Effects of alfalfa silage chop length and supplementary long hay on chewing and milk production of dairy cows.

Twelve lactating, multiparous Holstein cows were used to evaluate the effects of silage chop length and proportion of long hay in low and adequate forage fiber diets on chewing activities and productivity of cows fed barley-based concentrates. Diets were designed with two forage:concentrate ratios (low forage fiber, 35:65; adequate forage fiber, 65:35), combined with two theoretical chop lengths of alfalfa silage (fine, 5 mm; coarse, 10 mm), and three proportions of long-stemmed alfalfa hay (0, 10, and 20% of DMI). Increasing the chop length of silage in low forage fiber diets did not affect DMI but increased FCM; in adequate forage fiber diets, it decreased DMI and FCM. Addition of hay to silage diets increased DMI, but not FCM yield. Increasing silage chop length in diets formulated below the recommended minimal amount of NDF from forage promoted rumination and increased milk production while maintaining milk fat content and DMI. Addition of a small amount of hay to low forage fiber diets was less effective than increased particle length of silage. In adequate forage fiber diets, finely chopped silage can be used effectively.