Thirty six mid lactating Holstein cows, 123 days in milk (DIM), were used to evaluate the substitution of ground corn (GC) by soybean hulls (SH) for in total mixed diets containing corn silage as the main forage source and citrus pulp as part of the energy source. The replacement of 0, 10 and 20% of ground corn by soybean hulls in total mixed diets (%DM) were evaluated: SH 0 - 0% SH and 20% GC, CS 10: 10% SH and 10% GC, and CS 20 - 20% SH and 0% GC. Performance and metabolism characteristics such as dry matter intake, milk yield and composition, milk urea N concentration, and plasma glucose were evaluated. Cows were assigned 3 x 3 Latin Square experimental design, with 12 replications, according to milk yield, DIM and parity. No effects were observed by the inclusion of SH in the diets on DM intake (22.84 kg/day), milk yield (28.33 kg/day) or 3.5% fat corrected milk (28.48 kg/day). However, linearly increased total milk fat production and linearly decreased MUN concentration in milk. The replacement of ground corn per soybean hulls in the feeding of lactating cows could be good alternative since byproduct cost be competitive.
byproducts; fibrous feeds; lactating cows; milk production and composition; ruminants
