EFFECTS OF FIBER SOURCE AND METHOD OF FEEDING ON CHEWING ACTIVITIES, DIGESTIVE FUNCTION, AND PRODUCTIVITY OF DAIRY-COWS

This experiment was conducted to evaluate the effects of supplementing a silage-based diet with hay on chewing, digestive function, and productivity of dairy cattle. Eight multiparous rumen-cannulated Holstein cows were fed, in a crossover design, three diets containing 60% high moisture shelled corn-based concentrate and either: 1) 40% alfalfa silage (37% DM; 21% CP; 44% NDF); 2) 25% alfalfa silage and 15% long alfalfa grass hay (16% CP; 57% NDF) with hay offered 1 h before concentrates; or 3) 25% alfalfa silage blended and offered with 15% chopped alfalfa grass hay. Milk production (kg/d) was increased from 17.3 for diet 1 to 18.9 and 18.3 for diets 2 and 3, respectively. No change in milk fat composition resulted (mean, 3.62%). Rumination occurred in proportion to NDF intake (mean, 69.08 min/kg of NDF) regardless of diet; consequently, rumination increased from 4.6 to 5.4 h/d when diets were supplemented with hay with no effect of method of allocating hay. Rumen parameters and in sacco and total collection techniques indicated that supplemental hay mediated an improvement in fiber digestion, regardless of method of allocation of hay. © 1990, American Dairy Science Association. All rights reserved.