Relationship Between Corn Vitreousness and Ruminal In Situ Starch Degradability

Abstract

The objective of this experiment was to determine the relationship between corn kernel vitreousness and ruminal in situ starch degradation. Fourteen U.S. and five Brazilian corn hybrids cultivated in their respective countries were evaluated. The U.S. dent hybrids were harvested at one-half milk line, black layer, and 21 d after black layer stages of maturity. Brazilian flint hybrids were harvested only at the latest stage of maturity. Vitreousness was determined by manual dissection of the kernels. Ruminal in situ degradation of starch was determined in three lactating Holstein cows fitted with ruminal cannulae. Vitreousness of the five mature Brazilian hybrids averaged 73.1% (range of 64.2% to 80.0%), while vitreousness of the 14 mature U.S. hybrids averaged 48.2% (range of 34.9% to 62.3%). Within the 14 U.S. hybrids, average vitreousness increased from 42.8% to 48.2% as stage of maturity progressed from one-half milk line to 21 d after black layer. The correlation between kernel density and vitreousness was 0.87. The correlations between kernel vitreousness or density and ruminal starch availability were -0.93 and -0.87, respectively. With advancing maturity, kernel vitreousness and density increased while ruminal starch availability decreased. Kernel vitreousness and density may be useful parameters for which to select corn hybrids for high ruminal starch availability. Density may be a more practical measurement than vitreousness for screening large corn data sets.

Effect of the ensiling time of hydrated ground corn on silage composition and in situ starch degradability

“…Correa et al (2002) reported an endosperm vitreosity averaging 73% (64.2 to 80%) for the corn harvested in Brazil.…”

“…Grain at higher concentrations of vitreous endosperm has lower ruminal in situ degradability, as well as lower in vitro and in vivo digestibility (CORREA et al, 2002;ALLEN et al, 2008). The ruminal degradability and intestinal digestibility of starch in dairy cows was higher for corn grain derived from cultivars with chalky endosperm (3% of the vitreous starch) in relation to cultivars with larger endosperm vitreousness (67% of vitreous starch) (TAYLOR;ALLEN, 2005).…”

“…However, the starch digestibility of corn grain used for dairy cow feeding ranges from 70 to 100% (FIRKINS et al, 2001). Among the main factors affecting corn starch digestibility is the storage method, grain processing methods, particle size and type of endosperm (PHILIPPEAU et al, 2000;CORREA et al, 2002;NGONYAMO-MAJEE et al, 2008).…”

Processamento do milho para vacas leiteiras em pastejo

“…Nas principais regiões produtoras de milho do mundo, o milho cultivado é quase em sua totalidade do tipo farináceo, enquanto o milho cultivado no Brasil é predominantemente do tipo duro. O milho duro apresenta reduzida degradabilidade ruminal quando comparado ao milho farináceo (Correa et al, 2002). Portanto, o processamento do milho parece ser uma Arq.…”

Degradabilidade da matéria seca e da proteína bruta de grãos secos e de silagens de grãos úmidos de híbridos de milho (Zea mays), submetidos a diferentes processamentos

“…Os grãos duros são caracterizados pela predominância de endosperma ví-treo. Do ponto de vista da nutrição animal, quanto maior a proporção de endosperma vítreo menor é a digestibilidade do amido presente neste grão (CORREA et al, 2002). Neste sentido, a caracterização física de grãos de milho poderia ser útil na caracterização do valor nutritivo (PHILLIPEAU et al,1999;GIGER-RIVERDIN, 2000).…”