Using the Correlation of Forage Digestibility and Morphological Composition to Manage a Cool-Season Grass Sward.

Increased maturity at harvest has a large impact on quality, decreasing protein concentrations and increasing fiber. Highly lignified forages remain in the rumen longer because of their slow rate of digestion, decreasing DMI and thus animal performance. Forage nutritive value is primarily affected by maturity, but also by the environment and plant morphological characteristics, such as on leaf:stem ratio. Cool-season grasses have a low leaf:stem ratio with advanced maturity. Stems are highly lignified therefore affecting the overall quality of the forage. The objective of this study was to analyze correlations between forage quality and morphological composition of a mixed cool-season grass sward throughout the growing season in Ohio and its relationships with digestible yield. This information will be useful to help producers to maintain an optimum range of digestible yield and increase the leaf:stem proportion by harvesting the forage  with lower fiber concentration. The research was conducted at Columbus, OH, from April to October 2009 and 2010. Treatments consisted of five different dates of initiation of growth (clipping dates) in a mixed cool-season grass species sward, replicated 4 times in a randomized complete block design. Samples to characterize the nutritive value of the sward canopy were randomly collected weekly from each experimental unit and the procedure was to collect samples from lower stubble to a 5-cm height and from every 10-cm vertical strata of the offered forage. Morphological composition of the sward was quantified and forage quality analyses were conducted.