Lj. Fisher et al., NUTRITIONAL-EVALUATION OF ENSILAGE MADE FROM INTERCROPPED CORN AND SUNFLOWERS, Canadian journal of animal science, 73(3), 1993, pp. 539-545
The feeding value of sunflower-corn silage relative to that of corn si
lage as the only forage fed lactating cows was established using 12 la
ctating Holstein cows in an experiment with a 2 x 2 Latin square desig
n. Treatment periods were 5 wk and there was no changeover period betw
een treatments. A constant grain intake to milk yield ratio of 1:4 was
maintained. The comparison was based on dry matter (DM) intake. milk
yield and composition, body-weight change, rumen pH and molar proporti
ons of volatile fatty acids and plasma metabolites. The sunflower-corn
silage was lower in DM content (25.4 vs. 29.2%). but higher in protei
n (11.5 vs. 8.0%), acid detergent fiber (33.2 vs. 29.2 %). fat (8.1 vs
. 2.1%) and total ash (10.6 vs. 4.9%). Silage DM intake was the same f
or both silages, but milk yield was significantly greater (P < 0.05) (
32.7 vs. 31.2 kg d-1) for cows fed sunflower-corn silage. However, bot
h milk fat (3.19 vs. 3.87%) and milk protein (3.04 vs. 3.26%) were low
er (P < 0.05) for cows fed sunflower-corn silage, resulting in a highe
r (P < 0.05) fat-corrected milk yield (30.5 vs. 28.4 kg d-1) for the c
ows fed corn silage. Type of silage fed did not alter rumen pH, but th
e molar percentage of acetic acid was higher (P < 0.05) and the molar
percentages of isovaleric and valeric acids were lower when sunflower-
corn silage was fed. The feeding of sunflower-corn silage resulted in
a significant increase (P < 0.05) in plasma urea nitrogen (10. 60 vs.
7.53 mg 100(-1)), cholesterol (7.36 vs. 5.63 mmol L-1) and triglycerid
e (0.20 vs. 0. 18 mmol L-1). Plasma levels of methionine (29.9 vs. 18.
5 mmol mL-1) and valine (208.0 vs. 19 1.0 N mol mL-1) were greater for
cows fed the sunflower-Corn silage. It was concluded from this study
that intercropped sunflower-corn harvested and preserved as silage is
an acceptable source of forage for lactating cows, but when fed as the
only source of forage it may have a negative impact on milk compositi
on.