Bromatological characteristics and ruminal digestibility of grain corn hybrids with different vitreousness in silage maturity

ABSTRACT. The aim of this research was to evaluate vitreousness in commercial corn hybrids with flint and dent grains and to study the effect of this characteristic on agronomic behavior, nutritional value, and ruminal degradability of grains harvested in silage maturity. Twelve commercial corn hybrids were evaluated. They were divided in two groups (six with flint grains and six with dent grains). The experiments were conducted in two municipalities represented by Guarapuava and Laranjeiras do Sul, both in Paraná State. The harvest for the grain quality analysis was performed at 3/4 of the milk line stage in the grain. The following characteristics were evaluated: grain yield, grain yield in silage maturity, vitreousness, ruminal digestibility of grain, neutral detergent fiber, acid detergent fiber and crude protein. The grains in the group of dent hybrids exhibited better degradability associated with lower vitreousness than the group of flint hybrids. The group of dent hybrids exhibited better ruminal digestibility of the grains associated with lower vitreousness versus the group of flint hybrids. There is a negative correlation between vitreousness and the digestibility of the grain; thus, vitreousness can be a criterion for selecting genotypes for forage production.摘要 本研究旨在评估携带硬粒型玉米籽粒（flint grains）与马齿型玉米籽粒（dent grains）的商业化玉米杂交种的角质率（vitreousness），并解析该性状对青贮收获期采收籽粒的农艺表现、营养价值与瘤胃降解率的影响。本研究共评估12个商业化玉米杂交种，按籽粒类型分为两组：硬粒型籽粒组与马齿型籽粒组各6个品种。试验在巴西巴拉那州的瓜拉普阿瓦市与南拉让热拉斯市两地开展。籽粒品质分析的样品采集于籽粒乳线达到3/4的生育时期。本次评估的性状包括：籽粒产量、青贮收获期籽粒产量、角质率、籽粒瘤胃消化率、中性洗涤纤维（neutral detergent fiber, NDF）、酸性洗涤纤维（acid detergent fiber, ADF）与粗蛋白（crude protein, CP）含量。相较于硬粒型杂交种组，马齿型杂交种组的籽粒角质率更低且瘤胃降解率更优。角质率与籽粒消化率呈负相关关系，因此可将角质率作为饲草生产用玉米基因型选育的参考指标。