Influence of the Biochemical and Physical Characteristics of the Maize Grain on Ruminal Starch Degradation

This study was aimed at determining the influence of biochemical and physical features of the maize grain on ruminal starch degradation using genotypes differing in the texture of the endosperm (dent or flint) and in the starch composition (waxy [ wx ], normal [ + ], amylose extender [ ae ]). Ruminal starch degradation was (1) highest for dent types, (2) highest for ( ae ) strains irrespective the texture, and (3) dependent on the texture for ( wx ) strains. Ruminal starch degradation was independent of the amylose:amylopectin ratio in starch. The slowly degradable starch fraction which reflects the potentially degradable starch fraction that would be degraded by microorganisms given sufficient residence time in the rumen was negatively linked to the true glutelins including in the protein matrix. Ruminal starch degradability was also related to the proportion of coarse particles (1000 > d > 400 μm), which is an estimator of grain hardness.