Van Soest is more reliable because CF removes some fiber in the process. This is noted in your attached document.

Dear Moah Khalid,

the crude fiber, derived by Weende method, including also lignin that is a polymer of phenyl propane and it is not a carbohydrate.

Instead, Van soest method or analyses of fiber fractions is able to estimate the lignin.

This difference is very important for the animal nutrition

best regards

Martino

Dear Khalid,

CF provides you 1 result (roughly cellulose content) while Van Soest provides you 3 results:

- NDF fraction contains hemicelluloses, cellulose, lignins and is a general measurement of "total" fibre (in fact some fibre escape during neutral detergent analysis)

- ADF fraction contains mainly cellulose and a part of lignins. In therory this is more or less equivalent to CF

- ADL is a measurement of lignins that escaped ADF then H2SO4 treatments (i.e. not all lignins), but it is useful in animal nutrition as a marker of indigestible fraction.

Now: on the importance of performing both analyses : CF is an older method and in some cases, the (old) equations of prediction of energy you can find in litterature are based on CF. It can still be useful in practice. But in scientific terms Van Soest sequence is much more informative.

Attached is a graph with the relationships between CF and the 3 van Soest fractions in a database of 10000 samples covering all kinds of materials (forages, rangeland samples including shrubs and trees, cereals and byproducts, feces from digestibility experiments etc.). You see that:

- CF and NDF are not very strongly linked (R² around 0.7 in this dataset) : the dispersion shows that they do not provide the same information when a large variety of samples is used

- CF and ADF are linked, but some groups of samples appear. Samples of a different nature can have different ADF/CF ratio (e.g. higher ratios in tree leaves). within groups the R² is quite high. You'll notice that ADF is almost always > to CF).

- CF and ADL are not linked in general (they can be within a particular species or group of species).

I see that you take advantage of Van Soest method for determining specific type of fibre i.e. NDF and ADF and by difference you can calculate hemicelluloses, but determination of CF will gave general fibre contents of feed stuffs. I think that the comment by Denis is very helpful for you to deep understanding the differences between different kind of fibre and their role in animal nutrition. 

In Van Soest analisis the anatomi of cell is considered. The NDF (neutral detergent fiber) is the cell wall and the solution is the citoplasmic content. So in the NDF celulosa, hemicelulosa and lignin are included. In Crude Fiber that is Wende analisis is only a part of total cell wall allmost celulosa content. 

Dear Sir

respecting to other comments, there is not any difference between CF and NDF in chemical aspect, because both include cellulose, hemicellulose and lignin. But in the Van Soast method you can measure  cellulose, hemicellulose and lignin separately. So nutritionally aspect the NDF in this method is correlated with fiber intake but the ADF is correlated  with the fiber digestibility, because it only contain the cellulose and lignin fraction. If you have 2 different forage crops with similar CF content , but when you measure their digestibility one forage is higher than the other ; you can not interpret the results unless you measure the NDF, ADF and ADL with the Van Soast technique. So you can find which forage have higher lignin or cellulose content. 

This is a simple answer to your question but if you eager to learn more, please read the Van Soast  et al articles. 

Dear Sir

the methods of analysis  for CF and NDF are different. Also, Van Soest is more reliable because CF removes some hemicelluloses and soluble fiber in the process.

nowadays, in ruminant nutrition, we used Van Soest method. also, in Van Soest method, we can determine hemicelluloses, ADF and ADL.

I Think Mohammad has a conceptual mistake in his first statement. CF and NDF cannot be considered as chemically equivalent. CF solubilizes partially hemicelluloses and even some lignin. This "error" is more important in fibrous feeds. This is clearly shown in the graphs uploaded by  Denis Bastianelli...By the way, thanks for that Denis. It shows the differences clearly 

Thank you so much Denis and all... this really help me in understanding the different between these two methods.

Dear Khalid, with due respect of all repondees, The think is that both of the methods analyse fiber portion of a diet and if you want to produce this data for a scientific paper, van soest analysis or NDF, ADF are more acceptable data than CF, as CF procedure has many limitations and errors..

The NDF procedure is for ruminants in monogastrics is not relevant. NDF is partialy digested un rumen. NDF is the hole cell wall. CF is proximaly celulose content in cell wall. 

Basically the same. The differences raises from the chemical used. In NDF analysis samples treated with Notr dedergent that allow full recovery of HMC, SEL and Lignin. However, because you use diluted acid and alcali in CF analysis, some losses is happening in the HMC as it can be soluble in these chemical. Therefore even both analysis meant to give you cell wall contenet of plant (HMC, CEL, Lignin), CF always gives less results. 

I recommend to you Mohd Khalid Khalil the paper I had recently published in Animal Feed Science and Technology, which is now available online (Apr 2018):

Silva R.S.T., Fernandes A.M., Gomes R.S., Bendia L.C.R., Silva L.C. & R.A.M. Vieira, 2018. On the specificity of different methods for neutral detergent fiber and related problems. Animal Feed Science and Technolgy, in press, https://doi.org/10.1016/j.anifeedsci.2018.04.003

There you will see an interesting discussion about specificity of fiber method and the most important difference from CF.

Thank you so much for all of responses, specially article that have published by Ricardo Augusto Mendonça Vieira in AFST 2018.

what is the Crude Fibre requirement for Dairy Cattle? I cannot find it anywhere since the terminology is so old and not really used now, but I need to get it thanks!

There is no crude fiber requirement for dairy cows in any contemporary feeding system that I'm aware of

Please, is decahydtophtalene reagent garde necessary in the experience?

Dear Friend

Crude fiber includes most of the cellulose and some lignin, while the neutral detergent fiber (NDF) includes, in addition to those, hemicellolose. I suggest you better value the NDF, it also estimates the consumption potential and there are many equations of energy evaluation of forajers from the neutral detergent fiber.