Two in vitro experiments were conducted
to determine the rates of lipolysis
and biohydrogenation of fat from raw or
processed soybeans and to examine subsequent
effects upon fiber digestibilities.
In experiment 1, substrates containing
soy oil; raw soybeans; extruded soybeans;
and soybeans roasted at 270,295,
or 325 °F were incubated with ruminal
contents for 2, 4, 6, 12, or 24 hr, and
release of free fatty acids was measured.
The fatty acids released from substrates
containing soy oil, extruded soybeans,
and raw or roasted soybeans reached
maximums at 4, 6, and 12 hr incubations,
respectively. Fatty acids in roasted
soybeans were subjected to less biohydrogenation
than those in raw or extruded
soybeans, suggesting that fatty
acids of roasted soybeans are protected
partially from ruminal bacteria. At all
incubation times, the substrates containing
soy oil or extruded soybeans had
lower and those containing roasted soybeans
had higher fiber digestibilities.
