Abstract
Normal (non-mutant) and three brown midrib (mutant) genotypes of maize (Zea mays L.) in Tr background, bm1/bm1 (bm1), bm3/bm3 (bm3), and bm1/bm1:bm3/bm3 (bm1:bm3), were harvested at 10, 35 and 55 days post-silk. Plants were separated into leaf, sheath, stem, husk, kernel, cob and tassel tissue. In vitro dry matter disappearance (IVDMD) was determined on all parts and a whole composite using the two-stage in vitro rumen fermentation technique. IVDMD of the whole plant normal, bm1, bm3, and bm1:bm3 was 68.3, 72.0, 75.5 and 77.8%, respectively, for plants harvested 35 days post-silk. IVDMD values for leaf, sheath, cob, and tassel from the same harvest were higher (P<.05) for all mutants compared to the normal counterpart. The IVDMD of bm3 and bm1:bm3 stem tissue from this harvest was higher (P<.01) than the stem tissue of bm1 or the normal counterpart. The IVDMD of the bm3 and bm1:bm3 whole plants was greater than the normal counterparts in all harvests. The higher IVDMD values of the brown midrib mutant genotypes compared to the normal were reflected in the reduced acid detergent lignin countents of the mutants. Regression and correlation analyses indicated that the altered lignin content of the mutants is the most important variable responsible for the alterations in IVDMD. Copyright © 1971. American Society of Animal Science . Copyright 1971 by American Society of Animal Science.