249 research outputs found
Interest and limitations of techniques replacing experimental surgery on the digestive tract of herbivores
The study of digestion in herbivores often requires the surgical setting of cannulas on different parts
of the digestive tract. These techniques helped to improve rapidly and substantially our knowledge
of the mechanisms and extent of the digestive processes. The main non-surgical techniques are described
and their interest and limitations are evaluated. These techniques include various in sacco and in vitro
(artificial rumen) methods, measurements in slaughtered animals, rumenocentesis, analyses of
faeces and biological fluids, and meta-analyses and modelling. The author concludes that these alternative
techniques can replace only partially the use of digestive surgery.L'Ă©tude de la digestion chez
les herbivores fait souvent appel Ă des techniques chirurgicales consistant Ă poser des
canules sur différentes parties du tube digestif. Ces techniques ont permis des progrÚs
rapides et importants dans la connaissance et la quantification des processus digestifs. Les
principales mĂ©thodes ne faisant pas appel Ă la chirurgie sont dĂ©crites et leurs intĂ©rĂȘts et
leurs limites évalués: différentes méthodes in sacco et in vitro (rumen artificiel), mesures
chez des animaux abattus, ruminocentĂšse, analyses des fĂšces ou de liquides biologiques, et
approches par méta-analyse ou modélisation. L'auteur conclut que ces méthodes alternatives
peuvent remplacer seulement en partie les techniques de chirurgie digestive
Métabolisme ruminal et digestion des acides gras longs chez le ruminant : le point des connaissances récentes
La maßtrise de la composition en Acides Gras (AG) des produits animaux est l'une des composantes de l'amélioration de leur qualité nutritionnelle, passant par exemple par une diminution des AG saturés réputés athérogÚnes et une augmentation des AG polyinsaturés de la série n-3 (oméga-3) dans les produits de ruminants. Chez les ruminants, les AG longs ingérés subissent des transformations structurales importantes dans le rumen, principalement des réactions de saturation, trans isomérisation et conjugaison des doubles liaisons.
La composition des AG arrivant dans l'intestin grĂȘle puis absorbĂ©s est donc complĂštement diffĂ©rente de celle des AG ingĂ©rĂ©s, avec de plus l'apparition de trĂšs nombreux isomĂšres issus de l'action du microbiote ruminal sur les AG. Ces phĂ©nomĂšnes sont trĂšs Ă©tudiĂ©s depuis longtemps, mais les rĂ©cents progrĂšs dans l'analyse des AG d'une part et dans l'Ă©tude du microbiote ruminal d'autre part ont permis d'affiner les connaissances depuis quelques annĂ©es. Cet article prĂ©sente l'Ă©tat des connaissances sur les mĂ©canismes ruminaux de lipolyse et de biohydrogĂ©nation des AG insaturĂ©s alimentaires dans le rumen (y compris des donnĂ©es rĂ©centes sur les AG Ă 20 et 22 carbones), l'ampleur de la biohydrogĂ©nation et l'effet des facteurs alimentaires, les flux et la composition des AG arrivant dans l'intestin, la protection des lipides contre la biohydrogĂ©nation et l'absorption intestinale des AG. Ces connaissances permettent de mieux comprendre et prĂ©voir le devenir des AG ingĂ©rĂ©s et donc potentiellement de mieux maĂźtriser la composition en AG des produits de ruminants
Engraissement de taurillons de race française frisonne pie noire en Guadeloupe. Utilisation comparée d'aliments à base de son et de céréales
En Guadeloupe, 2 groupes de 12 et 9 taurillons frisons ont reçu entre le sevrage et l'abattage Ă 15 mois de l'herbe hachĂ©e (Pangola) en quantitĂ© limitĂ©e et un aliment concentrĂ© ad libitum, soit hautement Ă©nergĂ©tique (66 p. 100 cĂ©rĂ©ales, 10 p.100 tourteau d'arachide, 21 p. 100 luzerne dĂ©shydratĂ©e), soit moins Ă©nergĂ©tique (85 p. 100 son de blĂ©, 10 p. 100 mĂ©lasse de canne Ă sucre, 1,5 p. 100 urĂ©e). Les gains moyens journaliers (888 et 854 g) et les consommations journaliĂšres d'aliment concentrĂ© (6,2 et 6,0 kg) n'ont pas Ă©tĂ© significativement diffĂ©rentes. Le rĂ©gime moins Ă©nergĂ©tique a donc Ă©tĂ© utilisĂ© plus efficacement. Les consommations et croissances obtenues avec le rĂ©gime riche en Ă©nergie sont infĂ©rieures Ă celles qui ont Ă©tĂ© enregistrĂ©es avec ce mĂȘme rĂ©gime sur le mĂȘme gĂ©notype en milieu tempĂ©r
The Structural and Functional Capacity of Ruminal and Cecal Microbiota in Growing Cattle Was Unaffected by Dietary Supplementation of Linseed Oil and Nitrate
peer-reviewedMicroorganisms in the digestive tract of ruminants differ in their functionality and ability to use feed constituents. While cecal microbiota play an important role in post-rumen fermentation of residual substrates undigested in the rumen, limited knowledge exists regarding its structure and function. In this trial we investigated the effect of dietary supplementation with linseed oil and nitrate on methane emissions and on the structure of ruminal and cecal microbiota of growing bulls. Animals were allocated to either a CTL (control) or LINNIT (CTL supplemented with 1.9% linseed and 1.0% nitrates) diet. Methane emissions were measured using the GreenFeed system. Microbial diversity was assessed using amplicon sequencing of microbial genomic DNA. Additionally, total RNA was extracted from ruminal contents and functional mcrA and mtt genes were targeted in amplicon sequencing approach to explore the diversity of functional gene expression in methanogens. LINNIT had no effect on methane yield (g/kg DMI) even though it decreased methane production by 9% (g/day; P < 0.05). Methanobrevibacter- and Methanomassiliicoccaceae-related OTUs were more abundant in cecum (72 and 24%) compared to rumen (60 and 11%) irrespective of the diet (P < 0.05). Feeding LINNIT reduced the relative abundance of Methanomassiliicoccaceae mcrA cDNA reads in the rumen. Principal component analysis revealed significant differences in taxonomic composition and abundance of bacterial communities between rumen and cecum. Treatment decreased the relative abundance of a few Ruminococcaceae genera, without affecting global bacterial community structure. Our research confirms a high level of heterogeneity in species composition of microbial consortia in the main gastrointestinal compartments where feed is fermented in ruminants. There was a parallel between the lack of effect of LINNIT on ruminal and cecal microbial community structure and functions on one side and methane emission changes on the other. These results suggest that the sequencing strategy used here to study microbial diversity and function accurately reflected the absence of effect on methane phenotypes in bulls treated with linseed plus nitrate.This experiment is a part of a large collaborative project led by INRA granted by 11 companies: Adisseo France SAS, Agrial, Apis Gene, Deltavit, DSM Nutritional Products AG, Institut de l'Elevage, Lallemand, Moy Park Beef Orléans, Neovia, Techna France Nutrition, Valorex. This project aims to reduce enteric methane emission by nutrition. MP was the recipient of a PHC Ulysses travel scholarship to Ireland, provided by the French ministry of Foreign Affairs and International Development (MinistÚres des Affaires EtrangÚres et du Développement International, MAEDI) and the ministry of National Education, Higher Education, and Research (MinistÚre de l'Education Nationale, de l'Enseignement Supérieur et de la Recherche, MENESR). EM was the recipient of a FACCE-JPI scholarship
La viande du futur sera-t-elle produite in vitro ?
La production de viande artificielle par culture de cellules est proposĂ©e par certains scientifiques comme une des solutions pour rĂ©pondre aux grands enjeux de lâĂ©levage : i) rĂ©duire le mal-ĂȘtre supposĂ© des animaux dans les Ă©levages modernes, voire ne pas tuer les animaux pour les manger, ii) rĂ©duire la possible dĂ©gradation de lâenvironnement par lâĂ©levage et iii) rĂ©duire la faim dans le monde en augmentant le niveau des ressources protĂ©iques alimentaires. La viande artificielle supprimerait en effet le mal-ĂȘtre supposĂ© des animaux liĂ© Ă lâĂ©levage et permettrait de ne pas abattre les animaux pour les manger. Lâimpact environnemental de la viande artificielle est difficile Ă Ă©valuer en lâabsence de donnĂ©es sur le fonctionnement dâune usine de production. La viande artificielle prĂ©senterait toutefois un intĂ©rĂȘt modĂ©rĂ© pour rĂ©duire les gaz Ă effet de serre et la pollution par les nitrates, un intĂ©rĂȘt limitĂ© quant Ă lâutilisation des Ă©nergies fossiles, voire trĂšs limitĂ© pour limiter les besoins en eau, mais elle libĂ©rerait des terres cultivables. Elle entraĂźnerait probablement dans lâeau des rĂ©sidus de molĂ©cules de synthĂšse. De nombreux experts estiment que les causes de la malnutrition actuelle de certaines populations sont multiples et ne sont pas directement liĂ©es Ă un manque de ressources alimentaires. Bien que la culture de cellules soit couramment pratiquĂ©e en laboratoire, il existe des verrous techniques importants Ă lever pour une production Ă grande Ă©chelle, tels que le coĂ»t rĂ©dhibitoire des technologies actuelles et le manque de ressemblance du produit obtenu Ă de la viande issue dâanimaux. Sur le plan nutritionnel, la viande artificielle ne prĂ©sente pas dâavantage particulier par rapport Ă un autre aliment Ă©laborĂ© Ă partir de lâensemble des nutriments nĂ©cessaires Ă sa production. Les critĂšres dâacceptabilitĂ© de la viande artificielle renvoient, dâune part, Ă des questions dâordre moral ou Ă©thique concernant la technologie et les inquiĂ©tudes quâelle soulĂšve, et dâautre part, Ă des considĂ©rations classiques relatives aux produits alimentaires (prix, qualitĂ©, naturalitĂ©...). Par le passĂ©, les expĂ©riences de substitution des protĂ©ines animales par des produits analogues ont Ă©chouĂ© en raison, notamment, de contraintes Ă©conomiques, du temps nĂ©cessaire pour lâĂ©ventuelle acceptation des produits par les consommateurs et pour la dĂ©livrance des autorisations de mise sur le marchĂ©. Face aux questionnements importants concernant lâĂ©levage, la production de viande artificielle ne prĂ©sente pas aujourdâhui dâavantages majeurs par comparaison Ă la viande naturelle ou Ă dâautres alternatives possibles telles que rĂ©Ă©quilibrer notre alimentation en diversifiant les sources de protĂ©ines vĂ©gĂ©tales et animales, ou encore dĂ©velopper des systĂšmes dâĂ©levage plus respectueux des animaux et de lâenvironnement
Effectiveness of Interventions to Modulate the Rumen Microbiota Composition and Function in Pre-ruminant and Ruminant Lambs
Modulating the assembly of the ruminal microbiota might have practical implications in production. We tested how an early-life dietary intervention in lambs influences the diversity and function of the ruminal microbiota during and after the intervention. Microbiota resilience during a repeated dietary intervention was also tested. The treatment, aiming to mitigate enteric methane emissions, combined garlic essential oil and linseed oil. Fifty-six lambs and their dams were allocated to two groups and treatment (T1) or placebo (C1) was drenched from birth until 10 weeks of life. Lambs were weaned at 8 weeks. From 16 to 20 weeks, lambs in each group were divided in two subgroups that received (T1âT2 and C1âT2) or not (T1âC2 and C1âC2) the same treatment. Measurements were done at 8, 14, and 20 weeks. Average daily gain was similar between groups. Methane production was reduced by treatment at 8 and 20 weeks but at 14 weeks it was similar between C1 and T1. Interestingly, early-life treated lambs displayed a numerical increase (P = 0.12) in methane emissions at 20 weeks compared with non-treated lambs. Concentration of VFA was not affected by the intervention at 8 or 14 weeks but a lower concentration was observed in T2 lambs compared with C2 at week 20. Metataxonomics (rRNA gene) revealed differences in archaeal communities between groups of lambs when treatment was applied (weeks 8 and 20); whereas, in accord with methane emissions, these differences disappeared when treatment was discontinued (week 14). Protozoal community structure was not affected by treatment. In contrast, bacterial community structure differed between treated and non-treated lambs during and after the intervention. Rumen and urine LC-MS and NMR metabolomics at week 20 separated C2 from T2 lambs and correlation analysis highlighted interactions between microbes and metabolites, notably that of methylated compounds and Methanomassiliicocceae methanogens. This study demonstrates that a long-term early-life intervention induced modifications in the composition of the rumen bacterial community that persisted after the intervention ceased with little or no effect on archaeal and protozoal communities. However, there was no persistency of the early-life intervention on methanogenesis indicating resilience for this function
Identifying cost-competitive greenhouse gas mitigation potential of French agriculture
The agriculture, forestry and other land use sector are responsible for 24% (10â12 Pg CO2e per year) of anthropogenic greenhouse gas (GHG) emissions worldwide, with concomitant opportunities for mitigation. A scientific panel used deliberative methods to identify ten technical measures comprising 26 sub-measures to reduce GHG emissions from agriculture in France. Their abatement potential and cost are compared. The proposed measures concern nitrogen (N) management, management practices that increase carbon stocks in soils and biomass, livestock diets, and energy production and consumption on farms. Results show that the total abatement potential can be divided into three parts. One third of the cumulated abatement potential corresponds to sub-measures that can be implemented at a negative technical cost. These sub-measures focus on increased efficiency in input use including N fertilisers, animal feed and energy. The second third are sub-measures with moderate cost (âŹ25 per metric Mg of avoided CO2e). These require investment with no direct financial return, the purchase of particular inputs, dedicated labour time or involve production losses. Assuming additivity, the cumulated abatement is 32.3 Tg CO2e per year in 2030, but only 10 Tg (i.e. 10% of current agricultural emissions) when calculated under current inventory rules. This study confirms that a significant abatement potential exists in the agricultural sector, with two thirds of this potential at low or even negative cost. This is likely to be an underestimated as it is based on a status quo of the current agricultural system. Results also emphasise the need to upgrade inventory rules so that efforts to reduce emissions can be accounted for
Influence of drastic underfeeding on ruminal digestion in sheep
The effect of severe underfeeding on ruminal digestion was studied in sheep. Six wethers
fitted with ruminal cannulae were used in a replicated 3 3 Latin square design.
They received the same hay at three intake levels corresponding to energy maintenance
requirements (M), 60% (0.6 M) and 20% (0.2 M) of these requirements. Fibre digestibility
was higher at 0.2 M than at the other two levels. Ruminal neutral detergent fibre
retention time did not vary between M and 0.6 M, but increased at 0.2 M. When intake
was low, rumen fill decreased and contents became very liquid. No variation in in
situ microbial activity or in enzymatic activities of microbial polysaccharidases or
glycosidases was observed. Protozoa concentration decreased with intake, but total
bacterial mass did not vary when intake decreased. Adherent bacterial mass expressed
as a proportion of solid phase was higher at low intake. Volatile fatty acid pattern
showed a shift from butyrate towards acetate when intake decreased. It is concluded
that (i) changes in digestion are slight between M and 0.6 M, and (ii) microbial
activity is not impaired at very low intake level.Effet d'une trĂšs forte sous-alimentation sur la digestion ruminale chez le mouton.
Six béliers castrés munis de canules du rumen ont été utilisés dans un double carré
latin 3 3. Ils ont reçu le mĂȘme foin Ă trois niveaux d'ingestion correspondant aux
besoins énergétiques d'entretien (E), à 60 % (0,6 E) et 20 % (0,2 E) de ces besoins.
La digestibilité des parois végétales a été plus élevée à 0,2 E qu'aux deux autres
niveaux. Le temps de rétention des parois dans le rumen n'a pas varié entre E et 0,6 E,
mais a été plus élevé à 0,2 E. Lorsque le niveau d'ingestion était bas, le remplissage
du rumen a été plus faible et le contenu plus liquide. Aucune variation de l'activité
microbienne in situ ou des activités des polysaccharidases et glycosidases microbiennes
n'a été observée. La concentration des protozoaires a diminué avec le niveau d'ingestion,
mais pas la masse totale de bactéries. La masse de bactéries adhérentes en proportion
de la phase solide a été plus élevée à bas niveau d'ingestion. Le profil des acides gras
volatils a montré une réduction du butyrate au profit de l'acétate à bas niveau
d'ingestion. En conclusion, les modifications de la digestion ont été faibles entre
E et 0,6 E, et l'activité microbienne n'a pas été réduite à trÚs bas niveau d'ingestion
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