Download RUMEN PROTECTED SOY PRODUCTS FOR DAIRY COWS

RUMEN PROTECTED SOY PRODUCTS
FOR DAIRY COWS
Ignacio R. Ipharraguerre, Jimmy H. Clark, and David E. Freeman
TAKE HOME MESSAGES
•
Passage of feed protein to the small intestine of lactating dairy cows fed protected soy
protein supplemented diets that contain 18% crude protein may be increased compared
with solvent-extracted soybean meal (SSBM) supplemented diets without significantly
affecting the supply of microbial protein.
•
Significant improvements in the supply of methionine and lysine, especially methionine,
should not be expected when SSBM is partially replaced with protected soy proteins in
the diet.
INTRODUCTION
Under conventional feeding conditions, an inadequate amount or pattern of essential amino acids
(EAA) absorbed from the small intestine of dairy cows may be partly responsible for creating or
aggravating inefficiencies in the postabsorptive metabolism of nitrogen. Selection of the proper
source of supplemental crude protein (CP) for feeding offers an excellent oportuntity for
influencing the supply of amino acids (AA) to dairy cows. Extensive degradation of protein by
ruminal microbes can compromise their value for contributing quantitatively and (or)
qualitatively to the supply of EAA that becomes available to dairy cows. Some of the most
effective methods for decreasing the ruminal degradability of soy proteins that are approved for
commercial use involve the controlled administration of heat to soybeans [i.e., expeller,
processed soybean meal (ESBM) and whole roasted soybeans (WRSB)] or heat plus reducing
sugars to soybean meal (NSBM). The impact of heat-treated soy-protein supplements on the
ruminal outflow of nitrogen (N) and carbohydrate fractions have not been compared in the same
study with lactating dairy cows. The objectives of this study were to compare the effects of
partially replacing SSBM with ESBM, NSBM, or WRSB in the diet of lactating dairy cows on
ruminal fermentation, passage of nutrients to the small intestine, and nutrient digestibility.
MATERIALS AND METHODS
Four multiparous lactating Holstein cows fistulated in the rumen and duodenum that averaged
209 d in milk were used in a 4 x 4 Latin square design to evaluate the practical replacement of
solvent SSBM with soy-protein products of reduced ruminal degradability. On a dry matter
basis, diets contained approximately 15% alfalfa silage, 25% corn silage, 34.3 to 36.9% corn
grain, and 22.0% soy products, plus minerals and vitamins; 18.2% crude protein, 25.5% neutral
detergent fiber, and 35.3% starch. In the experimental diets, SSBM was replaced with ESBM,
NSBM, or WRSB to supply 10.2% of the dietary dry matter (Table 1).
RESULTS AND DISCUSSION
Intakes of dry matter, organic matter, acid detergent and neutral detergent fiber, and starch were
unaffected by the source of soy protein (Table 2). Likewise, true ruminal fermentation of
organic matter and apparent digestion of fiber fractions and starch in the rumen and total tract
were not significantly altered by treatments. Intake of N ranged from 567 (WRSB) to 622 g/d
(ESBM), but differences among soy protein supplements were not significant (Table 3).
Compared with SSBM, the ruminal outflow of nonammonia N was higher for NSBM, tended to
be higher for ESBM, and was similar for WRSB. The intestinal supply of nonammonia
nonmicrobial N was higher for NSBM and WRSB and tended to be higher for ESBM than for
SSBM. However, no differences were detected among treatments when the flow to the
duodenum of nonammonia nonmicrobial N was expressed as a percentage of N intake or
nonammonia N flow. The ruminal outflow of microbial N, methionine, lysine, isoleucine, and
valine were not significantly altered by the source of soy protein. Differences in ruminal outflow
of arginine, histidine, leucine, phenylalanine, threonine, total essential AA, and total AA
depended upon the source of soy supplements fed to the cows (Table 3). Nitrogen digested
postruminally and in the total tract were not affected by source of soy protein. These findings
suggest that partially replacing SSBM with ESBM, NSBM, or WRSB may increase the quantity
of feed protein that reaches the small intestines of dairy cows. However, significant
improvements in the supply of previously reported limiting amino acids (methionine and lysine)
for milk production, particularly of methionine, should not be expected.
Table 1. Protein ingredient and composition of the experimental diets (DM basis).
Item
Protein
Soybean meal
Solvent-extracted (49% CP), %
Expeller2, %
Heat-xylose-treated3, %
Whole roasted soybeans4, %
Chemical
DM, %
CP, %
NDF, %
ADF, %
Starch, %
Ether extract5, %
NEL, Mcal/kg of DM5
SSBM
Treatments1
ESBM
NSBM
WRSB
19.42
…
…
…
10.10
10.20
…
…
9.20
…
10.20
…
11.80
…
…
10.20
66.5
18.2
24.2
13.3
35.3
2.9
1.67
66.8
18.1
25.4
13.3
34.8
3.6
1.67
66.7
18.2
27.1
13.3
35.8
3.0
1.66
66.8
18.3
26.5
13.8
33.7
4.6
1.73
ESBM = Expeller soybean meal, NSBM = heat-xylose treated soybean meal, SSBM = solventextracted soybean meal, WRSB = whole roasted soybeans. 2SoyPLUS® (West Central Cooperative,
Ralston, IA). 3Soy Pass® (Ligno Tech USA, Inc., Rothschild, WI). 4Vita Plus Corp., Madison, WI
(Protein dispersibility index = 8.96). 5Calculated using NRC model (2001), chemical composition of
ingredients, and least squares means for intakes for each treatment as presented in Table 2.
1
Table 2. Intake and digestibility of energy components of the diet.
Treatments1
Item
SSBM
ESBM
NSBM
WRSB
--------------- (lbs/day) --------------Dry matter intake
43.6
47.1
46.0
42.7
Apparently digested total tract
30.8
33.7
33.3
30.6
Organic matter intake
40.3
43.4
42.3
39.6
Truly digested in rumen
22.2
22.2
21.6
21.1
Apparently digested postruminally
16.5
18.7
15.9
16.1
Apparently digested total tract
29.1
31.7
31.1
28.9
Acid detergent fiber intake
5.7
6.4
5.7
5.7
Apparently digested in rumen
2.9
3.3
2.9
2.6
Apparently digested total tract
1.8
2.2
2.0
2.0
Neutral detergent fiber intake
10.6
11.9
11.5
10.8
Apparently digested in rumen
5.3
6.2
5.5
5.7
Apparently digested total tract
4.2
5.3
5.3
5.1
Starch intake
15.4
17.0
16.3
14.1
Apparently digested in rumen
8.8
10.4
9.3
8.8
Apparently digested postruminally
6.2
5.7
6.2
4.8
Apparently digested total tract
14.8
16.3
15.6
13.7
1
ESBM = Expeller soybean meal, NSBM = heat-xylose treated soybean meal, SSBM =
solvent-extracted soybean meal, WRSB = whole roasted soybeans.
Table 3. Nitrogen (N) intake and digestibility and amino acid passage to the small
intestine.
Item
SSBM
Treatments1
ESBM
NSBM
WRSB
N intake, g/d
579
622
613
567
Passage to duodenum
Total N, g/d
502
543
590
529
b
ab
a
514
564
498b
Nonammonia N, g/d
467
b
ab
a
Nonammonia nonmicrobial N, g/d
222
283
323
289a
% of NAN
48.4
56.0
58.5
57.9
% of N intake
40.0
47.4
56.0
51.0
Microbial N, g/d
245
227
236
209
N digested postruminally, g/d
344
372
409
354
N apparently digested total tract, g/d
421
450
440
393
%
72.3
72.8
71.9
69.0
Passage to small intestine, g/d
124b
155a
141a
Arginine
121b
c
bc
a
Histidine
55
57
69
61ab
Isoleucine
139
135
167
151
Leucine
229c
240bc
280a
245b
Lysine
166
164
197
186
Methionine
58
59
64
61
c
bc
a
Phenylalanine
127
132
159
141ab
Threonine
112b
118b
133a
121b
Valine
155
151
185
171
Total essential amino acids
1163b
1179b
1409a
1279ab
1
ESBM = Expeller soybean meal, NSBM = heat-xylose treated soybean meal, SSBM =
solvent-extracted soybean meal, WRSB = whole roasted soybeans.
a,b,c
Values within the same row with uncommon superscripts are different (P<0.05).