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THE origin of the Weende system of feed analysis is older than we know. Einhoff as early as 1809 prepared fiber by extraction with alcohol, dilute acid and alkali (Thaer, 1809; Henneberg and Stohmann, 1860). The early chemists thought that fiber thus obtained represented the indigestible part of the feed and estimated nutritive value on this basis. The discovery of the digestibility of fiber and cellulose in herbivores by Haubner (Henneberg and Stohmann, 1860) shattered the theoretical model upon which the proximate system of analysis was based. Further studies by Henneberg and Stohmann (1864) showed, among other things, that in some cases the crude fiber was more digestible than the nitrogen-free extract (NFE), and that the indigestible portion of the NFE was a noncarbohydrate constituent called lignin. In the face of the evidence, it is amazing that Henneberg retained the crude-fiber determination. Perhaps he had some intuition that the fiber content of feeds was related to animal performance apart from the extent of digestibility.
P.J. Van Soest (Sat,) studied this question.