Corn Silage Management I: Effects of Hybrid, Maturity, and Mechanical Processing on Chemical and Physical Characteristics

Abstract

Two experiments were conducted to evaluate the ef- fects of hybrid, maturity, and mechanical processing of whole plant corn on chemical and physical characteris- tics, particle size, pack density, and dry matter recov- ery. In the first experiment, hybrid 3845 whole plant corn was harvested at hard dough, one-third milkline, and two-thirds milkline with a theoretical length-of-cut of 6.4 mm. In the second experiment, hybrids 3845 and Quanta were harvested at one-third milkline, two- thirds milkline, and blackline stages of maturity with a theoretical length-of-cut of 12.7 mm. At each stage of maturity, corn was harvested with and without me- chanical processing by using a John Deere 5830 har- vester with an onboard kernel processor. The percent- age of intact corn kernels present in unprocessed corn silage explained 62% of variation in total tract starch digestibility. As the amount of intact kernels increased, total tract starch digestibility decreased. Post-ensiled vitreousness of corn kernels within the corn silage ex- plained 31 and 48% of the variation of total tract starch digestibility for processed and unprocessed treatments, respectively. For a given amount of vitreous starch in corn kernels, total tract starch digestibility was lower for cows fed unprocessed corn silage compared with processed corn silage. This suggests that processing corn silage disrupts the dense protein matrix within the corn kernel where starch is embedded, therefore making thestarch moreavailable fordigestion. Particle size of corn silage and orts that contained corn silage was reduced when it was processed. Wet pack density was greater for processed compared with unprocessed corn silage.