Quantifying non-fibrous carbohydrates, acid detergent fiber and cellulose of forage through an in vitro gas production technique.

The in vitro gas production (GP) technique has been useful for evaluating the potential degradability of feedstuffs in ruminal environments; GP is related to feedstuff ingredients' components.

Linear models were generated and validated as alternatives of quantifying neutral detergent-soluble fiber (NDSF), Starch (St)/hemicellulose (Hem), and cellulose (Cel) through GP. Residuals of models obtained from peaks of GP [0-8 h (GP-8), >8-24 h (GP-24), >24-48 h (GP-48), >24-81 h (GP-81)]) of 0.02, 0.04, 0.08, 0.12, 0.20 g of glucose (Glu), St and Cel incubations were analyzed in mixtures of Glu, Starch and Cel (0.05, 0.10, 0.15 g; 27 combinations). The best fitting models (r² from 0.709 to 0.935) were tested on corn stover (CS) to quantify rapid fermentation fractions (RF; equivalent to Glu), medium fermentation fractions (MF; equivalent to St) and low fermentation fractions (LF48; equivalent to Cel); in CS, RF, MF and LF models had standardized residuals (SR)<0.09. Analysis with Leucaena (Leucaena leucocephala Lam. de Wit) and star grass (Cynodon nlemfuensis Vanderyst) consider high-protein ingredients.

The in vitro GP of RF, MF and LF48 fractions equivalent to Glu, St and Cel are affected by maturity and harvest time even when chemical composition remains similar, then RF, MF and LF48 should be considered during the design of ruminant diets. In vitro GP could be used to quantify the components of some forages, but further studies are necessary. This article is protected by copyright. All rights reserved.