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Predicting Lysine, Methionine, Methionine/Cysteine and Threonine from Crude Protein. A recent paper in Feedstuffs discussed near-infrared spectrophotometry (NIRS) analyses of amino acids in soybean meal. The authors provided charts showing the variation in crude protein, lysine and methionine samples in 48% soybean meal obtained from commercial sources. They also provided regression equations for predicting lysine, methionine, methionine/cysteine and threonine from crude protein. These equations provide correlation coefficients values of 0.61-0.77 that indicate high correlations with analytical values. The regression equations cited were: |
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| % Methionine = percent crude protein
x 0.0171 - 0.163 r = 0.61 % Methionine plus cysteine = percent crude protein x 0.0321 - 0.164 r = 0.65 % Lysine = percent crude protein x 0.0508 + 0.432 r = 0.67 % Threonine = percent crude x 0.0368 + 0.090 r = 0.77 |
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| The authors point out that the
predicted values are in the middle of the range for analytical values
with values occurring higher and lower than the predicted value. They
made a strong argument for using their NIRS calibrations to rapidly and
accurately analyze the amino acid content of soybean meal and other feedstuffs.
They indicated that accurate analytical values for amino acids for each
ingredient shipment offers the nutritionist an opportunity for possible
saving in feed ingredient costs by more precisely meeting the nutritional
targets. Jonathan Goodson, J. Fontaine and B. Schirmer. 2006. NIRS analysis leads to formulation savings. Feedstuffs, July 24, p16-17. |
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