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Concentrations of Digestible, Metabolisable and Net Energy in Soybean Meal Produced in Different Areas of the US and Fed to Pigs

14 May 2014

Although the gross energy was the same for soybean meal from all the areas of the US tested, the concentrations of Digestible Energy, Metabolisable Energy and Net Energy were lower when they were sourced from the western states than from other areas, according to new research from the Hans H. Stein Monogastric Nutrition Laboratory.

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 US 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 US and fed to growing pigs.

Experimental Design

Twenty-two sources of soybean meal were procured from crushing facilities in four zones throughout the US. Four samples came from Zone 1 in the northern US – Michigan, Minnesota and South Dakota; six samples came from Zone 2 in the eastern US – Georgia, Indiana and Ohio; seven samples came from Zone 3 in the western US – 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 26.4kg were 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 4,198kcal per 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.

Table 1. Analysed nutrient composition of corn and soybean meal (as-fed basis)
 Soybean1 
Item, %Zone 1Zone 2Zone 3Zone 4AverageP-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 46.64 ab 48.44 a 46.50 b 48.06 a 47.41 0.03
AEE 1.11 ab 0.86 b 1.37 a 0.69 b 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 7.01 a 6.31 b 7.10 a 6.96 a 6.91 0.05
a-b Means within a row lacking a common letter are different (P<0.05).
1 Zone = 1: Northern US (MI, MN and SD); Zone 2 = Eastern US (GA, IN and OH); Zone 3 = Western US (IA, MO and NE);
Zone 4 = IL.

The concentration of DE was 4,343kcal per kg for soybean meal from Zone 1, 4,319kcal per kg for Zone 2, 4,136kcal per kg for Zone 3, and 4,247kcal per kg for Zone 4 (Table 2).

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 1Zone 2Zone 3Zone 4AverageP-value
ATTD of GE, % 91.76 91.63 89.36 90.82 90.89 0.09
DE, kcal/kg 4,343 a 4,319 a 4,136 b 4,247 ab 4,261 0.01
ME, kcal/kg 4,096 a 4,117 a 3,926 bc 4,038 ab 4,044 0.04
NE, kcal/kg 2,938 a 2,952 a 2,816 b 2,894 ab 2,900 0.04
a-b Means within a row lacking a common letter are different (P<0.05).
1 Zone = 1: Northern US (MI, MN and SD); Zone 2 = Eastern US (GA, IN and OH); Zone 3 = Western US (IA, MO and NE);
Zone 4 = IL.

ME values were 4,096, 4,117, 3,926 and 4,038kcal per kg for soybean meal from Zones 1, 2, 3 and 4 respectively, and NE values were 2,938, 2,952, 2,816 and 2,894kcal per 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 fibre (NDF).

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

  • DE = 21.88 × CP - 78.53 × ash + 93.27 × AEE - 34.89 × NDF + 1.35 × ADF - 11.31 × lignin + 2749.99
  • ME = 32.55 × CP - 21.59 × ash + 71.85 × AEE - 43.07 × NDF - 4.78 × ADF + 12.87 × lignin + 2148.13

The predictive power of 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.

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

May 2014

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