title: Fermentation, degradation and microbial nitrogen partitioning for three forage colour phenotypes within anthocyanidin-accumulating Lc-alfalfa progeny.
abstract: BACKGROUND
  Alfalfa has the disadvantage of having a rapid initial rate of protein degradation, which results in pasture bloat, low efficiency of protein utilisation and excessive nitrogen (N) pollution into the environment for cattle. Introducing a gene that stimulates the accumulation of monomeric/polymeric anthocyanidins might reduce the ruminal protein degradation rate (by fixing protein and/or direct interaction with microbes) and additionally reduce methane emission. The objectives of this study were to evaluate in vitro fermentation, degradation and microbial N partitioning of three forage colour phenotypes (green, light purple-green (LPG) and purple-green (PG)) within newly developed Lc-progeny and to compare them with those of parental green non-transgenic (NT) alfalfa.
  
  
  RESULTS
  PG-Lc accumulated more anthocyanidin compared with Green-Lc (P < 0.05), with LPG-Lc intermediate. Volatile fatty acids and potentially degradable dry matter (DM) and N were similar among the four phenotypes. Gas, methane and ammonia accumulation rates were slower for the two purple-Lc phenotypes compared with NT-alfalfa (P < 0.05), while Green-Lc was intermediate. Effective degradable DM and N were lower in the three Lc-phenotypes (P < 0.05) compared with NT-alfalfa. Anthocyanidin concentration was negatively correlated (P < 0.05) with gas and methane production rates and effective degradability of DM and N.
  
  
  CONCLUSIONS
  The Lc-alfalfa phenotypes accumulated anthocyanidin. Fermentation and degradation parameters indicated a reduced rate of fermentation and effective degradability for both purple anthocyanidin-accumulating Lc-alfalfa phenotypes compared with NT-alfalfa.
authors.affiliation: Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK, Canada. arjan.jonker@agresearch.co.nz
authors.forename: Arjan
authors.initials: A
authors.lastname: Jonker
authors.forename: Margaret Y
authors.initials: MY
authors.lastname: Gruber
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Wang
authors.forename: Nelmy
authors.initials: N
authors.lastname: Narvaez
authors.forename: Bruce
authors.initials: B
authors.lastname: Coulman
authors.forename: John J
authors.initials: JJ
authors.lastname: McKinnon
authors.forename: David A
authors.initials: DA
authors.lastname: Christensen
authors.forename: Arash
authors.initials: A
authors.lastname: Azarfar
authors.forename: Peiqiang
authors.initials: P
authors.lastname: Yu
mesh_terms: D000641:Ammonia / Q000378:metabolism; D000821:Animal Feed / Q000009:adverse effects / Q000032:analysis*; D000818:Animals; D000872:Anthocyanins / Q000378:metabolism*; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control; D003433:Crosses, Genetic; D004063:Digestion; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005285:Fermentation; D005740:Gases / Q000378:metabolism; D007700:Kinetics; D000455:Medicago sativa / Q000235:genetics / Q000378:metabolism*; D008697:Methane / Q000378:metabolism; D008954:Models, Biological; D058458:Nitrogen Cycle; D010860:Pigments, Biological / Q000235:genetics / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D055550:Protein Stability; D012417:Rumen / Q000382:microbiology*
chemical_list: D000872:Anthocyanins; D005232:Fatty Acids, Volatile; D005740:Gases; D010860:Pigments, Biological; D010940:Plant Proteins; D000641:Ammonia; D008697:Methane