title: Effects of dietary neutral detergent fiber concentration and supplementary long hay on chewing activities and milk production of dairy cows.
abstract: Effects of dietary NDF concentration on chewing and productivity were assessed using silage-based diets with and without supplemental long hay. Twelve Holstein cows (125 d postpartum) were used in a double 6 x 6 Latin square to evaluate six diets formulated using high moisture shelled corn and alfalfa silage (37% DM, 23% CP, 48% NDF) to provide three concentrations of NDF: 26, 30, and 34%. At each concentration, an alternative diet was formulated by substituting 15% of the silage DM with an equivalent amount of long alfalfa grass hay (14% CP, 61% NDF). Cows were fed at 85% of ad libitum intake, and ingredients were allocated separately. Increasing NDF decreased milk yield from 20.8 to 19.9 and 19.1 kg/d, for 26, 30, and 34%, respectively. Supplementing diets with hay increased milk production by .7 kg/d, although milk fat content was not affected. Increasing NDF resulted in a quadratic increase in ruminating and total chewing time from 344 and 558 for 26% NDF, to 413 and 651 for 30%, and 414 and 674 min/d for 34%, respectively. Added hay did not increase daily ruminating and chewing time; ruminating time per unit of NDF intake was reduced by hay supplementation (75.3 vs. 69.4 min/kg).
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada.
authors.forename: K A
authors.initials: KA
authors.lastname: Beauchemin
authors.forename: J G
authors.initials: JG
authors.lastname: Buchanan-Smith
mesh_terms: D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000502:physiology*; D004043:Dietary Fiber; D005223:Fats / Q000032:analysis; D005260:Female; D007774:Lactation; D016014:Linear Models; D008409:Mastication; D000455:Medicago sativa; D008892:Milk / Q000032:analysis; D011247:Pregnancy; D011897:Random Allocation; D012820:Silage; D014159:Transducers / Q000662:veterinary
chemical_list: D004043:Dietary Fiber; D005223:Fats