EFFECT OF WHOLE CROP CEREAL GRAIN SILAGE SUBSTITUTED FOR ALFALFA SILAGE ON PERFORMANCE OF LACTATING DAIRY-COWS

Barley, oats, and triticale were planted at the University of Alberta Research Station May 22 to June 1, 1990, harvested August 5 to August 19, 1990, at the early to mid-dough stage, and ensiled. Second-cutting alfalfa was harvested at midbloom and ensiled. Twenty Holstein cows i n early lactation and 24 in midlactation were subjected to a 21-d stan dardization period (covariate) and were fed a TMR (50:50, forage: conc entrate). Forage was a combination of equal portions of silage of alfa lfa, barley, oats, and triticale. Following the covariate period, cows were offered TMR for ad libitum intake for 12 wk in which the forage portion of the TMR was one of the four silages. Diets based on oat and triticale silages lowered DMI, but overall milk production was not si gnificantly different across treatments. Digestibilities of DM, OM, CP , and ADF were highest for the alfalfa silage diet, intermediate for t he barley silage diet, and lowest for diets based on oat and triticale silages. The high dietary NDF concentration in oat and triticale sila ge limited feed intake. However, forage source had no major effect on major cow performance when forage was fed for ad libitum intake; there fore, barley, oat, and triticale silages harvested at an early stage o f maturity can be used effectively in dairy cow rations.