title: The effects of a ration change from a total mixed ration to pasture on rumen fermentation, volatile fatty acid absorption characteristics, and morphology of dairy cows.
abstract: To investigate the effect of the change from a concentrate and silage-based ration (total mixed ration, TMR) to a pasture-based ration, a 10-wk trial (wk 1-10) was performed, including 10 rumen- and duodenum-fistulated German Holstein dairy cows (182±24 d in milk, 23.5±3.5kg of milk/d; mean ± standard deviation). The cows were divided in either a pasture group (PG, n=5) or a confinement group (CG, n=5). The CG stayed on a TMR-based ration (35% corn silage, 35% grass silage, 30% concentrate; dry matter basis), whereas the PG was gradually transitioned from a TMR to a pasture-based ration (wk 1: TMR only; wk 2: 3 h/d on pasture wk 3 and 4: 12 h/d on pasture wk 5-10: pasture only). Ruminal pH, volatile fatty acids (VFA), NH3-N, and lipopolysaccharide (LPS) concentrations were measured in rumen fluid samples collected medially and ventrally on a weekly basis. Ruminal pH was continuously recorded during 1 to 4 consecutive days each week using ruminal pH measuring devices. In wk 1, 5, and 10, rumen contents were evacuated and weighed, papillae were collected from 3 locations in the rumen, and subsequently a VFA absorption test was performed. In the PG, mean rumen pH and molar acetate proportions decreased, and molar butyrate proportions increased continuously over the course of the trial, which can most likely be ascribed to an increased intake of rapidly fermentable carbohydrates. During the first weeks on a full grazing ration (wk 5-7), variation of rumen pH decreased, and in wk 5 a lower rumen content, papillae surface area, and potential for VFA absorption were observed. In wk 8 to 10, variation of rumen pH and total VFA concentrations increased again, and acetate/propionate ratio decreased. In wk-10 rumen content, papillae area and VFA absorption characteristics similar to initial levels were observed. Although continuous rumen pH assessments and LPS concentrations did not reveal an increased risk for subacute rumen acidosis (SARA) during the adaption period, histopathology of rumen papillae and potential for VFA absorption indicated a possible risk for rumen health. An increased risk for SARA was observed in wk 9 and 10 in the PG, but rumen LPS concentrations and histopathology were not adversely affected. Results of the present study suggest that after behavioral and metabolic adaptation to the transition from a TMR to a pasture-based ration, no adverse effects on rumen morphology and absorption capacity occurred, although rumen pH after adaptation to pasture indicated increased risk of SARA.
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Bundesallee 50, 38116 Brunswick, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schären
authors.affiliation: Institute of Animal Science, University of Hohenheim, Emil-Wolff-Str. 10, 70599 Stuttgart, Germany.
authors.forename: G M
authors.initials: GM
authors.lastname: Seyfang
authors.affiliation: Institute of Animal Science, University of Hohenheim, Emil-Wolff-Str. 10, 70599 Stuttgart, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Steingass
authors.affiliation: Animal Nutrition Group, Wageningen University, De Elst 1, 6708WD Wageningen, the Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Dieho
authors.affiliation: Animal Nutrition Group, Wageningen University, De Elst 1, 6708WD Wageningen, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Dijkstra
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Bundesallee 50, 38116 Brunswick, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Hüther
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Bundesallee 50, 38116 Brunswick, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Frahm
authors.affiliation: Institute of Pathology, University of Veterinary Medicine Hanover, Bünteweg 17, 30559 Hannover, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Beineke
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Bundesallee 50, 38116 Brunswick, Germany.
authors.forename: D
authors.initials: D
authors.lastname: von Soosten
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Bundesallee 50, 38116 Brunswick, Germany. Electronic address: Ulrich.Meyer@fli.bund.de.
authors.forename: U
authors.initials: U
authors.lastname: Meyer
authors.affiliation: Department of Physiology, University of Veterinary Medicine Hanover, Bischofsholer Damm 15, 30173 Hannover, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Breves
authors.affiliation: Institute of Animal Nutrition, Friedrich-Loeffler-Institute, Federal Research Institute for Animal Health, Bundesallee 50, 38116 Brunswick, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Dänicke
mesh_terms: D065567:Absorption, Physiological; D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D002417:Cattle / Q000033:anatomy & histology / Q000502:physiology*; D003612:Dairying / Q000379:methods*; D004032:Diet / Q000662:veterinary*; D005232:Fatty Acids, Volatile / Q000378:metabolism; D005260:Female; D005858:Germany; D006863:Hydrogen-Ion Concentration; D008070:Lipopolysaccharides / Q000032:analysis; D011897:Random Allocation; D012417:Rumen / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology
chemical_list: D005232:Fatty Acids, Volatile; D008070:Lipopolysaccharides
keywords: pasture; ration change; rumen papillae morphology; rumen volatile fatty acid absorption characteristics