Four rumen cannulated Holstein cows
were used in a Latin square design to
examine the effect of supplemental calcium
salt of palm oil fatty acids (.68
kg/d) or prilled fat (.68 or .91 kg/d) on
DM intake, rumen fermentation, and
nutrient digestibility. Basal diet contained
45% concentrate, 27.5% alfalfa
silage, and 27.5% corn silage (DM basis),
and treatments were balanced for calcium.
Dry matter intake was similar
among treatments. Ruminal pH, total
VFA, and molar percentage acetate and
propionate were not affected by fat
supplementation. Feeding willed fat
decreased slightly ruminal molar percentage
butyrate. Forage DM and neutral
detergent fiber disappearance from ruminally
suspended dacron bags did not
differ due to treatment. For unknown
reasons, total tract apparent digestibility
of DM and NDF was lower when cows
received the low amount but not the high
amount of prilled fat. Milk yield and fat
percentage were not significantly affected
by treatment. Milk protein was maintained
during prilled fat supplementation
but decreased .13% during calcium salt of
palm oil fatty acid supplementation. Both
fat supplements appeared inert in the
rumen and did not markedly affect
nutrient digestion when supplemented at
3.5% or less of the total ration DM.