Barley (Hordeum vulgare, L.) harvested at boot (5/7/88) and
soft dough (6/6/88) stages of maturity was ensiled for
nutritive comparisons. Boot stage was wilted and soft dough
was direct cut at 15 (SD-Lo) and 25 cm (SD-Hi) above ground.
Yields (kg DM/ha) were 3690, 8750 and 6287 for boot, SD—Lo
and SD-Hi respectively. Digestibilities (%) of DM, CP and
ADF were 74.7, 74.5 and 70.8 for boot; 61.9, 50.4 and 44.7
for SD—Lo; and 62.3, 47.2 and 49.7 for SD—Hi, respectively.
Calculated TDN was 71.2, 62.0 and 62.8 for boot, SD—Lo and
SD-Hi, respectively. Thirty—six lactating Holstein cows were
fed boot silage at 75 and 60% of diet DM, SD—Lo fed at 75
and 60 and SD-Hi fed at 75 and 60, respectively. Milk yields
(kg/d) were greatest for high concentrate diets and averaged
25.7, 28.3, 24.8, 26.3, 25.7 and 26.9, respectively. There
were no differences among diets for DM intake or 4% FCM.
Boot silage had a greater In Situ rumen degradability of DM,
CP, ADF and NDF (68.6, 89.3, 44.2 and 45.1% respectively)
than SD-Lo (57.8, 76.9, 20.9 and 24.2%) and SD—Hi (62.5,
80.0, 22.8 and 26.4%). Predictability of ruminal degradability
of complete diets from weighted averages of single
ingredients determined separately was low. In Situ incubation of single ingredients resulted in underestimation of DM
and overestimation of CP degradability compared with complete