The objective of this trial was to investigate the effects of feeding corn with different particle size (coarse vs. fine grinding) plus dried citrus pulp or soyhulls on performance of lactating dairy cows. Thirty-two mid lactating Holstein cows averaging 160 days in milk were randomly assigned to eight replicated 4 x 4 Latin squares with a 2 x 2 factorial arrangement of treatments. Animals were fed total mixed rations containing corn silage as the sole forage source. Each experimental period lasted 14 days with 10 days for diet adaptation and four days for data and sample collection. The treatments were: MFPC - finely ground corn + citrus pulp; MGPC - coarsely ground corn + citrus pulp; MGPC - finely ground corn + soyhulls; and MGCS - coarsely ground corn + soyhulls. There were no effect of diet on dry matter intake, milk yield, milk contents of fat, protein and lactose, and plasma concentrations of urea nitrogen and glucose. Significant interactions between corn particle size and byproduct source (dried citrus pulp or soyhulls) were observed for fat corrected milk, and yields of milk fat and milk total solids. It can be concluded that cow performance was not significantly affected by corn processing and byproduct source in the present study.
byproducts; energy source; grain processing; milk composition
