Réduire les rejets azotés des porcs en croissance par un ajustement dynamique des apports en acides aminés au besoin et une diminution de la teneur en matières azotées totales de l'aliment

A test was performed with 96 growing pigs to implement precision feeding (PF) of restricted-fed growing pigs to characterise growth performance and N output using a PF system developed in the Feed-a-Gene project (H2020, no. 633531) compared to a 2-phase strategy (2P). A decision support tool was used to manage data (mainly individual and daily body weight (BW) measured with an automatic scale), to forecast performance on the following day, to assess corresponding amino acid requirements, and to adapt the quality of the diet delivered on the next day through the proportion of two diets used in a blend. Both diets were formulated to 9.75 MJ net energy (NE)/kg, with contrasting concentrations of digestible lysine and crude protein (A: 1.0 g lysine/MJ NE and 16.6% N x 6.25, B: 0.5 g/MJ NE and 10.9% N x 6.25). Forecasting BW and BW gain for PF pigs was interrupted for 2 weeks due to a problem with an electronic device for 2 consecutive days; it identified a problem of robustness in how forecasting methods were applied. A solution was found and applied to improve the entire system. However, no significant differences were observed between strategies for growth rate (2P: 722 vs PF: 716 g/d, P = 0.62), feed conversion ratio (2.64 vs 2.70, P = 0.063) or carcass leanness (62.0 vs 61.4 units, P = 0.18). The crude protein content of the blend provided to 2P during the growing and finishing phases was 15.8% and 13.4%, respectively. With this new 2P diet management, N output can potentially be reduced by 10% compared to a 2P with standard diets (16.0% and 15.0% N x 6.25). Despite the technical problem, which might have minimised the difference in N intake betweenstrategies, the PF contributed an additional decrease of 6%

Relations entre les impacts environnementaux, l'excrétion et les performances, chez le porc à l'engrais

The selection of animals for improved production traits has long been the major driver of pig breeding. More recently, new selection criteria are being explored, such as nitrogen (N) excretion. However, life cycle assessment (LCA) provides much better indicators of environmental impacts. The objective of this study was to investigate, using a modelling approach, relationships between production traits and LCA impacts of individual growing pigs. Impacts were calculated at the farm gate using the functional unit of one kg of body weight gain. Performances of pigs were simulated for two feeding programs − 2-phase and precision feeding − using the InraPorc population model (1,000 pigs per scenario). LCA calculations were performed for each pig according to its own performance and excretion. Results indicated that N excretion was positively correlated with feed conversion ratio (FCR; r=0.956), climate change (CC; r=0.955), acidification potential (AP; r=0.968), and eutrophication potential (EP; r=0.967), regardless of the feeding program. However, FCR appeared the best indicator of LCA impacts (better than N or P excretion), with a high positive correlation (r>0.99) with CC, AC, and EU for both feeding programs. Despite the lower CC, AP, and EP in the precision-feeding program (3%, 16% and 11% lower, respectively, than those for the 2-phase program), the correlations between performance and impacts were similar, although the ranking of pigs differed slightly. Thus, using of FCR as a selection criterion in pig breeding appears a promising approach to associate higher performance with lower environmental impact

Modelling Nutritional Requirements of Growing Pigs from Local Breeds Using InraPorc

Models such as InraPorc enable the growth of pigs to be simulated and their nutrient requirements to be determined. However, so far, these models have not been applied to local breeds. We used InraPorc to determine the nutrient requirements of growing pigs from local breeds (H2020 European Union project TREASURE). Data on feed composition, allowance and intake, and body weight (BW) were obtained from literature reports or experiments conducted within the project. Data were used in InraPorc to calibrate 16 growth and intake profiles from nine breeds (Alentejana, Basque, Bísara, Apulo Calabrese, Cinta Senese, Iberian, Krškopolje pig, Mangalitsa, and Moravka), with one to three profiles per breed depending on the experimental conditions or data source. On the 40–100 kg BW range, mean protein deposition (PDm) was low for all breeds (below 116 g/d vs. over 130 g/d in conventional breeds). The age of pigs at 40 kg BW (110 to 206 days) denoted different types of feeding management in addition to genetic differences. The PDm and the lysine requirements were the highest in breeds with the highest average daily gain. In all breeds, a small proportion of total body energy retention was dedicated to protein, with the greatest proportion of energy retention in the form of lipids. Despite some methodological limitations, this study provides initial insights into the nutrient requirements of some local breeds

Taking advantage of responsible digital for sustainable livestock farming systems

International audienc

Étude des interactions dipolaires induites par la lumière dans des ensembles d'atomes froids

Our team studies the collective behaviour of an atomic gas in the presence of dipole-dipole interactions. These interactions appear when the atoms are illuminated by a laser of wavelength lambda that is nearly resonant with an atomic transition : the atoms are polarized by the laser field, and the induced dipoles interact with each other through the field they radiate. This interaction becomes stronger when the atoms are closer to each other, and can considerably perturb the radiative behaviour of the atomic ensemble, or even prevent the simultaneous excitation of several atoms. For instance, a dense atomic cloud can behave like an optical cavity without any mirrors : the laser can excite certain radiation modes, each with its own frequency and life time, which are different from those of an individual atom. Some of these collective modes are super-radiant (the atomic cloud re-emits the stored excitation faster than an individual atom), others are sub-radiant.In order to study these phenomena, our team has built an experiment that allows the trapping of 1 up to ~500 cold rubidium atoms in a laser trap of ~1µm³ in size. We excite the atoms close to the transition at 780nm. The size of the atomic cloud, on the order of 100 nm, is close to the reduced wavelength. Also, the Doppler broadening of the atomic transition is negligible (cold atoms). The situation is therefore nearly ideal for the observation of the collective radiation modes. We observed the effects of these interactions, but no quantitative agreement with theory has been obtained so far (despite our efforts to simplify the internal atomic structure).We have thus decided to build a second version of the experimental apparatus. This challenging second version now possesses two high resolution optical axes. Not only solving some experimental problems of the previous version, it opens the road to new kind of experiments to study dipolar interactions: new regime of densities and new kind of geometries, as 1D chain of atoms for instance.Notre équipe étudie le comportement collectif d’un gaz d’atomes en présence d’interactions de type dipôle-dipôle. Ces interactions apparaissent lorsqu'on illumine les atomes avec un laser de longueur d’onde quasi-résonant avec une transition atomique : les atomes se polarisent sous l’effet du champ laser, et les dipôles induits interagissent entre eux via le champ qu’ils rayonnent. Cette interaction est d’autant plus forte que les atomes sont proches les uns des autres, et peut perturber considérablement le comportement radiatif de l’ensemble atomique, voire empêcher l’excitation de plusieurs atomes à la fois. Par exemple, un nuage d’atomes dense peut se comporter comme une cavité sans miroirs : le laser peut exciter certains modes de rayonnement particuliers, qui rayonnent chacun avec sa fréquence et son taux de relaxation propres, différents de ceux d’un atome individuel. Certains de ces modes collectifs sont super-radiants (le nuage réémet l’excitation emmagasinée plus rapidement que ne le ferait un atome individuel), d’autres sont au contraire sub-radiants.Afin d’étudier ces phénomènes, notre équipe a construit une expérience qui permet de piéger entre 1 et ~500 atomes froids de rubidium dans un piège laser de dimensions ~1µm³. Nous excitons les atomes près de la transition à 780 nm. La taille du nuage, de l’ordre de 100 nm, est proche de la longueur d'onde réduite. Enfin, l’élargissement Doppler des transitions atomiques est négligeable (atomes froids). La situation est donc quasi-idéale pour l’observation de modes de rayonnement collectifs. Nous avons observé expérimentalement les effets de ces interactions, mais l'accord avec la théorie ne semble être, jusqu'à présent, que qualitatif (malgré nos efforts pour nous soustraire de la structure interne des atomes).Nous avons donc décidé de construire une deuxième version du dispositif expérimental. Cette ambitieuse deuxième version dispose à présent de deux axes optiques haute résolution. En plus de résoudre certains problèmes expérimentaux présent dans la précédente version, elle ouvre la voie à de nouvelles expériences pour étudier les interactions dipolaires: nouveaux régimes de densité et nouvelles configurations atomiques comme les chaînes d'atomes