI nematodes are generally not available, and anthelmintic treatment will therefore remain a cornerstone for their effective control. At the same time, consumers and producers are increasingly concerned with environmental issues associated with chemical parasite control. To address current challenges in GI nematode control, it is crucial to deepen our insights into diverse aspects of epidemiology, AR, host immune mechanisms and the socio‐psychological aspects of nematode control. This will enhance the development, and subsequent uptake, of the new diagnostics, vaccines, pharma‐/nutraceuticals, control methods and decision support tools required to respond to the spread of AR and the shifting epidemiology of GI nematodes in response to climatic, land‐use and farm husbandry changes. More emphasis needs to be placed on the upfront evaluation of the economic value of these innovations as well as the socio‐psychological aspects to prioritize research and facilitate uptake of innovations in practice. Finally, targeted regulatory guidance is needed to create an innovation‐supportive environment for industries and to accelerate the access to market of new control tools

The objective is to systematically review the psychometric properties and the clinical utility of patient-reported outcome measures (PROMs) and proxy-reported outcome measures that assess health-related quality of life (HRQoL) among patients receiving enteral feeding to make recommendations for use in clinical practice and research. The purpose of this systematic review is to evaluate the psychometric properties and the clinical utility of:The research question is: What are the psychometric properties and the clinical utility of these measures? We will summarize evidence on the following properties: validity (content validity, criterion-related validity, construct validity, floor and ceiling effects), reliability (reproducibility and internal consistency) and responsiveness and clinical utility (interpretability and feasibility to complete the PROM and the proxy-reported outcome measure).

This study investigates muscle growth mechanisms in juvenile rainbow trout in response to isoenergetic changes in dietary non-protein energy (NPE) source (F, fat vs. C, carbohydrates) at two levels of digestible protein to digestible energy (DP/DE) ratio. Fish (initial weight 32.4 g) were fed four diets having similar DE levels (~18 kJ g−1) with a high (HP/E~26 mg kJ−1) vs. low (LP/E~14 mg kJ−1) DP/DE ratio using F or C as major NPE source (7 week-experiment). The lowering of dietary DP/DE ratio increased myoblast determination protein 1a (myod1a) and decreased myostatin 1b (mstn1b) and cathepsin D (ctsd) muscle mRNA levels. The isoenergetic change in dietary NPE from F to C decreased myod1a and proliferative cell nuclear antigen (pcna) muscle mRNA levels. An interaction between DP/DE ratio and NPE source was observed in muscle transcript levels of myogenic factor 6 (mrf4/myf6), fast myosin heavy chain (fmhc) and fast myosin light chain 2 (fmlc2). White muscle total cross-sectional area decreased at low dietary DP/DE ratio and also when NPE source changed from F to C, linked i) to a decreased total number of white muscle fibres, indicating that low dietary DP/DE restricted muscle hyperplasia and that dietary carbohydrate were less efficiently used than fat to sustain muscle hyperplasia, and ii) to decreased percentage of large muscle fibres, indicating limited fibre hypertrophy. Not only the DP level or the DP/DE ratio, but also the isoenergetic change in dietary NPE source (fat vs carbohydrates) thus appears as a potent regulator of muscle hyperplasia and hypertrophy.

In aquaculture, fish may be exposed to sub-optimal rearing conditions, which generate a stress response if full adaptation is not displayed. However, our current knowledge of several coexisting factors that may give rise to a stress response is limited, in particular when both chronic and acute stressors are involved. This study investigated changes in metabolic parameters, oxidative stress and innate immune markers in a rainbow trout (Oncorhynchus mykiss) isogenic line exposed to a combination of dietary (electrolyte-imbalanced diet, DEB 700 mEq Kg-1) and environmental (hypoxia, 4.5 mg O2 L-1) challenges and their respective controls (electrolyte-balanced diet, DEB 200 mEq Kg-1 and normoxia, 7.9 or mg O2 L-1) for 49 days. At the end of this period, fish were sampled or subjected to an acute stressor (2 min of handling/confinement) and then sampled. Feeding trout an electrolyte-imbalanced diet produced a reduction in blood pH, as well as increases in cortisol levels, hepato-somatic index (HSI) and total energy content in the liver. The ratio between the lactate dehydrogenase (LDH) and isocitrate dehydrogenase (IDH) activities decreased in the liver of trout fed the DEB 700 diet, but increased in the heart, suggesting a different modulation of metabolic capacity by the dietary challenge. Several markers of oxidative stress in the liver of trout, mainly related to the glutathione antioxidant system, were altered when fed the electrolyte-imbalanced diet. The dietary challenge was also associated with a decrease in the alternative complement pathway activity (ACH50) in plasma, suggesting an impaired innate immune status in that group. Trout subjected to the acute stressor displayed reduced blood pH values, higher plasma cortisol levels as well as increased levels of metabolic markers associated with oxidative stress in the liver. An interaction between diet and acute stressor was detected for oxidative stress markers in the liver of trout, showing that the chronic electrolyte-imbalance impairs the response of rainbow trout to handling/confinement. However, trout reared under chronic hypoxia only displayed changes in parameters related to energy use in both liver and heart. Taken together, these results suggest that trout displays an adaptative response to chronic hypoxia. Conversely, the dietary challenge profoundly affected fish homeostasis, resulting in an impaired physiological response leading to stress, which then placed constraints on a subsequent acute challenge.

Establishing the efficacy of an anti-coccidial drug in poultry begins with conducting multiple battery cage studies, where the target animals are challenged with single and mixed Eimeria species inoculum under controlled laboratory conditions. One of the primary outcomes in a battery cage study is the intestinal lesion score defined on a discrete ordinal scale of 0 to 4. So far, the statistical analysis of lesion scores has routinely employed the linear mixed model (LMM). This present work proposes to apply the generalized linear mixed model (GLMM) with the cumulative logit link to statistically analyze coccidial lesion scores collected from battery cage studies. Upon applying this new approach on 9 datasets generated by challenging battery-cage-housed broilers with various mixtures of Eimeria species, it is observed that the GLMM fitted adequately to the data, produced variance component estimates that agreed with the experimental setup, and, at the 0.05 significance level, generated statistical results in complete concordance with the LMM approach. Advantages of the proposed GLMM over the LMM are discussed from several standpoints. Parallel to the regulatory requirement of a ≥1-unit reduction in the mean lesion score for clinical relevant efficacy under the LMM, the clinical relevancy criterion under the GLMM could be set as a ≥10-fold increase in the odds of having low lesion scores. That is, the effect of an anti-coccidial drug product would be deemed clinically relevant in battery-cage studies when the odds of having low lesion scores with the medication is 10 times or more than the odds without the medication.

Résumé; Effects of dietary protein level and non-protein energy source on muscle growth mechanisms in rainbow trout (Oncorhynchus mykiss) juveniles. 18. ISFNF International Symposium on Fish Nutrition and Feeding "40 years of research in fish nutrition"

Résumé; Variability across and within fish species in energy utilization efficiency. 18. ISFNF International Symposium on Fish Nutrition and Feeding "40 years of research in fish nutrition"

Schurft veroorzaakt door Psoroptes ovis komt voor op de meeste Vlaamse bedrijven met Belgisch witblauw vleesvee. In deze studie werden twee intensieve behandelingsschema’s geëvalueerd op negen Vlaamse vleesveebedrijven met een persisterend schurftprobleem. Op bedrijf 1 tot en met 7 werden alle dieren tweemaal behandeld (met een interval van zeven à tien dagen) met een injecteerbaar macrocyclisch lacton (ML). Op de twee laatste bedrijven werd een eenmalige injectie gegeven met de ‘long acting’-formulatie (LA) van moxidectine (10%). Na behandeling werden huidafkrabsels genomen en bij de aanwezigheid van levende mijten bij ten minste één dier werden alle dieren (bedrijven 1 tot en met 7) of enkel de positieve dieren (bedrijf 8 en 9) verder behandeld met een injecteerbaar ML. Op alle bedrijven waren de dieren klinisch genezen en schijnbaar vrij van mijten na twee tot negen behandelingsrondes (twee injecties met zeven à tien dagen interval of één LA-injectie). Hoewel er op de eerste zeven bedrijven na het daaropvolgende weideseizoen opnieuw tekenen van schurft te zien waren, was dit in mindere mate en de schurft was gemakkelijker onder controle te houden.

Fasciola hepatica infection causes important economic losses in livestock and food industries around the world. In the Republic of Ireland F. hepatica infection has an 76% prevalence in cattle. Due to the increase of anti-helminthic resistance, a vaccine-based approach to control of Fasciolosis is urgently needed. A recombinant version of the cysteine protease cathepsin L1 (rmFhCL1) from F. hepatica has been a vaccine candidate for many years. We have found that vaccination of cattle with this immunodominant antigen has provided protection against infection in some experimental trials, but not in others. Differential epitope recognition between animals could be a source of variable levels of vaccine protection. Therefore, we have characterised for first time linear B-cell epitopes recognised within the FhCL1 protein using sera from F. hepatica-infected and/or vaccinated cattle from two independent trials. Results showed that all F. hepatica infected animals recognised the region 19–31 of FhCL1, which is situated in the N-terminal part of the pro-peptide. Vaccinated animals that showed fluke burden reduction elicited antibodies that bound to the regions 120–137, 145–155, 161–171 of FhCL1, which were not recognised by non-protected animals. This data, together with the high production of specific IgG2 in animals showing vaccine efficacy, suggest important targets for vaccine development. European Commission Horizon 2020

Currently, energy evaluation of fish feeds is performed on a digestible energy basis. In contrast to net energy (NE) evaluation systems, digestible energy evaluation systems do not differentiate between the different types of digested nutrients regarding their potential for growth. The aim was to develop an NE evaluation for fish by estimating the energy efficiency of digestible nutrients (protein, fat and carbohydrates) and to assess whether these efficiencies differed between Nile tilapia and rainbow trout. Two data sets were constructed. The tilapia and rainbow data set contained, respectively, eight and nine experiments in which the digestibility of protein, fat and energy and the complete energy balances for twenty-three and forty-five diets was measured. The digestible protein (dCP), digestible fat (dFat) and digestible carbohydrate intakes (dCarb) were calculated. By multiple regression analysis, retained energy (RE) was related to dCP, dFat and dCarb. In tilapia, all digestible nutrients were linearly related to RE (PPP2 for trout (NE in kJ/(kg0·8×d); dCP, dFat and dCarb in g/(kg0·8×d)). In tilapia, the energetic efficiency of dCP, dFat and dCarb was 49, 91 and 66 %, respectively, showing large similarity with pigs. Tilapia and trout had similar energy efficiencies of dCP (49 v. 57 %) and dFat (91 v. 84 %), but differed regarding dCarb.

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−1, respectively) and exposed to normoxia or hypoxia (7.9 or 4.5 mg O2 l−1, 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, carbohydrates and energy. Trout fed DEB 700 diet were energetically less efficient, reflected in higher heat production and energy requirements for maintenance. FI was inhibited by low dissolved oxygen levels, but not by electrolyte-imbalanced diet, in spite of the higher energy requirements for maintenance. This study highlights the importance that dietary-electrolyte content and DO levels have on energy balance and growth performance when fish are fed to satiation.

Rainbow trout (Oncorhynchus mykiss) was recognized as a typical ‘glucose-intolerant’ fish and poor dietary carbohydrate user. Our first objective was to test the effect of dietary carbohydrates themselves (without modification of dietary protein intake) on hepatic glucose gene expression (taking into account the paralogs). The second aim was to research if two isogenic trout lines had different responses to carbohydrate intake, showing one with a better use dietary carbohydrates. Thus, we used two isogenic lines of rainbow trout (named A32h and AB1h) fed with either a high carbohydrate diet or a low carbohydrate diet for 12 weeks. We analysed the zootechnical parameters, the plasma metabolites, the hepatic glucose metabolism at the molecular level and the hormonal-nutrient sensing pathway. Globally, dietary carbohydrate intake was associated with hyperglycaemia and down regulation of the energy sensor Ampk, but also with atypical regulation of glycolysis and gluconeogenesis in the liver. Indeed, the first steps of glycolysis and gluconeogenesis catalysed by the glucokinase and the phospenolpyruvate carboxykinase are regulated at the molecular level by dietary carbohydrates as expected (i.e. induction of the glycolytic gck and repression of the gluconeogenic pck); by contrast, and surprisingly, for two other key glycolytic enzymes (phosphofructokinase enzyme – pfkl and pyruvate kinase – pk) some of the paralogs (pfklb and pklr) are inhibited by carbohydrates whereas some of the genes coding gluconeogenic enzymes (the glucose-6-phosphatase enzyme g6pcb1b and g6pcb2a gene and the fructose1-6 biphosphatase paralog fbp1a) are induced. On the other hand, some differences for the zootechnical parameters and metabolic genes were also found between the two isogenic lines, confirming the existence of genetic polymorphisms for nutritional regulation of intermediary metabolism in rainbow trout. In conclusion, our study determines some new and unexpected molecular regulations of the glucose metabolism in rainbow trout which may partly lead to the poor utilization of dietary carbohydrates and it underlines the existence of differences in molecular regulation of glucose metabolism between two isogenic lines which provides arguments for future selection of rainbow trout., Summary: Using isogenic lines, this study determines some new, unexpected molecular regulation of the glucose metabolism in rainbow trout, which may partly lead to the poor utilization of dietary carbohydrates.

International audience; It is well known that change in environmental parameters experienced during early life can have profound effect on the metabolism of individuals later in life. The purpose of the present study was to evaluate the impact of a chronic hypoxic stimulus (15 days, 50% dissolved O2, 5.0 mg·L-1) applied at hatching (oxygen history) alone or combined with a 60% high carbohydrate (HC) dietary stimulus (8 days) applied at first-feeding (dietary history) on growth performance and glucose metabolism of juvenile trout. The effectiveness of the hypoxic and the HC dietary stimuli were verified by monitoring the modulation in mRNA levels of oxygen-sensitive and dietary carbohydrate-sensitive genes, respectively. At juvenile stage (28 weeks after first-feeding), neither dietary history nor oxygen history had long-term effect on growth performance. These juveniles were then subjected to a 5 days challenge test with a 30% carbohydrate diet. Our data showed that mRNA levels of some glucose transport-related genes in liver and muscle, and plasma triglycerides were down-regulated in fish which were exposed to hypoxia during early life. Regarding to the effect of dietary history, the mRNA level of muscular pfkmaa was observably increased in fish previously subjected to the HC dietary stimulus. In summary, the present study indicated that a chronic hypoxic stimulus applied at hatching alone or combined with a high carbohydrate stimulus at first-feeding can affect plasma triglycerides level and glucose metabolism-related genes in juvenile trout.

Cochrane Corner: Antwoord opde vraag: Wat is het effect van reminiscentietherapie (RT) op patiënten met dementie en hun mantelzorgers, aan de hand van een Cochrane Systematische Review

International audience; The aim of the study was to analyse the effects of different dietary methionine (Met) concentrations on the mechanisms of fish muscle growth (hyperplasia and hypertrophy) by using cellular and molecular approaches. Three plant-based diets differing by their Met level (MD, Met-deficient; MC, Met-control, corresponding to established Met requirement; MH, Met-high) were fed to rainbow trout juveniles for 12 weeks. Met deficiency led to a reduced somatic growth right from the first 3 weeks of feeding onwards, while feeding the MH-diet led to an increased body growth in the 6 last weeks of feeding. The protein gain of the juveniles increased with dietary Met content. The protein retention efficiency of the MD-fed juveniles was half that of the MC- and MH-fed juveniles which were statistically similar. The changes induced by MD- and MH-feeding at muscle molecular and cellular levels were different. Compared to control, dietary Met deficiency altered the expression of myogenic, muscle growth- and metabolism-related genes by increasing Myf5, MyoD1, Mrf4, Mef2a, βact, CathD, GSTπ and TNFα expressions and decreasing Col1α1 and IGF1 expressions, whereas a high level of dietary Met decreased Pax7a2, Mef2c, βact, CathD, GDH2 and NF-κB expressions. The Met-control fed fish were discrimated according to HGF, Pax7a1 and Pax7a2 expressions. Dietary Met level thus acted on the expression of genes regulating specific transition points of myogenesis, and affected the expression of muscle structural genes and growth factors involved in satellite cell activation and muscle growth. Molecular results suggested that MD-diet favours satellite cell return to quiescence, while MC-diet favours satellite cell activation and MH-diet myogenic differentiation. At cellular level, the muscle total cross-sectional area of the juveniles fed the MD-diet was 28% lower than that of the juveniles fed the MC-diet despite a similar total number of white muscle fibres, and the number of white muscle fibres with a large diameter was lower in MD-fed fish than in MC-fed ones. The muscle total cross-sectional area of the juveniles fed the MH-diet was 32% higher than that of the juveniles fed the MC-diet, their total number of white muscle fibres 25% higher, and their number of white muscle fibres with a large diameter similar. Increasing dietary methionine above established requirement thus promotes white muscle hyperplasia and muscle growth in rainbow trout juveniles, while methionine deficiency dysregulates the expression of myogenic and muscle growth-related genes and impairs white fibre hypertrophy. Statement of relevance: Determining the effects of dietary methionine levels on muscle growth mechanisms will help develop low fish meal feeds.

International audience; Two basal diets M0 and V0 were formulated with marine and plant based ingredient composition. Seven experimental diets were prepared from the two basal diets namely M0, M100, V0, V30, V60, V100 and V150 by incorporating different levels of a micromineral premix (Cu, Fe, Mn, Se and Zn). Triplicate groups of rainbow trout (initial weight: 20 g) reared at 17°C were fed one of each diet to apparent visual satiation over 12 weeks. Among the V diet fed fish, growth and feed intake exhibited maximal response at V60 level of premix inclusion; Apparent availability coefficient of Fe, Cu and Zn decreased linearly with increasing level of premix whereas apparent availability coefficient of Mn and Se was unaffected. The available dietary concentration in basal V0 diet was for Fe, 20.6; Cu, 2.8; Mn, 6.5; Zn, 17.3 and Se, 0.195 (in mg/kg DM) and in the M0 diet for Fe, 63.3; Cu, 5.2; Mn, 2.9; Zn, 35.2 and Se, 0.87 (in mg/kg DM). In reference to NRC (Nutrient requirements of fish and shrimp. Washington, DC: National Research Council, The National Academies Press, 2011) recommendations, the V0 basal diet accounted for 34.3%, 92.9%, 53.9%, 115% and 130.2% and the contribution from M0 diet for 105.5%, 173.3%, 24.2%, 234.7% and 580% of the minimal dietary inclusion levels of Fe, Cu, Mn, Zn and Se to rainbow trout, respectively. However, data on whole body mineral contents showed that normal levels were maintained only for Cu and Mn through supply from basal V0 diet. For Zn and Se, available supply even from the highest supplemented diet (V150) was not sufficient to maintain normal body mineral levels of rainbow trout in the present study. On the whole, optimal dietary inclusion levels of microminerals are altered while using fishmeal-free diets for rainbow trout.

National audience

International audience; RationaleCarbon and nitrogen stable isotope analyses of fish tissues are now commonly used in ecological studies but mostly require the sacrifice of the animal. Ethical considerations recommend the use of anesthetics for tissue sampling. This study examines how anesthetics affect stable isotope ratios of fish compared with other euthanasia methods.MethodsRainbow trout fry and juveniles were sacrificed using ice-freezing (as this common method used to kill fish does not affect natural isotopic ratios), electronarcosis or an overdose of chemical anesthetics (2-phenoxyethanol, benzocaine and clove oil). For fry, we sampled the whole animal whereas, for juveniles, white dorsal muscle, liver, red blood cells, plasma, external tegument and pectoral fin were sampled. Isotopic ratios and the elemental compositions of carbon and nitrogen were then measured.ResultsThe δ15N values, and the C and N contents of all considered tissues as well as δ13C values of muscle, liver, red blood cells and plasma, were not affected by the use of chemical anesthetics. Clove oil and to a lesser extent 2-phenoxyethanol and benzocaine decreased δ13C values of whole fry and juvenile external tegument and pectoral fin. The use of electronarcosis drastically affects the δ13C and δ15N values of all fish tissues.ConclusionsAnesthetics should be avoided for δ13C analysis when tissues are in contact with the water containing the anesthetic. Ice-immersion has to be preferred when approved by guidelines. If not, benzocaine and 2-phenoxyethanol should be preferred over clove oil. Electronarcosis should not be used to kill fish until further investigations are performed.

Detection of liver molecular markers linked to a plant-based diet utilization in different rainbo trout genotypes. Aquaculture Europe 2017

Résumé; An acute hypoxic exposure during early life affects the MRNA level of glucose metabolism-related genes at first-feeding in rainbow trout (Oncorhynchus mykiss). Aquaculture Europe 2017

International audience

Résumé; Dietary methionine restriction decreases oxidative stress in rainbow trout liver through autophagy-mediated mitochondrial degradation. Aquaculture Europe 2017

Ability to grow and survive with 100 % plant-based diet in rainbow trout : contrasted genotypes help to understand underlying mechanisms. XVI congreso nacional de acuicultura - Journée Franco Espagnole

International audience

Successful selection of rainbow trout (Oncorhynchus mykiss) on their ability to grow with a diet completely devoid of fishmeal and fish oil. 68. Annual Meeting of the European Federation of Animal Science (EAAP)

The current guideline was written to aid in the design, implementation and interpretation of studies for the assessment of drug efficacy against non-coccidial gastrointestinal protozoan parasites, with Giardia spp. as the leading example. The information provided in this guideline deals with aspects of how to conduct controlled studies using experimental infection models (dose determination and dose confirmation) and efficacy studies in commercial facilities (field effectiveness studies). Furthermore, the selection of suitable animals, housing, infection procedure, choice of diagnostic technique and data analysis are discussed. This guideline is intended to assist investigators in conducting specific studies, to provide specific information for registration authorities involved in the decision-making process, to assist in the approval and registration of new drugs and to facilitate the worldwide adoption of uniform procedures. The primary parameter for drug efficacy is the reduction in either parasite excretion or parasite counts and a minimum efficacy of 90% is required against non-coccidial gastrointestinal protozoa. A supporting efficacy parameter is a significant difference in the proportion of infected animals between treated and non-treated groups. Persistent efficacy is considered as an additional claim to therapeutic efficacy.

Malnutrition is a known problem in hospitals and nursing homes. This study aims to evaluate the prevalence of being at risk of malnutrition in community living adults receiving homecare nursing and to determine factors independently associated with this risk of malnutrition. Furthermore, it also aimed to describe aspects of current nutritional nursing care. Patients (n = 100) are screened with the Malnutrition Universal Screening Tool to evaluate their risk of malnutrition. A patient survey was used to analyse associated factors. In this population, 29% are at risk for malnutrition. Following a multivariate logistic regression analysis, loss of appetite proved the most important factor. A survey for nurses (n = 61) revealed low awareness, poor knowledge, poor communication between stakeholders and a moderate approach of malnutrition. These findings should encourage homecare nurses to use a recommended screening tool for malnutrition and to actively observe and report loss of appetite to initiate the prescription of individual tailored interventions. Belgian homecare nurses' management does not yet fully comply with international recommendations. Additional training in nutritional nursing care and screening methods for malnutrition is needed. Systematic screening should be further developed and evaluated in this at-risk population.