title: Ruminal degradation of cell wall associated nitrogenous compounds of several (15) N-labelled feeds.
abstract: BACKGROUND
  Ruminal in situ effective degradability (ED) of dry matter (DM), neutral (NDF) and acid (ADF) detergent fibres, total-N and NDF (NDIN) and ADF (ADIN) bound-N in sunflower seed (SS), wheat grain (WG) and wheat straw (WS) were measured in three ruminally cannulated sheep, correcting microbial N-contamination using the (15) N dilution technique modified to consider the (15) N supply to adherent bacteria.
  
  
  RESULTS
  The lack of correction for N-contamination under-evaluated ED estimates in 1.52% (total-N), 28.0% (NDIN) and 33.3% (ADIN) in SS and in 1.02% (total-N) and 4.43% (NDIN) in WG. In the remaining cases, this contamination prevented establishing apparent degradation kinetics and, therefore, errors were not measured. Microbial corrected ED estimates in SS were higher in total-N (0.917) than in NDIN (0.559) and ADIN (0.520), which showed similar values. This behaviour was also shown in WS (0.670, 0.386 and 0.426, respectively), whereas decreasing values were shown from total-N (0.917) to NDIN (0.830) and ADIN (0.482) in WG.
  
  
  CONCLUSIONS
  Results confirm that NDF and ADF procedures failed to remove large fractions of particle adherent microorganisms, under-evaluating the ED of NDIN and ADIN. Degradation of NDIN represented a significant part of the degraded N, whereas ADIN contribution was only negligible in WG. © 2015 Society of Chemical Industry.
authors.affiliation: Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040, Madrid, Spain.
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Vanegas
authors.affiliation: Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040, Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Arroyo
authors.affiliation: Departamento de Producción Agraria, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Ciudad Universitaria, 28040, Madrid, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: González
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001419:Bacteria / Q000302:isolation & purification; D004032:Diet / Q000662:veterinary*; D005516:Food Microbiology; D009587:Nitrogen Isotopes / Q000378:metabolism*; D012417:Rumen / Q000378:metabolism*; D012756:Sheep / Q000502:physiology*
chemical_list: D009587:Nitrogen Isotopes
keywords: cell wall-bound N; feed evaluation; microbial contamination; ruminal degradability; sheep