title: Effect of forage physical form on chewing activity, dry matter intake, and rumen function of dairy cows in early lactation.
abstract: To examine the effects of reducing forage particle size on production, chewing, and digesta kinetic parameters in early lactation, 42 Holstein cows (9 ruminally cannulated) were assigned 14 d postpartum to one of three experimental diets with concentrate: alfalfa haylage: alfalfa pellets ratio of A) 60:40:0;B) 60:28:12; and C) 60:12:28 on a DM basis. The trial ran through the 12th wk postpartum, and measurements of chewing activity and rumen parameters were made during the 4th, 8th, and 12th wk postpartum. Dry matter intake (kg/d), milk production (kg/d), and milk fat percentage for diets A, B, and C were 23.1, 23.0, 18.8; 33.7, 35.5, 31.8; and 3.1, 2.9, 2.6, respectively. Rumen parameters and chewing activities were linearly related to haylage in the diet. Ruminal fluid dilution rate (%/h), volume (L), and outflow (L/d), rumination (min/d), total chewing (min/d), total chewing (min/kg DM intake), ruminal acetate (molar %), and NDF digestibility (%) were 16.6, 13.8, 10.0; 62, 58, 54; 243, 193, 137; 437; 367, 204; 649, 566, 376; 28.2, 24.1, 20.0; 58.6, 56.3, 53.8; and 32, 37, 23, respectively. These results suggest that dairy cattle in early lactation require a minimum amount of effective fiber to optimize production and intake. This requirement was met when 28%, but not 12%, of dietary DM was alfalfa haylage.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana 61801.
authors.forename: S T
authors.initials: ST
authors.lastname: Woodford
authors.forename: M R
authors.initials: MR
authors.lastname: Murphy
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004043:Dietary Fiber / Q000378:metabolism*; D004063:Digestion; D005260:Female; D007774:Lactation / Q000502:physiology*; D008409:Mastication; D010316:Particle Size; D011247:Pregnancy; D012417:Rumen / Q000502:physiology*