Distillers dried grains with solubles (DDGS), a co-product of the ethanol industry, is an affordable source of energy and protein in pig diets. DDGS contains more gross energy than corn, but the energy is less digestible because of the high concentration of insoluble fiber in DDGS. If the fiber in DDGS could be made more soluble with pretreatment, its feed value would be improved.
An experiment was conducted to determine the effects of physical, chemical, and enzymatic pretreatments on the concentrations of digestible (DE) and metabolizable (ME) energy and on the apparent total tract digestibility (ATTD) of gross energy, organic matter, acid detergent fiber (ADF), and neutral (NDF) detergent fiber.
Experimental design
One batch of conventional DDGS (DDGS-CV) was divided into six sub-batches. One batch was left untreated. One was extruded (DDGS-EX). The other batches were treated with sodium hydroxide (DDGS-Na), calcium oxide (DDGS-Ca), a mixture of cellulases and xylanases (DDGS-Ce), or a mixture of xylanases and hemicellulases (DDGS-NZ).
Sixty-three growing barrows with an average initial body weight of 76.1 kg were fed one of seven diets. One diet was a basal diet containing 97% corn. The six experimental diets contained 47.95% corn and 50.0% of each of the six sub-batches of DDGS.
Results
Compared with untreated DDGS, the ATTD of gross energy and organic matter was greater (P < 0.01) in DDGS-Ce (Table 1). The ATTD of NDF was greater (P < 0.01) in DDGS-Na. The ATTD of ADF and cellulose was reduced (P < 0.01) in DDGS-EX. The ATTD of hemicellulose was greater (P < 0.01) in DDGS-EX, DDGS-Na, and DDGS-NZ, and reduced (P < 0.01) in DDGS-Ca.
On an as-fed basis, the concentrations of DE and ME in DDGS-Ce and DDGS-NZ were greater (P < 0.01) than in untreated DDGS (Table 2). DDGS-Na and DDGS-Ca contained less (P < 0.01) DE and ME than untreated DDGS.
On a dry matter basis, DE was greater (P < 0.01) in DDGS-EX, DDGS-Ce, and DDGS-NZ than in untreated DDGS. ME was greater (P < 0.01) in DDGS-Ce than in untreated DDGS. The concentrations of both DE and ME were less in (P < 0.01) DDGS-Ca than in untreated DDGS.
Key points
- Treatment with enzymes improved the DE and ME of DDGS when fed to pigs.
- There was no pretreatment that consistently increased the ATTD of gross energy, organic matter, or fiber in DDGS.
- Additional research is required to determine if other pretreatments may be used to increase the solubility of fiber in DDGS and thus increase its nutritional value.
Table 1. Apparent total tract digestibility (ATTD) of GE, OM, NDF, ADF, cellulose and hemicellulose in corn, untreated distillers dried grains with solubles (DDGS), and treated DDGS, as-fed basis
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|
Pretreated DDGS |
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|
Item |
Corn |
Untreated DDGS |
Extrusion |
Sodium hydroxide |
Calcium oxide |
Cellulase-xylanase |
Hemi- cellulase-xylanase |
P-value |
|
ATTD of GE, % |
86.60a |
71.7cd |
72.8bcd |
73.3bc |
70.4d |
75.0b |
73.9bc |
< 0.01 |
|
ATTD of OM, % |
89.74a |
71.07cd |
71.38bcd |
72.24bc |
69.49d |
73.66b |
72.75bc |
< 0.01 |
|
ATTD of NDF, % |
56.77ab |
52.46cde |
49.54de |
59.87a |
49.36e |
53.11bcd |
55.73bc |
< 0.01 |
|
ATTD of ADF, % |
57.59c |
74.35a |
68.71b |
75.53a |
74.57a |
74.42a |
73.64a |
< 0.01 |
|
ATTD of cellulose, % |
59.03c |
73.02a |
65.27bc |
77.43a |
71.05ab |
73.33a |
77.33a |
< 0.01 |
|
ATTD of hemi-cellulose, % |
56.95a |
17.68d |
28.75c |
37.97b |
9.65e |
17.57d |
25.30c |
< 0.01 |
a-eMeans within a row lacking a common superscript letter differ (P < 0.05).
Table 2.Concentration of digestible and metabolizable energy in corn, untreated distillers dried grains with solubles (DDGS), and treated DDGS, as-fed basis
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Pretreated DDGS |
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|
Item |
Corn |
Untreated DDGS |
Extrusion |
Sodium hydroxide |
Calcium oxide |
Cellulase-xylanase |
Hemi-cellulase-xylanase |
P-value |
|
DE, kcal/kg |
3,292bc |
3,279c |
3,367abc |
3,109d |
3,041d |
3,432a |
3,378ab |
< 0.01 |
|
DE, kcal/kg DM |
3,844b |
3,709c |
3,830b |
3,688c |
3,561d |
3,977a |
3,852b |
< 0.01 |
|
ME, kcal/kg |
3,201a |
3,043b |
3,078b |
2,916c |
2,833d |
3,194a |
3,108ab |
< 0.01 |
|
ME, kcal/kg DM |
3,738a |
3,442b |
3,501b |
3,458b |
3,318c |
3,701a |
3,545b |
< 0.01 |
a-dMeans within a row lacking a common superscript letter differ (P < 0.05).
This report is based on unpublished research by O. J. Rojas, S. Trupia, and H. H. Stein.