Variations in Methods for Quantification of Crude Ash in Animal Feeds

Abstract

Background Crude ash is categorized as an empirical method playing an important role in the nutritional interpretation of animal feeds, allowing indirect estimation of total organic matter. Objective Our objective was to evaluate variations in laboratory procedures for crude ash quantification regarding physical parameters (i.e., time, temperature) and ashing aids and their influences on crude ash, repeatability, and discrimination power among feeds. Method The “control” method was based on a simple ignition time of 3 h at 550 °C. The variations are briefly described: increasing ashing time to 6 h; increasing temperature to 600 °C; and using two 3-h ignition cycles at 550 °C with ashing aids inclusion between them: fresh air supply, fresh air supply plus distillate water, and fresh air supply plus hydrogen peroxide. A color evaluation was also performed using a colorimetric technique. Twenty four study materials from eight different feed types were evaluated. Results The crude ash results differed among the method variations, but a consistent decrease in the estimates was observed when liquid aids were applied, which also improved repeatability. Ash residues did not present a consistent color pattern among methods, but the residues were darker when the control method was applied. Conclusions The method of obtaining ash residues in animal feeds based on the binomial 550 °C × 3 h does not have enough robustness and may overestimate crude ash in some feeds. Adjustments in either ignition time or temperature might improve crude ash test results, but the best test results are obtained using liquid ashing aids between two ignition cycles. Highlights The recommended method is based on the use of 550 °C and two 3-h ignition cycles with water added to the ash residue between cycles.

Biochemical and protein nutritional potential of mulberry (Morus alba L.) leaf: partial substitution improves the nutrition of conventional protein

“…As shown in Table 1, the crude ash content of mulberry leaves of the test species ranged from 109.67 ± 0.47 g kg −1 to 169.83 ± 0.71 g kg −1 , with an average content of 138.96 ± 18.93 g kg −1 . Crude ash contains minerals or salts such as potassium, sodium, calcium and magnesium, but excess crude ash can affect the palatability of animals and reduce intake, and can even lead to animal mineral poisoning 34 . Crude ash might decrease the nutritional evaluation of animal feeds, which in turn may compromise production and culminate in economic losses as a result of an inadequate diet formulation.…”

“…Crude ash contains minerals or salts such as potassium, sodium, calcium and magnesium, but excess crude ash can affect the palatability of animals and reduce intake, and can even lead to animal mineral poisoning. 34 Crude ash might decrease the nutritional evaluation of animal feeds, which in turn may compromise production and culminate in economic losses as a result of an inadequate diet formulation. Therefore, the animal feed should try to remove the crude ash in mulberry leaves to improve the quality of feed.…”