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Poultry Science: Extension & Outreach: Soybeans

Amino acids

Soybean meal is an excellent choice as a supplemental protein and amino acid source for poultry and swine for a number of reasons, including:

  1. Soybean meal contains a high level of protein in comparison to other plant protein sources.
  2. Soybean meal has an excellent profile of essential amino acids and these amino acids are highly digestible. Soybean meal has the highest lysine digestibility of any on the commonly available protein sources. It also ranks high in methionine, cystine and threonine digestibility. In addition, the variation in digestibility is lower for soybean meal than for other oilseed meals.
  3. Soybean meal has an excellent lysine to protein ratio.
  4. Soybean meal is a palatable source of supplemental protein. It does not adversely impact the palatability of rations for poultry or any other type of livestock.
  5. Soybean meal can serve as the sole source of supplemental protein for all types of poultry and swine at any stage of growth or production. In most poultry and swine diets soybean meal provides 80% of the dietary amino acids.
  6. Generally soybean meal is a competitively priced source of protein.

The amino acid content of soybean is affected by several factors such as plant breeding, fertilization, maturity, climatic conditions, etc. There are additional factors influencing the amino acid profile, such as origin of the raw material, processing method and storage condition. To estimate total or digestible amino acids from proximate composition a number of excellent programs are available. Most of the companies that produce amino acid supplements provide excellent programs from which one can quickly adjust the amino acid composition of a feedstuff from its chemical composition. These are available in electronic versions from which one can quickly make adjustments in amino acid composition of ingredients. To obtain copies or access these programs, contact the representatives listed below. The table below also show the regression equations to estimate amino acid content as a function of crude protein in soybean meal and soybean hulls.

Regression equations for determination of amino acid content of soybean meal and soybean hulls

% Met = %CP x 0.0096 + 0.019 %Met = %CP x 0.0096 + 0
Amino Acid Mean Equation R2
Soybean meal (n = 1916)
Met 0.64 %Met = %CP x 0.0171 – 0.163 0.61
TSAA 1.35 %TSAA = %CP x 0.0321 – 0.164 0.65
Lys 2.82 % Lys = %CP x 0.0508 + 0.432 0.67
Thr 1.82 %Thr = %CP x 0.0368 + 0.090 0.77
Leu 3.54 Leu = %CP x 0.0603 + 0.699 0.77
Val 2.23 %Val = %CP x 0.0405 + 0.321 0.63
 
Soybean hulls (n = 20)
Met

0.12 0.12
0.85  
TSAA 0.31 % TSAA = %CP x 0.0201 + 0.093 0.77
Lys 0.67 %Lys = %CP x 0.0483 + 0.142 0.81
Thr 0.39 %Thr = %CP x 0.0268 + 0.093 0.83
Trp 0.13 %Trp = %CP x 0.115 + 0.002 0.79
Arg 0.52 %Arg = %CP x 0.653 – 0.198 0.94
Ile 0.40 %Ile = %CP x 0.0363 – 0.002 0.93
Leu 0.68 %Leu = %CP x 0.0680 – 0.071 0.96
Val 0.50 % Val = %CP x 0.0304 + 0.168 0.78
 

Source: Degussa – Amino Data

Example:

CP = 47.03

            % Met = %CP x 0.0171 – 0.163 / % Met = 47.03 x 0.0171 – 0.163 = 0.6412

            % Met = 0.64

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