Inter-Laboratory Comparison Of Protein Assays in The Southeast Asian Feed Industry

摘要

A series of investigations were conducted to evaluate the precision and accuracy of crude protein assays at 72 commercial feed companies. Results indicated a significant opportunity to improve accuracy and precision of analyses in many laboratories. Also, it was found that the Kjeldahl procedure detects 14.3 g/kg less protein on average than does the Dumas (combustion) procedure. This difference was most pronounced in higher protein samples. The use of- nicotinic acid and L-tryptophan reference standards were examined in 12 of the laboratories. Results suggest that digestion of samples during the Kjeldahl procedure is incomplete a majority of laboratories. The value of laboratory errors in protein analysis was estimated to be significant. With respect to feed formulation alone, losses as high as $280,000 were estimated assuming 20,000 mt per month of feed produced and an error in protein analysis of soybean meal of 14.1 g/kg.