High amounts of soyhulls for pelleted concentrate diets.

Twelve multiparous Holstein cows were used in a balanced, two-period, changeover design to evaluate soyhulls as a replacement for corn grain in lactation diets. Soyhulls constituted 0 (corn), 50 (corn-soyhull), and 95% (soyhulls) of the concentrate mixture, which was prepared as a 4.8-mm pellet. These concentrate mixtures were mixed with alfalfa silage (50:50 DM) and fed ad libitum as complete diets. Mean DM intakes averaged 23.7 kg/d and were similar for corn, corn-soyhulls, and soyhull diets. Corresponding daily milk yields averaged 29.8, 28.9, and 27.3 kg and milk fat averaged 3.13, 3.33, and 3.49%, resulting in similar 3.5% FCM yields and feed efficiency. Dry matter digestibility was higher for the corn diet (70%) and the corn-soyhull diet (69%) compared with the soyhull diet (61%). Digestibilities (%) of NDF were 55, 63, and 58; ADF were 56, 62, and 55; and CP were 66, 64, and 59 for corn, corn-soyhull, and soyhull diets, respectively. The gastrointestinal passage rate of alfalfa and of soyhulls was similar among diets. The energy value of soyhulls appears to be equal to corn in pelleted concentrates. The fat-depressing effect of pelleting a high starch (corn) concentrate was minimized by including soyhulls.