Evaluation of two procedures to determine acid and neutral detergent fibers in ruminant feeds of the temperate region of Argentina

The objective of this work was to compare the traditional Van Soest's procedure to analyze neutral detergent fibers (NDF) and acid detergent fibers (ADF) using filtering crucibles (VS) with a semiautomatic method which uses filter bags in an ANKOM Technology Corp. instrument (ANK). Nine ruminant feeds widely used in the temperate region of Argentina were analyzed: soybean meal expeller, alfalfa, pasture silage, ryegrass, corn silage, weeping lovegrass, tall wheatgrass, guinea grass, and barley grass. Four runs were done for each technique and feed. The comparison of ADF and NDF means by the means test for paired samples showed no significant differences between techniques (alpha = 0.01). The variability among runs was greater with the VS method than the ANK, both for NDF, standard deviation (SD) = 0.71 vs 0.39, and for ADF, SD = 0.83 vs 0.56, but the differences were not significant. The linear regressions were VS = 1.43 + 0.95 ANK; R2 = 0.99, and VS = 0.53 + 0.98 ANK; R2 = 0.99 for NDF and ADF, respectively, which indicated a strong linear relationship among the results of both procedures. It was concluded that the ANK procedure gave results comparable to those of the VS method when ruminant feeds from the temperate region of Argentina were analyzed.