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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 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.

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

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.

International audience

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; 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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High ambient temperature impacts feed intake, growth, and nutrient utilization in pigs. However, little is known on its effects on immune function and, therefore, on how or if it could modulate the utilization of nutrients in pigs exposed to an inflammatory challenge. The aim of this study was to evaluate the effects of high ambient temperature on energy and nitrogen utilization in pigs submitted to repeated injections of Escherichia coli lipopolysaccharide (LPS). Twenty-eight catheterized and pair-housed female pigs (55 kg BW) were assigned to 1 of the 2 thermal conditions: thermoneutrality (TN, 24°C) or high ambient temperature (HT, 30°C). Within each condition, pigs had a 2-wk adaptation period in climatic-controlled rooms and then were transferred to open-circuit respiration chambers. Pigs remained in respiration chambers for a period of 18 d, which was divided into a 7-d period without LPS (baseline) and a subsequent 11-d period with LPS administration (LPSperiod). The interaction between ambient temperature and period was not significant for most of the traits studied. At baseline, pigs kept at HT had lower ADFI (1,500 vs. 2,003 g/d; P < 0.01) and ADG (449 vs. 684 g/d; P = 0.01) and similar nutrient digestibility compared with those kept at TN. Pigs kept at HT also consumed less ME (1,651 vs. 2,170 kJ·kg BW(-0.60)·d(-1); P = 0.01) and produced less heat (1,146 vs. 1,365 kJ·kg BW(-0.60)·d(-1); P < 0.01) than those kept at TN. Furthermore, HT pigs retained less protein and fat than TN pigs (-61 and -57 g/d, respectively; P < 0.01 and P = 0.01). The LPS challenge reduced (P < 0.01) nitrogen (-13.7 and -7.4 g/d) and ME intake (-594 and -335 kJ·kg BW(-0.60)·d(-1)) in TN and HT conditions, respectively; fecal digestibility of nutrients was not affected by LPS. During the LPSperiod, total heat production (HP) was decreased (P < 0.01) in both TN and HT groups (-190 and -104 kJ·kg BW(-0.60)·d(-1), respectively), in connection with the lower short-term thermic effect of feeding (P = 0.01) and resting HP (P < 0.01). In addition, the LPS induced a reduction in protein (P < 0.01) and fat deposition (P = 0.01) in pigs kept at TN (-79 and -73 g/d, respectively) and at HT (-41 and -44 g/d, respectively). In conclusion, our study confirms that high temperature reduces feed intake, growth performance, and HP. Moreover, our results evidence that irrespective of thermal condition, an inflammatory LPS challenge affects energy utilization through changes in ME intake and maintenance requirements.

Après la seconde vaccination pour l’immunocastration, les porcs immunocastrés augmentent leur niveau alimentaire, ce qui induit une augmentation des dépôts lipidiques préjudiciables à la valorisation économique des carcasses. L’objectif de l’étude a été de comparer la consommation volontaire d’aliment par des porcs immunocastrés recevant trois aliments différant par leur teneur en énergie nette (EN ; 9,10, 9,59 ou 10,07 MJ/kg) entre l’âge de 91 jours et l’abattage (à environ 172 jours). L’expérience a été conduite sur 45 porcs, logés individuellement, dont la consommation volontaire et le poids vif ont été mesurés chaque semaine. L’épaisseur de lard dorsal a été mesurée toutes les 3 semaines. A l’abattage, les carcasses ont été pesées et leur état d’engraissement a été caractérisé (épaisseur de lard dorsal, proportion de gras intermusculaire dans le cou, surface de gras adjacente au Longissimus dorsi et teneur en gras intramusculaire dans le Longissimus dorsi). Les résultats indiquent que les porcs recevant les deux régimes à faible teneur en EN ingèrent moins d’EN (33,92 vs 36,91 MJ/j avec le régime à 10,07 MJ/kg ; P = 0,05). La comparaison avec les résultats de la bibliographie indique que la capacité maximale d’ingestion d'aliment des porcs n’a pas été atteinte pendant l’expérience, suggérant que d’autres facteurs sont impliqués dans la régulation de l’ingestion chez le porc. La réduction de la teneur en EN du régime de 5% a permis de réduire l’épaisseur de lard dorsal et le poids de la bardière sans modifier le poids de la carcasse mais une réduction supplémentaire de la teneur en EN n’a pas entraîné de diminution supplémentaire de l’adiposité des carcasses., The second vaccination for immunocastration induces an increase in feed intake and fat deposition in immunocastrated pigs, which reduces carcass leanness. The objective of the study was to compare voluntary feed intake of immunocastrated pigs that received three diets differing in their net energy content (NE; 9.10, 9.59 or 10.07 MJ/kg) between 91 days of age and slaughter (around 172 days of age). The experiment involved 45 individually‐housed pigs whose voluntary feed intake and body weight were measured weekly. Backfat thickness was measured every 3 weeks. At slaughter, carcasses were weighed and their fattening status was described (backfat thickness, percentage of intermuscular fat in the neck, backfat area adjacent to Longissimus dorsi, and intramuscular fat content in Longissimus dorsi). The pigs that received the two lowest dietary NE content decreased their NE intake (33.92 vs 36.91 MJ/d with the highest dietary NE content; P = 0.05). Literature data indicate that pigs did not reach their maximal intake capacity during the experiment, which suggests that other factors may be involved in regulation of feed intake in pigs. The decrease in dietary NE content by 5% reduced backfat thickness and backfat weight with no effect on carcass weight, but a supplementary decrease in dietary NE content did not further decrease carcass adiposity.

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Chantier qualité GA; Castrated males from 2 lines of purebred French Large White obtained from a divergent selection experiment for their residual feed intake (RFI) over 7 generations were measured for their energy utilization during thermal acclimation to increased ambient temperature. The RFI+ line consumed more feed than predicted from its performance, whereas the RFI− line consumed less feed. Each pig was exposed to 24°C for 7 d (P0) and thereafter to a constant temperature of 32°C for 3 consecutive periods of 7 d (P1, P2, P3). Feed intake, feeding behavior parameters, digestibility, components of heat production (HP; measured by indirect calorimetry in respiration chambers), and energy, nitrogen, fat, and water balance were measured in pigs offered feed and water ad libitum and individually housed in respiratory chambers. Two identical respiratory chambers were simultaneously used, and 5 pigs of each line were measured successively. Whatever the trait, the interaction between line and period was not significant (P > 0.10). On average, ADFI was greater in the RFI+ than in the RFI− line (1,945 vs. 1,639 g/d; P = 0.051) in relation to an increase of the mean size of each feeding bout (128 vs. 82 g/visit; P < 0.001). There was no line effect on nutrient and energy digestibility. Total HP tended to be greater in RFI+ than in RFI− lines (1,279 vs. 1,137 kJ*kg BW-0.60*d−1; P = 0.065), which tended to retain more energy (968 vs. 798 kJ*kg BW-0.60*d−1; P = 0.050). The sensible heat loss was greater in RFI+ compared with the RFI− line (644 vs. 560 kJ*kg BW-0.60*d−1; P = 0.020). The RFI+ pigs consumed more water (+981 vs. 657 g*kg BW-0.60*d−1; P = 0.085) and produced more urine (589 vs. 292 g*kg BW-0.60*d−1; P < 0.001) than RFI− pigs, whereas water evaporation was similar for both lines. On average, ME intake and HP declined by about 38% and 20%, respectively, from P0 to P1 (P < 0.001). In contrast to ME intake, HP gradually decreased (P < 0.05) from P1 to P3 in connection with a reduction of the activity related HP. The evaporative heat loss represented 30% on the total heat loss on P0, and this proportion significantly increased on P1 (61%; P < 0.001) and remained constant thereafter. In conclusion, our results suggest that thermal heat acclimation in pigs is mainly related to a biphasic reduction of HP rather than a change in the ability of losing heat, and it did not significantly differ between RFI+ and RFI− lines despite a decreased HP in the latter ones.

Session : Alimentation; Methionine (Met) is an essential amino acid involved in several physiological functions. Methionine can be provided by dietary protein or by isomers (DL‐Met) or analogues (DL‐HMB) of L‐Met, the biologically active form of Met. Although a large number of studies have been carried out comparing the efficiencies of DL‐Met and DL‐HMB, little information is available on the efficiency of L‐Met. The objective of this study was to compare the efficiency of L‐Met (obtained by fermentation) relative to that of DL‐Met (obtained by chemical synthesis) in piglets. The study was carried out with seven treatments including a basal diet deficient in Met and three diets with three levels of additional L‐Met or DL‐Met. Feed intake, daily gain and feed efficiency increased curvilinearly with increasing levels of both sources of Met and attained a plateau at the highest levels of supplementation with no effect of the source of Met. A bent‐stick model was used to estimate the efficiency of L‐Met utilization. The model was parameterized to allow for different response trajectories between L‐Met and DL‐Met. The estimated efficiencies of L‐Met relative to that of DL‐Met were 1.15 (± 0.12), 1.12 (± 0.09), and 0.99 (± 0.12) for feed intake, daily gain and feed efficiency, respectively. None of these values differed significantly from 1, indicating L‐Met and DL‐Met can be used equally efficiently as a Met source for growth in piglets.

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Ouvrage en ligne; Dried distillers grain with solubles (DDGS) are a co-product of ethanol production from starch cereals (mainly maize in North America and wheat in Europe), which contains approximately the non-starch or non-fermentable fractions of the grain. As more becomes available with increasing bio-ethanol production, DDGS is being included not only in diets for ruminants but also in pig and poultry diets. This review paper considers the introduction possibilities of wheat DDGS in poultry and pig diets. Nutrients content in wheat DDGS and digestibility vary among ethanol plants, reflecting the starch extraction process and drying of the residues after starch extraction. Most of the variability concerns amino acid (AA) contents and their standardized ileal digestibility (SID), affected by the occurrence of Maillard reactions, reflected in the lightness score (L) of wheat DDGS. Samples with low L values (

Chantier qualité GA; Residual feed intake (RFI) has been explored as an alternative selection criterion to feed conversion ratio to capture the fraction of feed intake not explained by expected production and maintenance requirements. Selection experiments have found that low RFI in the growing pig is genetically correlated with reduced fatness and feed intake. Selection for feed conversion ratio also reduces sow appetite and fatness, which, together with increased prolificacy, has been seen as a hindrance for sow lifetime performance. The aims of our study were to derive equations for sow RFI during lactation (SRFI) and to evaluate the effect of selection for RFI during growth on sow traits during lactation. Data were obtained on 2 divergent lines selected for 7 generations for low and high RFI during growth in purebred Large Whites. The RFI was measured on candidates for selection (1,065 pigs), and sow performance data were available for 480 sows having from 1 to 3 parities (1,071 parities). Traits measured were sow daily feed intake (SDFI); sow BW and body composition before farrowing and at weaning (28.4 +/- 1.7d); number of piglets born total, born alive, and surviving at weaning; and litter weight, average piglet BW, and within-litter SD of piglet BW at birth, 21 d of age (when creep feeding was available), and weaning. Sow RFI was defined as the difference between observed SDFI and SDFI predicted for sow maintenance and production. Daily production requirements were quantified by litter size and daily litter BW gain as well as daily changes in sow body reserves. The SRFI represented 24% of the phenotypic variability of SDFI. Heritability estimates for RFI and SRFI were both 0.14. The genetic correlation between RFI and SRFI was 0.29 +/- 0.23. Genetic correlations of RFI with sow traits were low to moderate, consistent with responses to selection; selection for low RFI during growth reduced SDFI and increased number of piglets and litter growth, but also increased mobilization of body reserves. No effect on rebreeding performance was found. Metabolic changes previously observed during growth in response to selection might explain part of the better efficiency of the low-RFI sows, decreasing basal metabolism and favoring rapid allocation of resources to lactation. We propose to consider SRFI as an alternative to SDFI to select for efficient sows with reduced input demands during lactation.

In growing pigs, improving the efficiency of protein utilization by genetic selection would allow reducing the competition for protein sources between animal productions and other uses. It would also contribute to decreasing nitrogen excretion. The objective of this study was to evaluate the genetic variability of the efficiency of protein utilization in Large White (LW) pigs by quantifying the growth response to varying level of dietary protein. Sixty barrows, descendants from 9 poorly related LW boars and 17 LW x Landrace sows were offered diets supplying 85, 75 or 65% of the estimated requirements for lysine and protein. Feed allowance, equalized between pigs and slightly below the ad libitum level, and dietary protein level were adjusted each week. The test period started at 25 kg and lasted up to 15 weeks (until approximately 95 kg). Reducing the protein and lysine content resulted in a reduction in growth rate (750, 715 and 620 g/d for pigs receiving 85%, 75% and 65% of the estimated requirements respectively) and an increase in backfat thickness at slaughter (15.9, 17.4 and 19.2 mm, respectively). The sire had no effect on the efficiency of protein utilization, nor was the interaction between sire and protein content. Based on these results, the genetic variability in the efficiency of protein utilization seems insufficient to consider selection on this trait.

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International audience; Determining energy utilization in growing animals enables to adjust the nutritional constraints to nutrient requirements while maximizing the ratio between lean retention and fat retention to improve feed efficiency. In turkey production, the important sexual dimorphism and differences between strains may contribute to differences in basal energy metabolism and the partitioning of energy retention between protein and lipid. The objective of this study was to determine the dynamics of energy utilization in males and females of a heavy strain of turkeys fed ad libitum from 1 to 23 weeks of age. Heat production (HP) was determined by indirect calorimetry and retained energy (RE) was calculated as the difference between metabolizable energy (ME) intake and HP. The RE as protein was determined by a nitrogen balance, while the remaining RE was assumed to be lipid. A modeling procedure allowed partitioning HP between fasting HP (FHP), activity-related HP and thermic effect of feeding. A multiple regression analysis was used to estimate the maintenance energy expenditure (MEm) and the energy efficiencies of protein and lipid retention (kp and kf, respectively). Results were expressed either per day or per kg BW0.75 per day. In comparison with females, males consumed more feed (440 v. 368 g/day), grew faster (163 v. 147 g/day) and retained more protein (38 v. 28 g/day) during the experimental period. Expressed per kg BW0.75 per day, ME intake decreased linearly with increasing age and was not affected by gender. Similarly, RE as protein decreased with increasing age and tended to be greater in males than in females, whereas RE as lipid increased with increasing age and was lower in males than in females. In addition, HP decreased with increasing age and was greater in males than in females, because of greater activity-related HP and FHP (47% and 9% greater in males compared with females). The FHP averaged 417 kJ/(kg BW)0.75 per day during the first 3 weeks of age and decreased to 317 and 277 kJ/(kg BW)0.75 per day in males and females, respectively, from 20 weeks of age onwards. Similar to FHP, MEm was lower in females than in males ((586 to 12 × BW) and (586 to 5 × BW) kJ/(kg BW)0.75 per day, respectively) and the kp and kf were estimated at 0.63 and 0.87, respectively. This study shows that the partitioning of RE and HP differs between genders in growing turkeys, which likely results in differences in nutrient requirements.

International audience

International audience; To evaluate the digestibility of several fiber measures, three replicates of eight broilers of four-weeks age and three replicates of six broilers of five-weeks age, deriving from three Ross broilers lots, logged in metabolic cages and on four daily time-restricted 35 min feeding were used. Two diets were used, normal and fibrous, with similar nutrients to energy ratios, based on corn, wheat, soybean meal and its fibrous by-products. Block randomized design was adopted. The fibrous diet, with two times more fibre, resulted in smaller energy and protein utilization (P0,66), and this measure was considered the best to express the dietary fiber for broilers.

International audience