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 in early lactation and 24 in midlactation were subjected to a 21-d standardization period (covariate) and were fed a TMR (50:50, forage: concentrate). Forage was a combination of equal portions of silage of alfalfa, 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 significantly different across treatments. Digestibilities of DM, OM, CP, and ADF were highest for the alfalfa silage diet, intermediate for the barley silage diet, and lowest for diets based on oat and triticale silages. The high dietary NDF concentration in oat and triticale silage limited feed intake. However, forage source had no major effect on major cow performance when forage was fed for ad libitum intake; therefore, barley, oat, and triticale silages harvested at an early stage of maturity can be used effectively in dairy cow rations.