Concentrations of digestible, metabolizable, and net energy in soybean meal produced in different areas of the United States and fed to pigs

One factor that affects the chemical composition of soybeans and soybean meal is where the beans were grown. For instance, soybeans grown in the northern United States contain less crude protein than soybeans grown further south. As a result, soybean meal produced from beans grown in the Northern United States often contain less crude protein than soybean meal produced from beans grown further south. However, less is known about how the concentrations of digestible (DE), metabolizable (ME), and net (NE) energy differs among meals produced from soybeans grown in different areas of the U.S. Therefore, an experiment was conducted to determine the digestibility of energy and concentrations of DE, ME, and NE in soybean meal produced from soybeans grown in different areas of the U.S. and fed to growing pigs.

Experimental design

Twenty-two sources of soybean meal were procured from crushing facilities in four zones throughout the U.S. Four samples came from Zone 1 in the northern U.S. – Michigan, Minnesota, and South Dakota. Six samples came from Zone 2 in the eastern U.S. – Georgia, Indiana, and Ohio. Seven samples came from Zone 3 in the western U.S. – Iowa, Missouri, and Nebraska, and five samples came from Illinois, which comprised Zone 4. These zones represent the locations of crushing plants and it is expected that most crushing plants sourced soybeans from the local area. Therefore, the zones are also believed to represent growing location of soybeans.

Twenty-three growing barrows with an average initial body weight of 26.4 kgwere allotted to a 23 × 8 Youden square design and fed one of 23 diets. One diet was corn-based, and the other 22 diets were based on a mixture of corn and each source of soybean meal.

Energy digestibility and concentrations of DE, ME, and NE

Soybean meal from Zones 1, 2, 3, and 4 contained 4,165, 4,209, 4,162, and 4,198 kcal/kg of gross energy, respectively (Table 1). The apparent total tract digestibility (ATTD) of gross energy did not differ among soybean meal obtained from the four different zones.

The concentration of DE was 4,343 kcal/kg for soybean meal from Zone 1, 4,319 kcal/kg for Zone 2, 4,136 kcal/kg for Zone 3, and 4,247 kcal/kg for Zone 4 (Table 2). ME values were 4,096, 4,117, 3,926, and 4,038 kcal/kg for soybean meal from Zones 1, 2, 3, and 4 respectively, and NE values were 2,938, 2,952, 2,816, and 2,894 kcal/kg. For DE, ME, and NE, soybean meal from Zone 3 contained less energy than soybean meal from Zones 1 and 2, but the same as soybean meal from Zone 4.

Correlation of chemical components and prediction equations for concentrations of DE and ME

The concentrations of DE and ME in the different sources of soybean meal was positively correlated with crude protein (CP), and negatively correlated with neutral detergent fiber (NDF).

To predict the concentrations of DE and ME in soybean meal, the optimal equation used the percentages of crude protein, ash, acid hydrolyzed ether extract (AEE), NDF, acid detergent fiber (ADF), and lignin.

DE = 21.88 x CP - 78.53 x ash + 93.27 x AEE - 34.89 x NDF + 1.35 x ADF - 11.31 lignin + 2749.99

ME = 32.55 x CP - 21.59 x ash + 71.85 x AEE - 43.07 x NDF - 4.78 x ADF + 12.87 x lignin + 2148.13

The predictive powerof these equations was relatively low, however, with an R2 value of 0.53 for the DE equation and 0.50 for the ME equation.

Key points

  • The concentrations of gross energy were the same for soybean meal from all four zones.
  • Concentrations of DE, ME, and NE were similar for soybean meal from Zones 1, 2, and 4; and decreased in soybean meal from Zone 3.
  • The concentrations of DE and ME in soybean meal can be predicted using measured values for CP, ash, AEE, NDF, ADF, and lignin. However, the R2 for the prediction equations is relatively low.

 

Table 1. Analyzed nutrient composition of corn and soybean meal (as-fed basis)

 

Soybean meal1

 

Item, %

Zone 1

Zone 2

Zone 3

Zone 4

Average

-value

GE, kcal/kg

4,165

4,209

4,162

4,198

4,184

0.08

DM

88.6

88.71

88.3

89.03

88.66

0.18

CP

46.64ab

48.44a

46.50b

48.06a

47.41

0.03

AEE

1.11ab

0.86b

1.37a

0.69b

1.01

0.04

ADF

4.81

5.2

4.89

4.76

4.91

0.34

NDF

7.78

7.53

8.21

8.94

8.11

0.13

Lignin

0.6

0.59

0.58

1.77

0.88

0.12

Ash

7.01a

6.31b

7.10a

6.96a

6.91

0.05

a-bMeans within a row lacking a common superscript are different (P < 0.05).

1Zone = 1: Northern U.S. (MI, MN, and SD); Zone 2 = Eastern U.S. (GA, IN, and OH); Zone 3 = Western U.S. (IA, MO, and NE); Zone 4 = IL.

 

Table 2. Apparent total tract digestibility of energy (ATTD) and concentration of DE, ME and NE in corn and soybean meal (DM basis)

 

Soybean meal1

 

Item

Zone 1

Zone 2

Zone 3

Zone 4

Average

P-value

ATTD of GE, %

91.76

91.63

89.36

90.82

90.89

0.09

DE, kcal/kg

4,343a

4,319a

4,136b

4,247ab

4,261

0.01

ME, kcal/kg

4,096a

4,117a

3,926bc

4,038ab

4,044

0.04

NE, kcal/kg

2,938a

2,952a

2,816b

2,894ab

2,900

0.04

a-cMeans within a row lacking a common superscript are different (P < 0.05).

1Zone = 1: Northern U.S. (MI, MN, and SD); Zone 2 = Eastern U.S. (GA, IN, and OH); Zone 3 = Western U.S. (IA, MO, and NE); Zone 4 = IL.

 

This report is based on unpublished data by Kelly M. Sotak and Hans H. Stein.

Authors: 
Publication Type: