Avaliação de híbridos de milho obtidos por cruzamento entre linhagens com diferentes degradabilidades da matéria seca

Abstract

It is not enough to have high dry matter yield to recommend corn hybrids for silage. It is also necessary that the silage presents high effective matter degradation (DEF) of the whole plant. This work had the objective of evaluating agronomic, bromatologic, and rumen degradability of commercial corn hybrids dry matter, recommended for silage production, and experimental corn hybrids from crossing among lines of high and low degradability. It was evaluated the performance of eighteen experimental corn hybrids and five commercial hybrids recommend for silage production. The experiment was established in 2003/2004 crop season in a randomized block design with three replications. The experimental plot was constituted of four rows of 5.0 meters long. Corn plants were harvested at 20 cm from soil level at milk line at half grain stage. The silages were incubated in situ for 0, 6, 12, 24 and 96 hours in the rumen of three fistulated cows and effective degradability was calculated based on 0.05%/h of passage rate. It was observed that there were corn hybrids among cultivars, that preent with high potential for good silage production high effective matter degradation (DEF) of the whole plant independently of grain texture; the strategy of synthesizing hybrids aiming high dry matter effective degradability based on lines with high DEF is correct; the low correlation between effective degradability with a agronomic, and bromatologic characteristics indicate the necessity of better use DEF to select corn hybrids aiming high quality of silage production.