Publication Date
1985
Location
Kyoto Japan
Description
Despite the considerable efforts expended in studying the seasonal changes in the digestibility of herbage under different harvesting regimes, there has only been slow progress in the modelling of these processes. In this paper, a quantitative description of the factors underlying seasonal changes in herbage digestibility is developed and applied to sets of data from S24 and S23 perennial ryegrass. A new variable, relative maturity, is used to describe the effect of defoliation in interrupting the process of tiller maturation which leads to the decline in digestibility. For S24, the model explained 95.5% of variation in digestibility decline, allowing accurate prediction of digestibility (RSD 1.39 digestibility units). For S23, 87 .5% of variation was explained. The models are largely independent of nitrogen and its yield effects, and allow the varietal characteristics of herbage to be compared under a constant harvesting schedule. S24 digestibility declined further and more rapidly than in S23 when compared at the same defoliation intensity, presumably due to differences in leaf:stem ratio. Relative maturity appears to be a useful concept in describing the physiological maturity of swards under different harvesting regimes.
Citation
Illius, A W., "A Simulation Model of the Seasonal Pattern of Herbage Digestibility and its Interaction with Intensity of Defoliation" (1985). IGC Proceedings (1985-2023). 18.
(URL: https://uknowledge.uky.edu/igc/1985/ses10/18)
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
A Simulation Model of the Seasonal Pattern of Herbage Digestibility and its Interaction with Intensity of Defoliation
Kyoto Japan
Despite the considerable efforts expended in studying the seasonal changes in the digestibility of herbage under different harvesting regimes, there has only been slow progress in the modelling of these processes. In this paper, a quantitative description of the factors underlying seasonal changes in herbage digestibility is developed and applied to sets of data from S24 and S23 perennial ryegrass. A new variable, relative maturity, is used to describe the effect of defoliation in interrupting the process of tiller maturation which leads to the decline in digestibility. For S24, the model explained 95.5% of variation in digestibility decline, allowing accurate prediction of digestibility (RSD 1.39 digestibility units). For S23, 87 .5% of variation was explained. The models are largely independent of nitrogen and its yield effects, and allow the varietal characteristics of herbage to be compared under a constant harvesting schedule. S24 digestibility declined further and more rapidly than in S23 when compared at the same defoliation intensity, presumably due to differences in leaf:stem ratio. Relative maturity appears to be a useful concept in describing the physiological maturity of swards under different harvesting regimes.
