Addition of urea to corn silage at ensiling
time is currently an accepted practice (10).
The concurrent addition of 0.5% calcium carbonate
also has been recommended by some
researchers. However, the calcium supplied
by 0.5% limestone, when added to 33% dry
matter silage (1.5% of dry matter or 0.52%
added calcium), appears excessive when compared
with National Research Council (14)
recommended allowances for growing cattle.
If the diet is composed of a mixture of corn
silage and corn grain, calcium supplementa
tion will be more critical than with a diet
composed entirely of corn silage. Corn silage
alone is also deficient in phosphorus and supplementation
with this mineral may be desirable
under certain feeding regimens.
Increased levels of organic acids associated
with limestone and urea additions to chopped
corn plants at ensiling time (9, 11), and increased
conversion efficiency of the dry matter
of treated silage by feedlot animals (9)
have served as the bases for the recommendation
to add these compounds at ensiling time.
Essig (9) also reported that others have not
found such conclusive benefits for making
these additions. Since the effects of these
additions on fermentation have received attention
by only a limited number of researchers
(8, 13), this study was initiated to determine
the influence of added urea and limestone
or dicalcium phosphate on corn silage
fermentation.