Composition chimique, dégradabilité in sacco et produits de fermentation in vitro de la fétuque élevée (Festuca arundinacea

Objectifs : En vue d’une sélection pour une utilisation comme aliment pour bétail, vingt quatre écotypes de fétuque élevée (Festuca arundinacea) provenant du milieu naturel du nord de la Belgique ont été étudiés afin d’en déterminer la valeur nutritionnelle.Méthodologie et Résultats : La composition chimique, la dégradabilité in sacco et les incubations in vitro ont été réalisés. Un mouton adulte fistulé au niveau du rumen a été utilisé pour la détermination de la dégradabilité in sacco des écotypes et les incubations in vitro. La teneur moyenne en MAT (8,0% MS) des 24 écotypes étudiés est faible. Les écotypes de Festuca arundinacea présentent en moyenne une meilleure dégradabilité potentielle (a + b) (82,7%) que les fourrages tropicaux Pennisetum purpureum (64,9%) et Tripsacum laxum (66,8%) mais moindre que les fourrages tempérés (Lolium perenne : 90,5%). Festuca arundinacea a présenté une production élevée de propionate (234.7 Gmol/mmol AGV totaux).Conclusion : Les meilleurs de la collection de 24 écotypes de F. arundinacea ont été identifiés pour une utilisation comme aliment pour bétail. Les teneurs en MAT trouvées pour la fétuque élevée sont comparables à celles des fourrages tropicaux qui sont généralement plus pauvres en protéine que les fourrages tempérés ; ce qui représente un handicap pour leur ingestion volontaire. Ces résultats impliquent d’une part qu’il faut une supplémentation en azote pour les pâturages de Festuca arundinacea et d’autre part l’exploitation des pâturages à la fétuque élevée au stade avant frutification. Par ailleurs, la culture en association de fétuque élevée et légumineuses est également une solution envisageable. Une variabilité a été notée entre les écotypes de Festuca arundinacea qui en moyenne présentent une meilleure dégradabilité que les fourrages tropicaux, mais moindres que les fourrages tempérés. Cet avantage de la fétuque élevée sur les fourrages tropicaux se consolide par une production élevée d’acide propionique et faible d’acide acétique comparables à celles des fourrages tempérés ; ce qui est très intéressant car le propionate peut générer du glucose, un des facteurs limitant pour la production laitière.Mots clés: Festuca arundinacea, écotype, azote ammoniacal, dégradabilité in sacco, méthane, acides gras volatile

Epithelial, metabolic and innate immunity transcriptomic signatures differentiating the rumen from other sheep and mammalian gastrointestinal tract tissues

Background. Ruminants are successful herbivorous mammals, in part due to their specialized forestomachs, the rumen complex, which facilitates the conversion of feed to soluble nutrients by micro-organisms. Is the rumen complex a modified stomach expressing new epithelial (cornification) and metabolic programs, or a specialised stratified epithelium that has acquired new metabolic activities, potentially similar to those of the colon? How has the presence of the rumen affected other sections of the gastrointestinal tract (GIT) of ruminants compared to non-ruminants? Methods. Transcriptome data from 11 tissues covering the sheep GIT, two stratified epithelial and two control tissues, was analysed using principal components to cluster tissues based on gene expression profile similarity. Expression profiles of genes along the sheep GIT were used to generate a network to identify genes enriched for expression in different compartments of the GIT. The data from sheep was compared to similar data sets from two non-ruminants, pigs (closely related) and humans (more distantly related). Results. The rumen transcriptome clustered with the skin and tonsil, but not the GIT transcriptomes, driven by genes from the epidermal differentiation complex, and genes encoding stratified epithelium keratins and innate immunity proteins. By analysing all of the gene expression profiles across tissues together 16 major clusters were identified. The strongest of these, and consistent with the high turnover rate of the GIT, showed a marked enrichment of cell cycle process genes (P = 1.4 E−46), across the whole GIT, relative to liver and muscle, with highest expression in the caecum followed by colon and rumen. The expression patterns of several membrane transporters (chloride, zinc, nucleosides, amino acids, fatty acids, cholesterol and bile acids) along the GIT was very similar in sheep, pig and humans. In contrast, short chain fatty acid uptake and metabolism appeared to be different between the species and different between the rumen and colon in sheep. The importance of nitrogen and iodine recycling in sheep was highlighted by the highly preferential expression of SLC14A1-urea (rumen), RHBG-ammonia (intestines) and SLC5A5-iodine (abomasum). The gene encoding a poorly characterized member of the maltase-glucoamylase family (MGAM2), predicted to play a role in the degradation of starch or glycogen, was highly expressed in the small and large intestines. Discussion. The rumen appears to be a specialised stratified cornified epithelium, probably derived from the oesophagus, which has gained some liver-like and other specialized metabolic functions, but probably not by expression of pre-existing colon metabolic programs. Changes in gene transcription downstream of the rumen also appear have occurred as a consequence of the evolution of the rumen and its effect on nutrient composition flowing down the GIT

Prevalence of Brucellosis among Women Presenting with Abortion/Stillbirth in Huye, Rwanda

The incidence of human brucellosis is not documented in Rwanda despite several reports on the disease in cattle. Because brucellosis has been associated with abortion, the aim of this study was to investigate the prevalence of positive serology in women presenting with abortion and/or stillbirth. The study was done in Huye District, in the Southern Province of Rwanda, and the patients were recruited from both the University Teaching Hospital of Butare (CHUB) and Kabutare District Hospital. Serum samples were collected and the Rose Bengal plate test (RBPT) was performed on each sample. A questionnaire was also used to investigate potential contacts with animals and/or consumption of raw milk. A total of 60 women were recruited and 15 (i.e., 25%) were Brucella seropositive. The questionnaire showed that those with seropositivity either were in contact with domestic animals (cattle, goat, or sheep) or were consuming raw cow’s milk. Human brucellosis appears to be of public health importance in Rwanda and more attention should be drawn on the disease. The current study provides a basis for larger studies to establish the incidence of human brucellosis in Rwanda. More mechanistic studies will also demonstrate the pathogenicity of Brucella in human placentas

Degradation of methionine by rumen contents in vitro and efficiency of its protection.

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