Estimation of spring forage quality for alfalfa in New York State

Abstract

Equations were developed to estimate alfalfa neutral detergent fiber (NDF) concentration in spring growth in New York State, using easily available variables and a typical cutting height used by growers. Models with two or three explanatory variables had greater predictive accuracy than models containing more variables. Models combining alfalfa height, growing degree days, and Julian date offer the greatest potential to increase predictive accuracy. Stage of maturity did not improve prediction accuracy. Predictions using the predictive equations for alfalfa quality (PEAQ) with alfalfa sampled in New York were biased, possibly due to differences in cutting height between observations used to fit the equation, and typical cutting heights in New York State. An equation previously fit to New York, using only the explanatory variable alfalfa height, was less biased.