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Les travaux de recherche sur l’alimentation des porcs ont été conduits par l'INRAgrâce au soutien financier de partenaires privés via des collaborations bilatérales avec des firmes services (ou des producteurs et vendeurs d’additifs) ou des collaborations plus larges regroupant une grande partie des acteurs de l’alimentation animale. Les principaux outputs de ces travaux de recherche ont été : (1) des concepts et méthodes de référence pour caractériser la valeur des ressources et les besoins des animaux, (2) des outils d’aide à la décision (OAD) pour faciliter la diffusion et l’appropriation des connaissances auprès des acteurs de la filière au niveau national et international. Les résultats de ces travaux ont été utilisés et diffusés hors de la sphère académique grâce à des activités d’intermédiation (expertises, réunions techniques) réalisées d’abord par les chercheurs eux-mêmes. Les firmes services françaises (notamment celles associées au GERNA ) ont rapidement intégré et adapté les nouveaux concepts d’évaluation des aliments pour que leurs clients bénéficient des progrès réalisés, tant pour l’énergie (énergie digestible vers énergie nette (EN)), que pour l’azote, sur leur marge nette de production. Certaines entreprises privées (Ajinomoto Eurolysine) ont financé la diffusion des résultats (aide à la production d'outils d’aide à la décision) et ont également utilisé leur réseau commercial en France et dans le monde pour aider à leur mise en pratique. Enfin, la diffusion de la connaissance sur l’adéquation entre les besoins et les apports nutritionnels pour limiter les rejets a été en grande partie effectuée grâce aux recommandations successives du CORPEN dans lequel l’INRA a eu un rôle déterminant. Au niveau de la filière porcine française et européenne, les systèmes d’alimentation chez le porc que l’INRA a conçus ont eu des impacts sur les trois piliers de la durabilité. Au niveau économique et social, ils ont permis d’améliorer la rentabilité de différents maillons de la filière (firmes services, producteurs d’aliment, coopératives et groupements d’éleveurs, éleveurs) et de préserver les emplois directs et indirects liés à l’élevage porcin dans le contexte des années 80 où le nombre d’éleveurs était en forte baisse. Ces évolutions ont aussi permis à la France de devenir autosuffisante en viande de porc alors qu’elle était fortement importatrice au début des années 80. Sur le plan environnemental, l'alimentation des animaux a été un levier d'action important qui a permis de réduire de façon très significative les pertes d'azote et de phosphore. Les travaux conduits et l’expertise des chercheurs ont eu un rôle moteur dans les réflexions qui ont mené à l’établissement, l’acceptation et l’évolution de normes environnementales plus strictes. En prenant en compte l’évolution de la production de porc, la réduction des rejets en azote et en phosphore peut-être évaluée à 11% et 46% à l’échelle nationale entre 1984 et 2010. L'étude de ce cas a été réalisée selon la méthode ASIRPA.

Minerals are essential for the development and maintenance of the skeletal system as well as for many essentialphysiological functions. The factorial determination of minerals requirement is generally based on potential totalbody minerals retention as driving force. However, only very limited information is available in reproductive sows,data from fattening pigs being often used, which makes the predictions unprecise. Complete dissection (lean, fat,bones, skin, organs) was performed on 189 sows, among which 23 were also chemically analysed. Body minerals and protein contents were determined in all sows using the double-regression technique. Sows were from different parities and different physiological status: 42 and 66 primiparous sows at farrowing and at weaning, and 25 and 56 multiparous sows at mating and at farrowing, respectively. Body minerals weight (BM) was greater (P

The aim of this study was to evaluate the associated effects of ambient temperature and inflammation caused by repeated administration of Escherichia coli lipopolysaccharide (LPS) on insulin, energy, and AA metabolism. Twenty-eight pigs were assigned to one of the two thermal conditions: thermoneutral (24 °C) or high ambient temperature (30 °C). The experimental period lasted 17 d, which was divided into a 7-d period without LPS (days −7 to −1), and a subsequent 10-d LPS period (days 1 to 10) in which pigs were administered 5 repeated injections of LPS at 2-d intervals. Postprandial profiles of plasma insulin and nutrients were evaluated through serial blood samples taken on days −4 (P0), 4 (P1), and 8 (P2). Before the LPS-challenge (P0), postprandial concentrations of glucose, lactate, Gln, Ile, Leu, Phe, Tyr, and Val were greater in pigs kept at 24 °C than at 30 °C (P < 0.05). In contrast, Arg, Asp, Gly, His, and Met postprandial concentrations at P0 were lower at 24 °C than at 30 °C (P < 0.05). At both 24 and 30 °C conditions, pigs had greater postprandial concentrations of insulin (P < 0.01) and lower concentrations of NEFA (P < 0.01) and α-amino nitrogen (P < 0.05) at P1 and P2 than at P0. Compared with P0, postprandial concentrations of glucose were greater (P < 0.05) at P1 in pigs kept at 24 °C, and at P1 and P2 in pigs kept at 30 °C. At both ambient temperatures, pigs had lower (P < 0.05) postprandial concentrations of Ala, Gly, His, Ile, Leu, Pro, Ser, Thr, Trp, and Val at P1 and P2 than at P0. Arginine postprandial concentration at P1 was lower than at P0 in pigs kept at 24 °C (P < 0.05), whereas no difference was observed in pigs at 30 °C. Relative to P0, Gln and Tyr concentrations were lower at P1 and P2 in pigs kept at 24 °C (P < 0.01), whereas lower Gln concentration was observed only at P2 (P < 0.01) and lower Tyr only at P1 (P < 0.01) in pigs kept at 30 °C. Our study shows a hyperglycemic and hyperinsulinemic state in LPS-challenged pigs and a greater magnitude of this response in pigs kept at 30 °C. Furthermore, LPS caused important changes in BCAA, His, Thr, and Trp profiles, suggesting the role these AA in supporting the inflammatory response. Finally, our results suggest that LPS-induced effects on postprandial profiles of specific AA (Arg, Gln, Phe, and Tyr) may be modulated by ambient temperature.

International audience; The cost of feed contributes largely to the cost of pig production and energy represents the largest part of this cost. An appropriate assessment of the energy value of feed ingredients and diets is therefore very important in feed formulation. Likewise, it is important to understand and to quantify how an animal uses its dietary energy, which is often referred to as the energy requirement. To be meaningful, energy values and energy requirements must “talk the same language”. For example, in a net energy (NE) system, the marginal efficiencies with which nutrients are used are attributed to the NE value of the ingredients or the diet. Consequently, these efficiencies are no longer accounted for in the NE requirement. In an ME system, only the material energy losses are accounted for in the ME value of an ingredient and the efficiency with which the energy is used is accounted for in the energy requirement as the cost of energy retention. The choice of an energy system has an important impact on the relative energy values of different feed ingredients and thus on feed formulation. Compared to starch, feed ingredients rich in fat have a higher NE value (compared to an ME value), while protein and fiber-rich ingredients have a lower NE value. Animal performance is better related to the NE intake than to the ME or DE intake and the NE system is therefore the preferred system for feed formulation in many countries. Although a NE system accounts for differences in energy efficiency among nutrients, a large part of the variation in NE values among feed ingredients originates from variation in energy digestibility. Also, the energy digestibility of a given ingredient typically increases with increasing body weight of the animal. This means that the DE value of a feed ingredient is not a property of the diet, but results from the interaction between the animal and its diet. Interactions between the diet and the animal also occur at the metabolic level. The fact that nutrients can be used for difference purposes (e.g., energy retained as protein or lipid, ATP production) has led to proposals to further refine the NE system. It is our belief that a further refinement of an NE systems is useful only if it is also accounts for interactions between the animal and its nutrients, thereby abandoning the very concept of additivity on which feed formulation is based.

International audience

The branched-chain amino acids leucine, isoleucine and valine are indispensable amino acids because they cannot be synthesized by the pig and therefore must be obtained from the diet to maintain growth and health. In hot conditions, pigs decrease nutrients intake to reduce heat production associated with digestive and metabolic processes. Therefore, ambient temperature is supposed to induce changes on amino acids partitioning and utilization. In this regard, the objective of this study was to evaluate the effects of ambient temperature on leucine, isoleucine and valine postprandial metabolism. Twenty-eight growing pigs equipped with a jugular catheter were divided into two groups and housed in thermo-neutral (TN, 24ºC) or high (HT, 30ºC) ambient temperature-controlled rooms. Pigs remained in the temperature-controlled rooms for a period of 21 days divided in a 14 days adaptation period and a subsequent seven days experimental period (from day 1 to 7). On day 4, all the animals received 300 g of feed after a fasting period overnight, and serial blood samples (4 mL) of each animal were collected over a period of four hours in order to measure plasma amino acids concentrations. Amino acids postprandial concentrations were analyzed using the linear MIXED procedure of SAS including the fixed effects of ambient temperature. The analysis of postprandial amino acids variations suggests negligible direct effects of high ambient temperature on leucine, isoleucine and valine. This absence of significant effects might be explained by the prior acclimation of pigs to the high ambient temperature. Accordingly, previous studies have demonstrated that adaptation of pigs to an ambient temperature of 30°C required three to four days.

Pigs reared in commercial conditions are often exposed to sanitary challenges. Consequently, the immune system interacts with regulatory and metabolic mechanisms to maintain animal homeostasis and integrity. For instance, a redistribution of nutrients from growth to the immune responses have been widely reported in challenged animals including pigs. However, little is known on the effects of imune system activation on amino acids metabolism in growing pigs. The aim of this study was then to evaluate the effects of an inflammatory challenge caused by repeated injections of Escherichia coli lipopolysaccharide (LPS) on the branched-chain amino acids leucine, isoleucine and valine. Fourteen growing pigs fitted with a jugular catheter were housed in a temperature-controlled room in which ambient temperature was maintained constant at 24°C. The experimental period lasted 17 days that was subdivided in a seven days period before and a 10 days period during the inflammatory challenge that consisted in five repeated injections of LPS at two days intervals. The initial dose of 30 μg/kg of body weight was increased by 12% at each subsequent injection. Before the LPS-challenge (baseline), and 24h after the second (T1) and the fourth (T2) LPS injections, 300 g of feed was given to pigs previously fasted overnight and serial blood samples were taken over four-hours to measure plasma amino acids concentrations. Amino acids postprandial concentrations were analyzed using the linear MIXED procedure of SAS including the fixed effects of time points (baseline, T1 or T2). According to our results, pigs had lower (P < 0.05) postprandial concentrations of leucine, isoleucine and valine during than before the LPS challenge. The lower plasma concentrations of the branched-chain amino acids might be associated to their increased transamination and oxidation to be used as energy source during the inflammatory challenge to support the synthesis of immune system compounds and others immune actions such as the fever response. These results suggest that the requirements for branched-chain amino acids is increased in response to inflammatory stimuli and that the supplementation of these amino acids might be advantageous in pigs exposed to immune and/or sanitary challenges.

Sanitary challenges and/or immune system activation are associated with decreased voluntary feed intake, increased metabolic rate and energy expenditure, and alterations on nutrient utilization in growing pigs. As a consequence, animals weight gain and feed efficiency are negatively impacted in such conditions. The aim of this study was then to evaluate the effects of an inflammatory challenge caused by repeated injections of Escherichia coli lipopolysaccharide (LPS) on lysine, threonine and tryptophan postprandial metabolism. Fourteen growing pigs fitted with a jugular catheter were housed in a temperature-controlled room in which ambient temperature was maintained constant at 24°C. The experimental period lasted 17 days that was subdivided in a seven days period before and a 10 days period during the inflammatory challenge that consisted in five repeated injections of LPS at two days intervals. The initial dose of 30 μg/kg of body weight was increased by 12% at each subsequent injection to circumvent adaptive endotoxin resistance to the repeated inflammatory stimuli. Before the LPS- challenge (baseline), and 24h after the second (T1) and the fourth (T2) LPS injections, 300 g of feed was given to pigs previously fasted overnight and serial blood samples were taken over four-hours to measure plasma amino acids concentrations. Amino acids postprandial concentrations were analyzed using the linear MIXED procedure of SAS including the fixed effects of time points (baseline, T1 or T2). Relative to baseline, postprandial concentrations of lysine were lower at T1 and greater at T2. In addition, the LPS-challenge induced a long-lasting (at T1 and T2) reduction in plasma postprandial concentrations of threonine and tryptophan. Firstly, these results suggest a short-term increased utilization of lysine to be used as energy source during the LPS-challenge. Then, lysine demand decreases in association with a lower protein synthesis for growth. Secondly, they evidence an increased threonine and tryptophan metabolic demand to support the requirements of the immune response. For instance, the immune system activation induces the synthesis of acute phase proteins that, in turn, have greater amounts of threonine and tryptophan in their compositions. Finally, our evidences that an inflammatory challenge caused by LPS leads to significant changes on amino acids metabolism and partitioning. induces significant changes in the postprandial metabolism of growing pigs. These findings may contribute to redefine pigs nutritional requirements during inflammatory and/or immune challenges.

High ambient temperature is one of the major environmental factors limiting animal production in tropical and subtropical areas. Pig production is particularly affected because of the high sensitivity of pigs to high ambient temperatures due to their limited capacity to dissipate heat and the high metabolic heat production of modern genotypes. The consequences of high temperature on pigs include the well described reduction in voluntary feed intake and growth but also changes on hormones and nutrients metabolism. In this regard, the objective of this study was to evaluate the effects of ambient temperature on lysine, threonine and tryptophan postprandial metabolism. Twenty-eight growing pigs equipped with a jugular catheter were divided into two groups and housed in thermo-neutral (TN, 24ºC) or high (HT, 30ºC) ambient temperature-controlled rooms. Pigs remained in the temperature-controlled rooms for a period of 21 days divided in a 14 days adaptation period and a subsequent seven days experimental period (from day 1 to 7). On day 4, all the animals received 300 g of feed after a fasting period overnight, and serial blood samples (4 mL) of each animal were collected over a period of four hours in order to measure plasma amino acids concentrations. Amino acids postprandial concentrations were analyzed using the linear MIXED procedure of SAS including the fixed effects of ambient temperature. A similar response profile was observed for the three evaluated amino acids (lysine, tryptophan and threonine) in which plasma concentrations increased immediately after the meal intake, reached peak values between 40 and 70 minutes, and decreased thereafter. According to our results, ambient temperature did not affect the postprandial profiles of the amino acids (P > 0.05) suggesting that pigs kept at 30°C had rather close metabolic statuses to those kept at 24°C in terms of lysine, tryptophan and threonine utilization.

National audience; Improving feed efficiency remains a challenge for pork production. The usual measure in herds is feed conversion ratio that quantifies the economic efficiency of feed use for animal growth. Residual Feed Intake (RFI) has been proposed as an alternative measure, independent of production traits, in the 1960's. This paper reviews the research in two divergent lines selected for RFI at INRA, the low RFI line with pigs eating less than predicted from the production and maintenance requirements, i.e. more efficient, and the high RFI line eating more than predicted for its less efficient requirements,. These studies show that selection for RFI in growing pigs is possible with a limited impact on production and sow reproduction. However, technological meat quality is unfavourably affected by selection and a control of the impacts of selection for feed efficiency on this trait is necessary, as well as for nutritional requirements of most efficient pigs. Finally, the pig's ability to respond to stressors or various breeding conditions was not affected by selection, unlike that hypothesized by the resources allocation theory applied to livestock species. The challenges for pig production to continue improving feed efficiency in a changing context for livestock production are discussed.; L’amélioration de l’efficacité alimentaire est un enjeu majeur pour la compétitivité de la filière porcine. Elle est classiquement mesurée en élevage par l’indice de consommation, indicateur économique de l’efficacité d’utilisation des aliments pour la croissance. Un critère alternatif indépendant des performances des animaux, la Consommation Moyenne Journalière Résiduelle (CMJR), a été proposé dans les années 1960. Cet article synthétise les résultats obtenus à partir de la sélection divergente de deux lignées à l’INRA, une lignée à CMJR faible, animaux consommant moins que prédit pour leurs besoins de production et d’entretien, et donc plus efficaces, et une lignée à CMJR élevée, animaux consommant plus que prédit pour leurs besoins, moins efficaces. Ces recherches montrent qu’il est possible de sélectionner pour la CMJR chez le porc en croissance avec un impact limité sur les caractères de production et de reproduction femelle, permettant ainsi de diminuer les quantités d’aliments utilisées en élevage. La dégradation des paramètres de qualité technologique de la viande en réponse à l’amélioration génétique de l’efficacité alimentaire est un point de vigilance dans les stratégies de sélection, de même que la composition nutritionnelle de la ration alimentaire. Finalement, la capacité de réponse à des stress ou à des changements de conditions d’élevage ne semble pas affectée par la sélection, contrairement à ce qui est suggéré dans la littérature en réponse à la sélection pour une CMJR réduite. Les défis qui résultent de ces résultats pour poursuivre l’amélioration de ce caractère en production tout en répondant à l’évolution des contraintes de l’élevage sont discutés.

International audience

International audience; Global warming will be one of the most important challenges facing livestock production over the next decades. In such a scenario, pig production will be affected because of the high sensitivity of pigs to high ambient temperatures as a consequence of both their limited capacity to dissipate heat and the high metabolic heat production of modern lean genotypes. In addition, pig production will be presumably more challenged by the effects of high ambient temperatures due to its important development in developing countries mainly located in tropical and subtropical areas. However, high temperature is not the unique factor impairing the sustainability and profitability of pig production. In commercial conditions, pigs have been more and more exposed to health challenges due to intensification of animal production and higher stocking density. Furthermore, the association of high relative humidity and high ambient temperature, that usually occurs in tropical and subtropical areas, benefits the proliferation and dissemination of vectors and/or pathogens (viruses, bacteria, parasites and fungi) resulting in a higher environmental pathogenic pressure. As a consequence, the immune system is activated which induces a cascade of physiological and metabolic responses that, in turn, have usually a negative impact on growth and feed efficiency. Although the specific effects of high ambient temperature and disease on animal physiology and performance have been well documented in literature, little is known about the associated effects of both factors. This understanding may contribute to a better quantification and comprehension of the physiological and metabolic disturbances occurring in practical conditions of pig production in tropical areas and, more generally, in many other geographic areas that will be impacted by the perspective of global warming. Some recent studies suggest that growing pigs previously acclimated to high ambient temperature had an improved capacity to limit the physiological and metabolic disturbances caused by an inflammatory challenge induced by repeated administrations of Escherichia coli lipopolysaccharide. Therefore, the objective of this work is to provide an overview of recent research advances (1) on the physiological responses of growing pigs during acclimation to high ambient temperature; and (2) on the potential effects of high ambient temperature on the ability of growing pigs to resist, cope or recover to health challenges.

International audience

National audience; Les porcs sont et seront soumis de plus en plus fréquemment à des températures élevées du fait du développement de l’élevage en milieu tropical et des conséquences attendues du réchauffement climatique. Dans ces conditions, ils sont aussi fréquemment exposés à des pressions sanitaires de natures très diverses. La réponse inflammatoire associée à un problème sanitaire induit une réponse physiologique très coûteuse pour l’animal, notamment du point de vue métabolique. Les effets conjoints de températures élevées et d’une activation de la réponse inflammatoire sur la physiologie des porcs ne sont pas connus. Dans ce contexte, le travail réalisé avait pour objectif 1) d’évaluer l’impact des températures chaudes sur les réponses physiologiques et la croissance du porc, et 2) d’apporter des connaissances nouvelles sur les effets des températures chaudes sur la capacité des porcs en croissance à faire face à un challenge inflammatoire. L’exposition des porcs à des températures chaudes (30°C vs 24°C) induit une réponse en deux temps. Dans un premier temps, la température interne augmente, ainsi que les pertes de chaleur, alors que la production de chaleur diminue, par l’intermédiaire de la réduction de l’ingestion d’aliment. Dans un second temps (après 24 à 48 h d’exposition), la mise en place progressive des réponses d’acclimatation se traduit par une réduction de la température interne via une réduction de la production de chaleur, indépendamment cette fois de la consommation d’aliment mais expliquées par des variations de teneur en hormones, notamment par de plus faibles concentrations sanguines en hormones thyroïdiennes et en cortisol. De manière inattendue, nos résultats montrent que l’acclimatation des porcs aux températures chaudes pourrait avoir des effets bénéfiques sur les capacités des porcs à limiter les désordres physiologiques et métaboliques causés par le challenge inflammatoire suite à des injections répétées d’endotoxines bactériennes (LPS). Ainsi, les porcs préalablement acclimatés à la chaleur ont des concentrations sériques moindres en cytokines pro inflammatoires et en protéines inflammatoires. En parallèle, l’état apparent de moindre sensibilité à l’insuline (insulinémie et glycémie augmentées après un repas) induite par le LPS perdure plus longtemps chez les porcs adaptés à la chaleur sans que cela n’affecte les concentrations circulantes en acides aminés. La croissance de ces animaux ainsi que les quantités de protéines et de lipides déposées au cours de la croissance sont également moins affectées par le challenge inflammatoire, même si elles sont plus faibles qu’à la thermoneutralité. C’est à notre connaissance la première fois que ce type de réponses croisées est rapporté chez le porc.

L'alimentation du porc représente une part majeure du coût de production (environ 60-70%) et est un puissant levier pour maitriser le niveau des performances. L'aliment et ses caractéristiques se retrouvent également dans les piliers sociétal, environnemental et économique du développement durable au travers, par exemple, de la modulation de l'impact sur l'environnement, sur le comportement et la santé des animaux ou sur la qualité des produits et, bien entendu, sur l'efficience technico-économique du système de production. L'objet de cette synthèse est de faire un état des lieux des connaissances actuelles sur la nutrition du porc et de tirer quelques perspectives sur les recherches futures. Les travaux conduits depuis 25 ans ont permis de produire, d'une part, des concepts et des données nouvelles pour évaluer les aliments tels que les acides aminés digestibles au niveau iléal, la valeur énergétique nette fonction du stade physiologique du porc ou la teneur en phosphore digestible et, d'autre part, les connaissances et les outils pour évaluer les besoins nutritionnels du porc par les méthodes factorielles ou les techniques de modélisation de façon à s'adapter à l'évolution continue des caractéristiques des animaux ou à de nouveaux objectifs, contextes et contraintes de production. Les futurs travaux et outils à développer devront viser la caractérisation rapide et fiable des aliments (méthodes NIR, par exemple), une meilleure utilisation digestive des parois végétales (par les enzymes, par exemple), une nutrition de plus en plus précise adaptée à chaque porc (modèles stochastiques) et, de façon résumée, une amélioration du rendement d'utilisation de toutes les ressources alimentaires disponibles pour leur transformation en protéines animales par le porc., Feed represents up to 60-70% of the total cost of pig production and is a powerful tool for controlling performance. Feed and its characteristics are also involved in the society, environmental and economic pillars of sustainable development including, for instance, control of the impact of animal production on the environment, animal welfare, product quality and the technical and economic efficiency of production systems. The objective of this review is to summarize the available knowledge on pig nutrition and to provide a few areas for future research. Studies conducted over the last 25 years have produced new concepts and data for evaluating feeds, such as the standardized ileal digestible amino acid content, the net energy values dependent on physiological stage or the digestible phosphorus content. They have also produced knowledge and tools for evaluating nutritional requirements according to factorial methods and modelling techniques, in order to follow regular changes in animal characteristics or in the objectives, constraints and contexts of production. Future research and new tools should focus on the rapid characterisation of the nutritional value of feeds (NIR methods, for instance), on improving the digestive utilization of dietary fibre (with enzymes, for instance), with precise nutrition adapted to each pig (stochastic models) and, more globally, on improving the efficient use of all feed resources for the pig to transform them into animal proteins.

Parallèlement à l’accroissement rapide de la production d’éthanol à partir des céréales, la disponibilité des coproduits associés, les drêches, pour l’alimentation des animaux, ruminants mais aussi porcs et volailles, s’est accrue. L’objet de cette synthèse est de considérer l’information disponible pour l’introduction des drêches de bioéthanol de céréales dans les aliments des volailles. Elle dresse le profil moyen de la composition chimique et des valeurs énergétiques et protéiques des drêches de blé et de maïs. Elle indique aussi une forte variabilité de ces critères, en particulier pour la lysine en lien avec les réactions de Maillard lors du séchage et la diminution de la luminance (L). Les échantillons de faible valeur L (< 50 pour les drêches de blé et < 30 pour les drêches de maïs) ont ainsi une teneur en lysine des matières azotées faible et cette lysine est peu digestible. La digestibilité de l’énergie des drêches de blé ou de maïs ou leurs teneurs en EM peuvent également varier avec la couleur mais elles sont surtout dépendantes de leur composition chimique et notamment de leur teneur en matières grasses et en parois végétales. Notre synthèse indique que les drêches de blé ou de maïs sont des sources potentielles d’énergie et de protéines susceptibles d’être utilisées dans les aliments des différentes catégories de volailles sans que les performances soient altérées mais à la condition que les caractéristiques nutritives des drêches soient prises en compte pour la formulation des aliments., The development of bioethanol production from cereals has also increased the use of associated by-products called distillers dried grains with solubles (DDGS) for ruminants and also for non ruminant animals. The purpose of this review was to summarize the data available in order to consider their introduction into poultry diets. Average nutrient composition and energy and amino acid values of wheat and maize DDGS are proposed. The results suggest an important variability for these parameters, especially for lysine content and lysine digestibility in relation to Maillard reactions during the drying process that cause a decrease in the luminance (L). Consequently, samples with a low L value (< 50 and < 30 for wheat and maize DDGS, respectively) have a low lysine content in their crude protein (N x 6.25) and this lysine is poorly digestible. Energy digestibility or ME content variability of wheat and maize DDGS are also correlated with colour but most of the variability is related with crude fat and dietary fibre variations. Nevertheless, our review suggests that wheat or maize DDGS can be considered as potential sources of energy and protein for poultry feeds at different stages and for different categories without any detrimental effect on performance as long as the nutritional characteristics of DOGS are taken into account in the formulation of diets.

International audience

International audience; The evaluation of the energy content of pig or poultry feeds has been most commonly based on their DE or ME contents. However, the closest estimate of the "true" energy value of a feed should be its NE content, which takes into account differences in metabolic utilization of ME of nutrients. This review considers some methodological aspects of NE determination. Experimental data in pigs indicate that the NE/ME ratio varies greatly with the chemical composition of diets and nutrient, with ratios for fat (90%) and starch (80%) that are higher than for protein and die-tary fibre (60%). This has marked consequences on the relative energy values of ingredients according to the en-ergy system that is used. The NE system is also better in predicting the performance of pigs. With regard to poultry, the ranking between nutrients for NE/ME is similar to what is observed in pigs but with smaller differences between nutrients. However, complementary data are required to propose a convincing and functional NE system for poultry. In any case, the accuracy of the NE value is highly dependent on the accuracy of DE or ME values or digestible nutrient contents that are used as predictors of NE values. Overall, there is an obvious advantage in using NE sys-tems for pigs while further investigations are required for implementing a reliable NE system for poultry.

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Foreword of Indirect calorimetry