Degradabilidade in situ do amido de diferentes genótipos de milho e em diferentes tamanhos de partículas

Three corn genotypes (hard, semi-hard and semindented) ground in a 10 mm diameter sieve and separated into four particle sizes (greater than 1400 µm; between 1400 and 850 µm; between 850 and 420 µm; and smaller than 420 µm) were evaluated. Starch degradation was verified after incubations in the rumen of cattle, at times of 3, 6, 9, 15, 24 and 48 hours. Corn genotypes with lower vitreousness showed higher solubility, rumen passage rate and rumen degradation. Genotypes in smaller particles showed higher degradations than larger particles. Corn with low vitreousness associated with finer grinding showed better ruminal starch fermentation.