title: Evaluation of the effects of dietary particle fractions on fermentation profile and concentration of microbiota in the rumen of dairy cows fed grass silage-based diets.
abstract: The study evaluated the effects of three different theoretical particle lengths (TPL) of grass silage on the distribution of particle fractions of the diet and the resulting effects on fermentation profile and concentrations of protozoa and mixed bacterial mass in the rumen of three lactating Holstein cows fed total mixed rations (45% grass silage, 5% grass hay and 50% concentrate) ad libitum. Decreasing TPL of grass silage (long, medium, short) reduced particles retained on the 19-mm sieve of the Penn State Particle Separator, while particle fractions from 8 mm to 19 mm and smaller than 8 mm were increased. Different TPL did not affect pH and the concentration of volatile fatty acids in the rumen. However, lowering the TPL from long to medium increased significantly the bicarbonate concentration, acetate proportion and protozoal number in the rumen, whereas the proportion of bacterial protein in ruminal digesta and its amino acid concentration were significantly increased by the short TPL. For the current feeding conditions, it can be concluded that increasing the fraction of particles between 8 and 19 mm and probably even the fraction below 8 mm by decreasing TPL of grass silage do not adversely affect rumen conditions and can be beneficial in terms of optimising concentration and activity of ruminal microbiota in high-yielding dairy cows.
authors.affiliation: University of Hohenheim, Institute of Animal Nutrition, Stuttgart, Germany.
authors.forename: Qendrim
authors.initials: Q
authors.lastname: Zebeli
authors.forename: Myqerem
authors.initials: M
authors.lastname: Tafaj
authors.forename: Benjamin
authors.initials: B
authors.lastname: Junck
authors.forename: Dominik
authors.initials: D
authors.lastname: Mansmann
authors.forename: Herbert
authors.initials: H
authors.lastname: Steingass
authors.forename: Winfried
authors.initials: W
authors.lastname: Drochner
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001421:Bacteria, Anaerobic / Q000254:growth & development / Q000378:metabolism; D018533:Biomass; D002417:Cattle / Q000378:metabolism*; D004063:Digestion; D056890:Eukaryota / Q000254:growth & development / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000032:analysis / Q000378:metabolism; D005260:Female; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D006109:Poaceae / Q000033:anatomy & histology / Q000737:chemistry; D012417:Rumen / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology / Q000469:parasitology; D012820:Silage
chemical_list: D005232:Fatty Acids, Volatile