Technical note: concentrations of soluble, insoluble, and total dietary fiber in feed ingredients determined using Method AOAC 991.43 are not different from values determined using Method AOAC 2011.43 with the AnkomTDF Dietary Fiber Analyzer.

The primary objective of this experiment was to test the hypothesis that concentrations of soluble (SDF), insoluble (IDF), and total dietary fiber (TDF) in feed ingredients used in diets for pigs and poultry analyzed using Method AOAC 2011.25 are greater than values determined using Method AOAC 991.43. A second objective was to determine the variation that may exist among 3 laboratories using the 2 methods with the AnkomTDF Dietary Fiber Analyzer (Ankom Technology, Macedon, NY). The 3 laboratories were the Ministry of Agriculture Feed Industry Center (MAFIC) at China Agricultural University, Trouw Nutrition, and Hans H. Stein Monogastric Nutrition Laboratory at University of Illinois at Urbana-Champaign (UIUC). All laboratories analyzed SDF and IDF in feed ingredients in duplicate or triplicate using both methods AOAC 991.43 and 2011.25 with the AnkomTDF Dietary Fiber Analyzer. The 9 test ingredients were wheat, soybean meal, rapeseed meal, sugar beet pulp, peas, horse beans, native pea starch, and 2 samples of corn; 1 from Europe and 1 from China. All ingredient samples, with the exception of Chinese corn, were procured by Trouw Nutrition, ground to pass through a 0.5 mm screen, subsampled, and sent to MAFIC and UIUC. Data were analyzed using SDF, IDF, and TDF as response variables, replication as random effect, and method and location as fixed effects over all ingredients and within each ingredient. When averaged among 9 different ingredients, results indicated that SDF, IDF, and TDF values were not different with either method or at any laboratory. However, the concentration of IDF in corn, wheat, peas, and sugar beet pulp determined using Method AOAC 991.43 was greater (P < 0.05) compared with 2011.25. Soluble dietary fiber determined using Method AOAC 2011.25 was greater (P < 0.05) in corn, rapeseed meal, soybean meal, and sugar beet pulp compared with 991.43. There was no difference in TDF determined with either method, except for wheat having greater (P < 0.05) TDF when determined using Method AOAC 991.43. Interlaboratory variation for SDF, IDF, and TDF was 0.38, 0.87, 1.20, respectively, with Method AOAC 991.43 and 0.40, 0.93, and 1.27, respectively, with 2011.25. Therefore, values determined with the AnkomTDF Analyzer are repeatable among laboratories and can be used in feed formulation worldwide. In conclusion, it is recommended that Method AOAC 991.43 be used to determine SDF, IDF, and TDF in feed ingredients and diets for pigs and poultry.