Commercial
samples of dietary protein supplements
were collected and evaluated by the
‘Three-Step In Situ/In Vitro Procedure’.
Rumen undegradable protein (RUP) was
determined by 16 hour incubation of
the sample in a Dacron bag suspended
in the rumen. Intestininal digestibility
(ID) of the residue was estimated by
in vitro incubation in acid followed
by pancreatin enzyme. Intestinally absorbable
dietary protein (IADP) equals the amount
of protein from a specific feed that
was available for absorption in the
small intestine, or the percentage of
RUP that was post-ruminally digested.
Protein
source
Number
of
samples
RUP,
% of CP
ID,
% of
RUP
IADP,
%
of CP
Soybean meal,
solvent extract
5
25
90
22
Soybean meal,
expeller
6
47
93
44
SoyPass*
6
66
88
58
Distillers
grains, dried
5
56
81
46
Blood
meal, batch dried
12
88
63
55
Meat
and bone meal
11
59
55
33
SoyPass
(lignosulfonate treated SBM) contributed
more IADP than either solvent extract
or expeller soybean meal, due to its
high level of RUP, without significant
reduction in digestibility.
Marshall
D. Stern, A. Bach, and S. Calsimaglia,
(1997), J Anim Sci 75:2256-2276
The
Real Comparison ...