2009 Proceedings of the Cornell Nutrition Conference For Feed ...

Table 3. Reactive Lys content of intact
and rumen undegraded residue
blood meal samples determined
using the homoarginine method
(Boucher, 2008)
Intact sample
Reactive
Lys, %
Bovine BM1 96.66
Bovine BM2 93.05
Heated bovine BM 96.20
Porcine BM1 96.52
Porcine BM2 92.59
Heated porcine BM
Rumen undegraded
residue
94.37
Bovine BM1rr a
66.98
Bovine BM2rr 72.56
Heated bovine BMrr 45.30
Porcine BM1rr 71.30
Porcine BM2rr 93.12
Heated porcine BMrr 86.83
RUP-Lys dig. vs.
reactive RUP-Lys b R 2 = 0.05
Lys dig. vs. reactive Lys c R 2 = 0.29
a rr = rumen residue.
b Digestibility of lysine in rumen
undegraded protein (RUP) determined
in roosters and reactive lysine in RUP
determine via the homoarginine
method.
c Lysine digestibility determined in
roosters and reactive lysine
determined via the homoarginine
method.
Ohio State Modifications of the Three-step
Procedure
In the previously described analysis of in
vitro AA digestibility of BM samples, it is
recognized that the sample size (n = 6) is
small. In a more extensive analysis of RUP
digestibility, 265 blood meal samples were
evaluated using the 3-step in-situ/in-vitro
method described by Calsamiglia and Stern
(1995) with modifications (Table 4; St-Pierre,
unpublished observations). Considerable
inter-assay and inter-lab variation was
observed when the original Calsamiglia and
Stern (1995) procedure was applied to BM.
Therefore, the following modifications were
made at Ohio State: (1) partial
standardization of enzymes, (2) use of fuzzy
standards (i.e., standards whose analytical
values are not precisely known), correction
for wash-out, and (3) Bayesian statistics to
adjust for inter-assay variation. Using these
modifications, the inter-assay variation was
reduced five fold compared with the original
3-step procedure. Amino acid digestibilities
were corrected such that the sum of all
digestible AA was equal to the adjusted
digestible protein. While the CP and RUP
averages (Table 4) were similar to those
reported for ring-dried blood meal in the NRC
2001, the RUP digestibility of 64.6% (Table
4) was lower than the NRC (2001) library
value of 80%. Amino acid digestibilities were
similar to RUP digestibility with the exception
of lysine, which was lower (56.0 + 27.1%;
data not shown).
While heating of BM can increase its RUP, heating does not consistently alter the
digestibility of the RUP once it arrives at the small intestine. This concept is clearly
demonstrated in Figure 3, because there is no relationship between the amount of RUP
and RUP digestibility as measured in the Ohio State modified 3-step procedure.
Figure 4 clearly demonstrates that Lys digestibility of BM was almost always
lower than digestibility of RUP, and as the RUP digestibility of BM decreased RUP-Lys
digestibility of BM decreased even more. Therefore, the amount of MP-Lys supplied to
the animal when BM is fed can be substantially less than predicted by ruminant nutrition
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