Effect of harvest date on shearing force of maize stems

Shearing force, one of physical characteristics, is an important indictor of forage value. Maize stem abounds in agro-pastoral ecotone in north-east China and can be utilized as ruminant forage in cold season. The objective of this study is to investigate temporal dynamics and vertical change of shearing force of maize stem because stem is the dominant morphological component contributing to stover nutritive value. Three maize varieties were selected in the study. The stem was cut into 4 segments, and every segment was measured at the approximate midpoint. The results show that shearing force increases with advancing maturity of maize. On same sampling date, shearing force of bottom part of stem is higher than that of upper part. Maize should be harvested as early as possible to avoid the decrease of forage value of stover. Of course, grain yield cannot be sacrificed greatly because maize is grown for its grain in this area. The upper part of stover should be selected as ruminant forage in order to improve the forage digestibility. If maize stover is utilized efficiently, it can play an important role for filling forage shortage gap in agro-pastoral ecotone in north-east China. There is positive relationship between shearing force and cellulose content, and between shearing force and lignin content. Measuring shearing force is very simple, so it can be used to predict forage value of maize stover.