ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

WEENDES SYSTEM OF ANALYSIS - GENERAL FEATURES

• The proximate analysis is a scheme for routine description of animal feedstuffs devised in 1865 by Henneberg and Stohmann of the Weende Experiment Station in Germany. It is often referred to as the Weende System and was principally devised to separate carbohydrates into two fractions: crude fibre and nitrogen free extract (NFE).
• The system consists of determinations of water, ash, crude fat (ether extract), crude protein and crude fibre. NFE is also a component of the system, but it is not analysed but measured by difference.
• The proximate analysis system is both comparative and predictive in nature. Proximate analysis allows us to make legitimate comparisons of feeds on the basis of specific nutrients. This makes it possible to know how much better one feed is than another in terms of specific nutrients. We can use proximate principles to predict factors related to animal performance, like digestibility and intake and then use these values to estimate performance of animals.
• The proximate system has some failings, which prevent it from being an extremely valuable predictive aid, and considerable research has been conducted in recent years to refine it.
• To conclude, the proximate analysis system is a rather old scheme of laboratory analyses. It allows one to compare feeds on the basis of specific nutrients and to some extent to predict the components of animal performance.

• Nitrogen Free extract (NFE) is not determined actually. It is calculated  as follows:

NFE = 100 - (% Water + % Crude protein + Ether Extract + % Crude Fibre + % Ash)

• NFE represents the soluble fraction of carbohydrate consisting of sugars, starch, glycogen and to some extent hemicelluloses.

Study Questions

• List out the proximate principles.
• Name the Scientists who developed the Weende’s system of analysis?