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 p hysical features of the maize grain on ruminal starch degradation usin g 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 indepe ndent of the amylose:amylopectin ratio in starch. The slowly degradabl e starch fraction which reflects the potentially degradable starch fra ction that would be degraded by microorganisms given sufficient reside nce time in the rumen was negatively linked to the true glutelins incl uding in the protein matrix. Ruminal starch degradability was also rel ated to the proportion of coarse particles (1000 > d > 400 mu m), whic h is an estimator of grain hardness.