Yield, Chemical Composition, and Ruminai Fermentability of Corn Whole Plant, Ear, andStover as Affected by Hybrid

Abstract

Total dry matter (DM) yield and grain content are commonly considered the most important factors forevaluating corn (Zea mays L.) hybrids for silage production with no considerationgiven to the nutritive value of the nongrain portion of the plant. Because the nongrain portion mayrepresent over 50% of the total DM in corn silage, we hypothesized that hybrid differences inchemical composition and ruminai fermentability of the stover portion of the plant may account forimportant nutritional differences in corn hybrids. Six corn hybrids were planted at two locations(Nampa, ID, and Modesto, CA) and were harvested at three stages of plant maturity. Differences (P <0.01) in content of fiber components in whole plant and stover were observed amonghybrids. Ranges in hybrid means for whole plant and stover samples were: neutral detergent fiber(NDF), 41.7 to 49.0 and 50.3 to 64.1%; acid detergent fiber (ADF), 23.9 to 28.3 and 31.7 to 41.0%;cellulose, 19.2 to 22.6 and 25.5 to 33.1%; and lignin, 2.6 to 3.3 and 3.1 to 4.4%, respectively.Hybrid composition differences in total sugar and starch of stover and total sugar of whole plantalso were observed. In situ DM degradability after 24 h of ruminai incubation ranged among hybridsfrom 53.7 to 60.6% for whole-plant samples and from 44.0 to 52.3% for stover samples. Importantly,those hybrids with lower fiber content or higher in situ fermentability did not necessarily havegreater proportion of grain in the whole plant, suggesting that selection of high quality silagehybrids may be accomplished by selecting for both high stover digestibility and high grain yields.Correlation coefficients for whole-plant in situ DM degradability with neutral detergent fiber, aciddetergent fiber, cellulose, lignin, and starch were −0.85, −0.80, −0.79, −0.58, and 0.69,respectively. Results of this study indicate that differences among corn hybrids in whole-plant andstover fiber content may be important in identification of hybrids with improved silage feedingvalue.