Carbohydrate and Aspergillus oryzae effects on intake, digestion, and milk production by dairy cows

Six multiparous, ruminally cannulated Holstein cows (46 DIM, 584 kg of BW) and 6 primiparous Holstein cows (35 DIM, 506 kg of BW) were used in two 6 x 6 Latin squares with 21-d periods to examine the effects of level of non-fiber carbohydrate, source of fibrous carbohydrate, and Aspergillus oryzae fermentation extract on intake, digestion, and milk production. Treatments were 42 and 36% non-fiber carbohydrate; shelled corn and soybean meal were replaced partially by beet pulp and dried brewers grains or soy hulls and dried brewers grains in 36% non-fiber carbohydrate diets. These three diets then were supplemented with 0 or 3 g/d of A. oryzae. Milk production and composition and DMI were not significantly affected by level or source of carbohydrate, although intake of NDF was significantly higher for 36% non-fiber carbohydrate diets. Total tract apparent digestibilities of ADF and NDF were higher for 36% non-fiber carbohydrate diets. Supplementation with A. oryzae did not significantly affect DMI, milk production, or total tract apparent digestibilities; however, milk fat content was decreased. Partial replacement of corn with fibrous carbohydrate sources, beet pulp and soy hulls, did not adversely affect intake or milk production in early lactation cows fed alfalfa silage-based diets.