Just Accepted
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A new analytical procedure to replace the outdated Weende proximal feed ingredient analysis paradigm is long overdue.
Abstract
Context. Proximate analysis is also called the Weende Method. It has been the standard used for describing the chemical composition of feed ingredients for the past 150+ years. Understanding of the chemical composition of feeds has changed greatly in the past 150+ years. Most of the current terms used for proximate analyses are unclear and misleading: • Crude protein, nitrogen times 6.25 describes true protein plus any other nitrogen-containing compounds including nucleotides and even phospholipids. • Crude fibre represents about half of the true fiber in most ingredients, but only about one-seventh of the fiber in important ingredients like soybean meal. • Ether Extract represents the neutral lipids in ingredients but little of the polar lipids like the lecithins. • The Nitrogen-free Extract (NFE) is not an extract at all. NFE is supposed to represent starch in feed, but it contains large proportions of pectin, hemicellulose and even some cellulose. It reflects the error in Crude Fibre. • Since NFE is a residual. It is the difference between 1000g/kg and the sum of the other components. As a result, proximate analyses always sum to a perfect 1000g/kg, enabling linear programming in feed formulation. This is a fallacy that needs to be corrected. Inadequacies of the Weende System have been known for a very long time. Animal producers desire to embrace modern technology and adapt more precise feeding techniques. Aims. To explain how 19th Century chemistry relates to 21st Century understandings of feed composition and propose an updated method of feed ingredient analysis. Methods. A new method of describing feed composition based on 13 modern chemical categories was conceived and called the “Armidale Method to distinguish it from the Weende Method”. The new feed chemical category method was used to compile a preliminary database based on: moisture, sugars, oligosaccharides, starch, pectin, hemicellulose, cellulose, lignin, ash, neutral lipids, polar lipids, true protein, and non-protein nitrogenous compounds. Key Results. Composition values for 26 ingredients compiled from three sources averaged 1032.0 49.5 g/kg, comparable to the theoretical 1000 g/kg. Implications. It is time for producers, in conjunction with nutritionists and analytical chemists, to explore the best ways to represent the composition of feed ingredients for feeding value and trade. Conclusions. The Armidale Method of analyses could be the starting point for discussions of new standardized procedures for ingredient trade and feed formulation.
AN24176 Accepted 22 August 2024
© CSIRO 2024
