Assessment of cell-wall digestibility in the stalks of inbred lines of maize.

摘要

Twenty-two inbred lines of maize, including 18 normal lines and 4 brown-midrib3 lines, were studied in Lusignan (France) during a 2-year period. The stalks were harvested at the silage stage, and 4 methods of cell wall digestibility assessment in the laboratory, were compared. These include direct methods (incubation of the cell wall residue with digestion enzymes (dP.NDF); incubation of the non-soluble fraction with digestion enzymes (dP.NS)) and indirect methods (calculation of the ratio betweencell wall content of the sample and cell wall content of the enzymic digestion residue of the stalk sample (dP.mes); calculation using sample cell wall content and sample digestibility, assuming a non cell wall digestibility of 100% (dP.calc)). All fourwere highly correlated and had similar ranges of variation. The methods of cell wall digestibility assessment were all significantly negatively correlated to the cell wall content, which was therefore not biased by the particular method chosen. The factthat NDF content affected NDF digestibility may reflect the influence of wall ageing on fibre degradability. Although the samples of the different genotypes were harvested at the same stage of dry matter content, the maturation stage of the walls was nevertheless not necessarily the same. The dP.NDF method was found to be the most accurate and discriminating, but not the most rapid or simplest. A good compromise between accuracy and rapidity, for routine evaluation, could be the dP.calc method.